MRI Liver – Generic Standard Protocol

1. Executive Summary

Liver MRI has become the primary imaging modality for hepatic lesion characterisation in adults, surpassing CT in diagnostic specificity for focal liver lesions and matching it for HCC diagnosis in patients with cirrhosis. Unlike CT, liver MRI provides simultaneous morphological, functional, diffusion, and perfusion information without ionising radiation, and the availability of hepatobiliary contrast agents adds a cell-function dimension that CT cannot replicate.

The ACR Appropriateness Criteria designate multiparametric MRI with contrast as highly appropriate for initial characterisation of indeterminate hepatic lesions [1]. The ESGAR 2016 consensus established the minimal protocol standard — T2 single-shot, T2 TSE respiratory-triggered, T1 dual-echo, DWI, T1 3D dynamic multiphase — that remains the structural basis of all current adult liver MRI protocols [2]. The AASLD 2023 guidance accepts both multiphasic CT and MRI for non-invasive HCC diagnosis, reserving MRI over CT when US-based surveillance is suboptimal [3].

The generic adult liver MRI protocol described in this page covers: focal lesion characterisation; HCC in the at-risk patient/cirrhosis context; hepatic metastases; biliary obstruction and cholangiopathy; post-locoregional therapy assessment. It does not address paediatric imaging, transplant-specific protocols, quantitative MRE/fibrosis assessment, or fully standardised abbreviated surveillance programmes.

1.1 Core Strengths

Multi-parametric tissue characterisation: no other modality combines T1 contrast kinetics, T2 tissue signal, diffusion restriction, and hepatobiliary uptake in a single examination. This combination allows lesion characterisation that is qualitatively superior to CT for most focal hepatic lesions.

Hepatobiliary contrast agents: gadoxetate and gadobenate enable a hepatobiliary phase (HBP) that directly reflects hepatocyte function. This phase identifies lesions lacking functional hepatocytes (most malignancies), aids detection of sub-centimetre metastases, and provides non-invasive biliary tree mapping — none of which is achievable with CT or conventional extracellular contrast MRI [2, 18, 21].

DWI for lesion detection: DWI significantly increases sensitivity for hepatic metastases, particularly lesions < 1 cm, and the combination of DWI with HBP is the most sensitive approach for colorectal liver metastases, including sub-centimetre disease [13].

LI-RADS compatibility: the multiparametric protocol generates all the imaging features required for LI-RADS categorisation — APHE, washout, capsule, T2 signal, diffusion, HBP uptake — enabling standardised, reproducible communication for HCC risk stratification in at-risk populations [3, 4, 5].

No ionising radiation: for serial follow-up in cirrhosis, young patients, and post-treatment surveillance, the absence of cumulative radiation dose is clinically relevant.

1.2 Intrinsic Limitations of the Generic Protocol

Motion and breath-hold dependence: the liver moves 1–4 cm during free breathing. The diagnostic quality of all non-single-shot sequences — particularly the dynamic multiphasic T1 acquisition — depends entirely on the patient's ability to perform reproducible breath-holds on command. Motion is the single largest cause of non-diagnostic liver MRI and is not fully compensable by any technical strategy.

Arterial phase timing sensitivity: the late hepatic arterial phase window (approximately 10–15 seconds) that captures APHE — the key LI-RADS feature for HCC — requires precise bolus synchronisation. An arterial phase acquired 5 seconds early or late changes the diagnostic interpretation. Gadoxetate-enhanced protocols carry an additional risk of transient severe motion (TSM), with a pooled incidence of approximately 13% in single-phase arterial protocols [11].

Hepatobiliary phase dependence on hepatic function: the HBP is diagnostically useful only when hepatocyte uptake is adequate. In advanced cirrhosis (particularly MELD ≥ 10–15), HBP uptake may be insufficient for reliable interpretation. Gadoxetate consistently outperforms gadobenate in cirrhotic patients across disease severity levels, but even gadoxetate HBP may be non-diagnostic when hepatic function is severely impaired [19].

ADC non-specificity: DWI increases lesion detection but ADC alone is insufficiently specific to distinguish malignant from benign lesions. Diffusion data must always be interpreted in the multi-parametric context [8, 9].

No universal standard for abbreviated protocols: abbreviated MRI (AMRI) for HCC surveillance shows favourable performance in meta-analyses [14, 15, 16, 17] but is not endorsed as a routine standard by the AASLD [3], and protocol heterogeneity across published series limits direct comparison.

When dedicated child protocols are required: post-surgical hepatic resection; post-interventional locoregional therapy (LR-TR algorithm); liver transplant donor/recipient assessment; MRE for fibrosis quantification; dedicated MRCP for primary sclerosing cholangitis; paediatric hepatic MRI; abbreviated surveillance MRI programme design.

2. Main Clinical Indications

2.1 Standard Indications

Indeterminate hepatic lesion characterisation is the most common indication for liver MRI referral. Lesions that are incompletely characterised on ultrasound or CT — including incidentally discovered cyst-vs-solid ambiguity, haemangioma variants, focal nodular hyperplasia (FNH) uncertainty, or indeterminate enhancing nodules — are the clinical scenario for which the generic multiparametric protocol was primarily designed. The ACR designates multiparametric MRI as the preferred characterisation modality in this context [1]. The generic protocol with a hepatobiliary agent provides the full range of features needed for characterisation in the non-cirrhotic patient.

HCC surveillance and diagnosis in at-risk patients covers patients with cirrhosis of any aetiology and patients with chronic hepatitis B without cirrhosis who meet AASLD risk criteria. When ultrasound-based surveillance produces a suboptimal study or identifies a lesion requiring further evaluation, multiphasic liver MRI is the standard diagnostic modality. The AASLD 2023 guidance accepts both multiphasic CT and MRI as non-invasive diagnostic modalities for HCC, with MRI often preferred for its superior soft tissue characterisation and absence of radiation [3]. LI-RADS 2024 criteria apply to all imaging performed in this population [4, 5].

Hepatic metastases from known or suspected primary malignancy — colorectal, neuroendocrine, breast, lung, melanoma, and others — require baseline staging and response assessment. The combination of DWI and HBP (gadoxetate or gadobenate) provides the highest sensitivity for sub-centimetre metastasis detection, outperforming CT in multiple meta-analyses for colorectal liver metastases [13]. The generic protocol is usually sufficient; modifications for specific tumour types are addressed in the dedicated metastases child protocol.

Biliary obstruction and cholangiopathy: when biliary dilatation is identified on ultrasound or CT, liver MRI with MRCP addition provides non-invasive ductal mapping — choledocholithiasis, Mirizzi syndrome, cholangiocarcinoma, primary sclerosing cholangitis, post-operative biliary complications. MRCP is a conditional addition to the standard protocol, not a universal component; it should be added whenever biliary anatomy is the primary clinical question [2, 23].

Post-locoregional therapy assessment (ablation, TACE, SIRT, external beam radiation) follows LI-RADS Treatment Response Assessment (LR-TR) criteria, updated in 2024 with separate algorithms for radiation and non-radiation therapies [4, 6]. The protocol must document the treatment type, target lesion location, and include subtraction imaging when T1 pre-treatment signal is elevated.

Complementary assessment after inconclusive ultrasound or CT: when cross-sectional imaging is inconclusive due to technical limitations (obesity-related CT artefact, iodine contrast allergy, renal insufficiency precluding CT contrast) or when CT findings require tissue characterisation beyond CT's capability.

2.2 Urgent Red Flags Requiring Expedited or Emergency Imaging

The liver is not primarily an organ of emergency MRI indications. In haemodynamically unstable polytrauma, contrast-enhanced CT remains the first-line investigation. However, the following scenarios require expedited or prioritised access:

3. Preparation Reference

Universal MRI safety screening, ferromagnetic implant assessment, and IV access documentation are described in the general MRI preparation page and are not repeated here.

3.1 Anatomy-Specific Preparation Items

Fasting: a 4–6 hour fast before liver MRI is strongly recommended. Fasting reduces gastric and small bowel fluid that degrades MRCP and reduces bowel peristalsis that generates motion artefacts on abdominal sequences. For MRCP-included protocols, 4–6 hour strict fasting is the standard.

Renal function assessment: eGFR must be documented before gadolinium-based contrast agent (GBCA) administration. For eGFR < 30 mL/min/1.73 m², the risk-benefit of GBCA must be assessed against current ESR/ESMRMB recommendations [22]. Hepatobiliary agents at standard doses can be used in most patients with eGFR > 30 mL/min/1.73 m², but local protocols should specify the threshold for contrast deferral.

Medication history relevant to MRI: iron chelation therapy may affect susceptibility sequences; amiodarone causes hepatic T1 shortening (amiodarone contains iodine and alters T1 signal); metallic biliary stents produce susceptibility artefacts on MRCP.

Prior treatment documentation: in post-therapy protocols, the exact treatment modality (thermal ablation type, TACE, TARE/SIRT, radiation therapy, surgical resection), date, and target lesion location must be documented before scanning. This information is essential for LR-TR algorithm application [4, 6] and determines whether subtraction imaging is required.

Breath-hold training: before the examination, the technologist should coach the patient in consistent expiratory breath-holds of 15–20 seconds. Inconsistent breath-hold depth — not simply inadequate duration — is the most common cause of misregistration between dynamic phases. The target is reproducible expiratory position, not maximal inspiration.

Antiperistaltic agents: hyoscine butylbromide (Buscopan, 20–40 mg IV) or glucagon (0.1 mg IV) can reduce bowel motion artefacts, particularly relevant for MRCP sequences and in patients with bowel peristalsis-related artefacts on abdominal T2 sequences. Use is centre-dependent and not universally mandated; contraindications (glaucoma, prostate hypertrophy for Buscopan; glucagonoma) must be verified.

Contrast agent selection decision: the choice between extracellular GBCA (gadoteridol, gadobutrol, gadoterate) and hepatobiliary agent (gadoxetate, gadobenate) should be made before positioning. Each has implications for protocol sequence and timing that cannot be retroactively changed once injection has occurred.

3.2 Patient Positioning on the MRI System

Standard position: supine, feet-first entry. Arms elevated above the head (if tolerated) to reduce aliasing in the FOV and improve coil coupling efficiency. If shoulder or upper extremity conditions preclude arm elevation, arms-at-sides positioning requires corresponding FOV and phase encoding adjustments.

Coil selection: multi-channel phased-array surface coil (body matrix) combined with the integrated spine coil provides the optimal SNR for liver MRI at both 1.5T and 3T. A minimum of 16-channel combined coil configuration is recommended for adequate parallel imaging performance. The use of dedicated liver surface coils is not standard practice; full-body phased-array provides sufficient SNR for all clinical liver sequences at current resolutions.

Centring: isocentre at the level of the liver dome — typically 2–5 cm above the xiphisternum. Verify on the three-plane localiser that the entire liver including the dome (segment VIII, dome of segment IV) and the inferior tip (segment VI) are within the planned FOV. For tall patients, the caudate lobe (segment I) and the most superior hepatic veins may require minor superior shift.

FOV considerations: the axial FOV must cover the full liver transverse diameter plus the hila bilaterally. A phase FOV of 75–80% with appropriate phase oversampling is acceptable to reduce scan time without aliasing.

4. Standard Protocol Design

The liver MRI protocol is built around a mandatory core acquired in a defined sequence, with conditional additions based on the specific indication. The entire examination — excluding any HBP wait time — can be completed in 30–40 minutes at 3T with modern acceleration techniques.

4.1 Mandatory Core Sequences

4.2 Conditional Sequences

4.3 Rationale Summary Per Sequence

T2 single-shot (HASTE/SSFSE) provides the motion-robust baseline T2 assessment. Its primary diagnostic value is lesion detection and initial characterisation (cystic vs. solid, T2 signal intensity pattern) in patients with limited breath-holding capacity. Haemangiomas, simple cysts, and bile ducts are all well-characterised. Its limitations — lower spatial resolution and intrinsic T2 blurring from the long echo train — make it complementary to rather than a replacement for respiratory-triggered T2 TSE. It should always be acquired early in the protocol before patient fatigue compromises respiratory compliance.

T2 TSE with respiratory triggering or navigator provides the higher-quality T2 image for detailed lesion characterisation — septa, mural nodules, internal architecture, ductal morphology, cholangiopathy signs. The distinction between single-shot T2 and triggered T2 TSE is diagnostically meaningful for lesion characterisation: triggered T2 is essential for defining lesion wall architecture, mural septa, and subtle T2 signal differences between HCC, dysplastic nodules, and benign regenerative nodules in cirrhosis. A coronal T2 TSE provides the overview view of the biliary tree, hepatic veins, and IVC that is essential for staging assessments.

T1 dual-echo in-phase/opposed-phase detects intracellular fat (hepatic steatosis, adrenal adenoma lipid content, HCC fat content) and confirms the presence of iron (loss of signal on in-phase relative to opposed-phase). The signal drop on opposed-phase images indicates fat-water co-existence in the same voxel — the basis for characterising focal fatty infiltration, hepatic adenoma subtypes, and some well-differentiated HCCs. This sequence also provides the essential pre-contrast T1 baseline for subtraction imaging when post-treatment T1-bright signal is expected.

The practical limitation is that IP/OP provides qualitative or semi-quantitative fat assessment only. It does not replace PDFF (proton density fat fraction) Dixon quantification for diagnostic-grade hepatic steatosis grading. A visible signal drop on OP images indicates fat presence but cannot reliably determine fat fraction at values below approximately 15–20%.

DWI with multi-b-value acquisition and ADC map is the most sensitive sequence for focal lesion detection, particularly sub-centimetre metastases. The combination of DWI with gadoxetate HBP achieves the highest sensitivity for colorectal liver metastases including lesions below 1 cm [13]. High b-value images (b = 800–1000 s/mm²) suppress background liver signal and increase conspicuity of restricted-diffusion lesions. The ADC map provides quantitative apparent diffusion coefficient values but cannot independently distinguish malignant from benign lesions — a critical interpretation limitation [8, 9]. DWI must always be interpreted in conjunction with morphological and enhancement sequences.

The recommended b-value scheme for hepatic DWI is: low b (0–50 s/mm²) for T2-weighted background reference + intermediate b (400–500 s/mm²) for IVIM separation + high b (800–1000 s/mm²) for restricted diffusion detection. The exact scheme is vendor- and field-strength-dependent and should be validated locally for SNR and distortion characteristics.

T1 3D fat-saturated pre-contrast is the essential baseline before dynamic injection. It serves three purposes: (1) identifying intrinsically T1-bright lesions (haemorrhage, melanin deposition, fat, protein-rich fluid) that could otherwise be misinterpreted as enhancement; (2) providing the reference image for subtraction in post-treatment protocols; (3) establishing the imaging geometry that must be identically reproduced for all subsequent dynamic phases. This sequence must be acquired immediately before contrast injection without any change in patient position or sequence parameters.

T1 3D dynamic phases (late arterial, portal venous, delayed) constitute the diagnostic cornerstone for vascular characterisation of hepatic lesions and LI-RADS feature assessment. The three phases serve distinct purposes:

The late hepatic arterial phase is the most diagnostically critical acquisition in the entire liver MRI protocol. It must be timed to capture simultaneous opacification of the hepatic artery and portal vein while the hepatic veins remain non-enhanced. This window — the "late arterial phase" — maximises APHE detection, which is the primary LI-RADS major criterion for HCC. The standard timing strategy uses automated bolus detection (test bolus or fluoroscopic triggering with a fixed delay of approximately 8–12 seconds after threshold detection in the aorta or portal vein). A fixed delay of 20–25 seconds post-injection is less reliable but acceptable when automated triggering is unavailable. Multi-arterial acquisition (2–3 rapid overlapping phases) substantially reduces the risk of missed arterial phase [11] and is the recommended strategy when gadoxetate is used.

The portal venous phase (60–70 seconds post-injection) provides washout assessment, portal vein opacification for portal thrombosis evaluation, and the primary acquisition for hypervascular tumour washout kinetics. It is the most motion-tolerant dynamic phase because the portal venous opacification window is 15–20 seconds wide.

The delayed/equilibrium phase (3–5 minutes for extracellular agents; 2–3 minutes for gadoxetate before transitional phase onset) demonstrates capsule enhancement (LI-RADS major feature), fibrous tissue enhancement, and confirms washout. With gadoxetate, the interpretation of washout and capsule on the delayed phase is complicated by the onset of hepatobiliary uptake in the transitional phase (2–5 minutes post-injection), which progressively increases parenchymal T1 signal and can simulate relative washout or modify lesion conspicuity [2, 3].

4.4 Sequence Matching and Cross-Sequence Consistency

All dynamic T1 3D phases (pre-contrast, late arterial, portal venous, delayed, and HBP) must use identical sequence parameters: same TR, TE, flip angle, FOV, matrix, slice positions, and slice thickness. Any geometric mismatch between phases invalidates subtraction and introduces misregistration artefacts that simulate or obscure enhancement.

The slice plan for T1 3D dynamic sequences should be prescribed from the pre-contrast T1 scan and locked for all subsequent phases. Patients who move between phases require manual correction of slice registration before interpretation — this is a technologist QC responsibility before ending the examination.

DWI slice positions should match the T1 axial prescription as closely as possible (identical inferior and superior extent) to enable reliable lesion co-registration across DWI and enhancement findings without reformatting.

For post-treatment protocols, the current examination's slice positions must be aligned with the prior examination to allow direct lesion comparison and accurate measurement of treatment effect.

4.5 Fat Suppression — Region-Specific Considerations

Fat suppression for hepatic T1 3D dynamic sequences is required to ensure that enhancing lesions are not obscured by adjacent perivascular fat and that hepatic parenchyma enhancement is interpretable against a suppressed fat background. The choice of fat suppression technique has significant quality implications in abdominal imaging:

Dixon fat suppression is the preferred technique for T1 3D dynamic liver sequences at both 1.5T and 3T. Dixon exploits the chemical shift between water and fat protons to produce simultaneous water-only and fat-only images via post-processing, providing B0-field-independent fat-water separation. This is particularly valuable at 3T where B0 inhomogeneity in the upper abdomen frequently degrades frequency-selective (spectral) fat suppression. Dixon also provides the fat quantification data needed for PDFF calculation when the appropriate multi-echo acquisition is used.

SPAIR (Spectral Attenuated Inversion Recovery) is a robust spectral fat suppression technique that is more homogeneous than CHESS/SPIR and is acceptable for hepatic sequences at 1.5T. At 3T, B0 inhomogeneity in the upper abdomen reduces SPAIR reliability, particularly near the dome and near metallic implants.

STIR should not be used for post-contrast T1 sequences because the inversion pulse nulls the signal of gadolinium-enhanced tissue (by shortening T1 toward the null point), producing paradoxical signal loss in enhancing lesions.

B0 shimming before the dynamic acquisition is essential at 3T for all spectral fat suppression methods. A dedicated manual or automated shim over the liver FOV should be performed before the pre-contrast T1 acquisition and maintained for all subsequent phases.

5. Optimisation Strategy

5.1 Artifact Reduction by Source

Transient Severe Motion (TSM) with gadoxetate: TSM is a gadoxetate-specific phenomenon in which the patient's breath-hold capacity transiently deteriorates during the arterial phase acquisition, producing severe motion blurring specifically on arterial images. The pooled incidence of TSM with single-phase arterial acquisition is approximately 13% [11]. The mechanism involves a transient reduction in serum phosphate induced by gadoxetate, causing respiratory muscle fatigue. Mitigation: (1) multi-arterial acquisition (2–3 rapid, short-duration arterial phases) is the most effective strategy, reducing TSM by distributing the risk across multiple acquisitions [11]; (2) coach patients to begin breath-hold at the verbal cue rather than attempting maximum inspiration; (3) keep arterial phase acquisition time ≤ 15 seconds; (4) use compressed sensing or parallel imaging to reduce individual phase duration; (5) use standard dose 0.025 mmol/kg — not higher doses.

Respiratory motion on T2 TSE and DWI: the dominant non-phase-specific artefact source in liver MRI. Strategies: respiratory triggering for T2 TSE (target 30–50% of respiratory cycle at expiration); navigator echo correction; PROPELLER/BLADE k-space for T2 in poor cooperators; for DWI, breath-triggered acquisition reduces motion between b-value acquisitions and improves ADC map quality.

EPI geometric distortion on DWI: EPI-based DWI in the upper abdomen is affected by B0 field inhomogeneity at air-tissue interfaces (stomach, bowel gas, lung bases) and at 3T in general. The left hepatic lobe adjacent to the gastric air bubble is particularly vulnerable. Mitigation: B0 shim optimised over the liver FOV before DWI; reduced EPI echo train length (higher bandwidth); parallel imaging acceleration reducing EPI readout length; post-processing distortion correction (B0 field map or reverse phase encoding). A small FOV DWI focused on the liver rather than the full abdomen reduces both acquisition time and distortion.

Fat suppression inhomogeneity: at 3T, B0 inhomogeneity in the upper abdomen produces regional fat suppression failure — typically at the liver dome, the posterior right lobe, and near the hepatic flexure. This appears as T1-bright fat in the suppression-failed regions, which can simulate haemorrhagic lesions or confound enhancement assessment. Mitigation: Dixon fat suppression (first choice); manual B0 shimming over the liver before the pre-contrast T1 scan; FOV adjustment to reduce shimming volume.

Susceptibility artefacts from biliary stents and surgical clips: metallic biliary stents and surgical clips from cholecystectomy or hepatic resection produce focal T2* signal loss. At 3T, the blooming effect is approximately 4× larger than at 1.5T. For patients with known biliary stents, 1.5T imaging may be preferable. When stents are present, note their location in the report and document the extent to which they degrade the adjacent biliary assessment.

Phase aliasing (wrap): insufficient FOV in the R-L direction produces aliasing of subcutaneous fat and lateral abdominal wall structures. In abdominal liver MRI, ensure FOV covers the full transverse diameter of the patient plus 2–3 cm margin. Phase oversampling (anti-aliasing) should be applied in the R-L direction when the patient is wide relative to the programmed FOV.

5.2 Protocol Efficiency and Throughput

A full multiparametric liver MRI with extracellular contrast can be completed in 30–35 minutes at 3T without HBP or MRCP. Adding gadoxetate HBP at 10–20 minutes extends the total to 40–55 minutes. Adding MRCP adds 5–10 minutes, regardless of contrast type.

The most time-efficient protocol uses compressed sensing (CS) or CAIPIRINHA-accelerated T1 3D for the dynamic phases, reducing each phase to 12–16 seconds — short enough for most patients to breath-hold reliably and enabling multi-arterial acquisition within the arterial window without extending total examination time.

Navigator-triggered T2 TSE adds 3–5 minutes over a breath-hold T2 acquisition but provides substantially higher image quality for lesion characterisation in patients with moderate breathing compliance.

For patients with very limited breath-holding capacity, a reduced protocol prioritising HASTE T2 + DWI + limited dynamic phases (arterial + portal) completed in ≤ 25 minutes is more diagnostically useful than a full protocol that generates non-diagnostic motion-degraded images.

5.3 Field Strength Considerations

1.5T: robust and reliable for liver MRI. Fewer artefacts from B0 inhomogeneity; better fat suppression homogeneity; lower susceptibility from bowel gas; less TSM risk with gadoxetate in some series. Standard for routine practice. Slightly lower SNR requires marginally longer acquisition times for equivalent resolution.

3T: higher intrinsic SNR allows higher spatial resolution within equivalent acquisition time, or equivalent quality at shorter scan time with greater parallel imaging acceleration. Preferred for lesion characterisation tasks requiring high spatial resolution (small lesion detection, capsule characterisation, HBP detail). The trade-offs are: greater B0 inhomogeneity requiring Dixon fat suppression; higher SAR limiting flip angles for long T2 sequences; greater susceptibility from biliary stents and metallic clips; potentially higher TSM risk with gadoxetate.

Clinical equivalence: the available comparative data show globally equivalent diagnostic performance between 1.5T and 3T for hepatic lesion detection and characterisation when both protocols are optimised [20]. The clinical decision between field strengths is primarily based on available equipment, specific clinical question (small lesion detection favours 3T), and patient factors (metallic implants, BMI).

The key practical message: at 1.5T, use optimised spectral fat suppression (SPAIR preferred over CHESS) or Dixon when available. At 3T, Dixon fat suppression for T1 dynamic sequences is the standard and the most important single field-strength adaptation.

6. Contrast Use Principles Specific to Liver MRI

6.1 Non-Contrast Standard Protocol — Sufficient For

The non-contrast liver MRI protocol (T2 single-shot + T2 TSE + T1 IP/OP + DWI) provides clinically useful information and is sufficient for:

• Simple hepatic cyst confirmation (T2 very bright, no restriction, no enhancement)
• Assessment of hepatic steatosis severity and distribution (T1 IP/OP, DWI as support)
• Hepatic iron quantification (T2* GRE or multi-echo T2* sequences)
• Biliary ductal assessment (MRCP without contrast)
• Patients with gadolinium contraindication (eGFR < 30 mL/min/1.73 m², documented allergy)
• Pregnancy where the clinical risk-benefit of gadolinium is unfavourable [22]
• Haematoma characterisation in a known acute context
• Screening DWI for lesion detection in high-volume oncology surveillance when a full protocol is logistically impractical

Non-contrast liver MRI is not sufficient for LI-RADS categorisation of hepatic nodules in cirrhotic patients, definitive characterisation of most solid lesions, or post-treatment LR-TR assessment.

6.2 Gadolinium Indicated — Region-Specific Contexts

Gadolinium-enhanced liver MRI is indicated for:

• All LI-RADS diagnostic categories (LR-1 through LR-M require enhancement data)
• Any solid or partially solid hepatic lesion requiring characterisation
• Hepatic metastases staging and treatment response assessment
• Post-locoregional therapy LR-TR assessment (enhancement data is mandatory for treatment response categorisation) [4, 6]
• Suspected hepatic abscess or inflammatory lesion (enhancement pattern distinguishes pyogenic abscess from amoebic abscess and from peripheral tumour necrosis)
• Biliary stricture assessment (MRCP + enhancement characterises mural enhancement suggesting cholangiocarcinoma)
• Vascular assessment (portal thrombosis: tumour vs. benign; hepatic vein assessment in Budd-Chiari)

Choice of agent — extracellular vs hepatobiliary:

Extracellular agents (gadoteridol, gadobutrol, gadoterate meglumine) provide the most straightforward dynamic characterisation with unambiguous washout assessment on delayed phases. They are the standard choice when the primary diagnostic question is HCC diagnosis by LI-RADS criteria in clinical contexts where washout interpretation must be unambiguous.

Hepatobiliary agents (gadoxetate disodium 0.025 mmol/kg; gadobenate dimeglumine 0.05–0.1 mmol/kg) add the HBP, which improves detection of sub-centimetre metastases [13], aids characterisation of FNH vs. adenoma, and provides biliary functional information [18, 21]. Meta-analytic data suggest that extracellular agents may provide higher sensitivity for HCC diagnosis when strict LI-RADS vascularity criteria are applied [12], while hepatobiliary agents provide superior metastasis detection. The choice should be driven by the primary clinical question, not by institutional default [3, 12, 24].

6.3 Post-Contrast Acquisition Timing

Late arterial phase: 8–12 seconds after automated bolus detection threshold, or 20–25 seconds after start of injection using fixed delay. The timing criterion is imaging when the hepatic arteries and portal vein are simultaneously opacified and the hepatic veins are not yet visible. This window is approximately 10–15 seconds wide.

Multi-arterial strategy (recommended with gadoxetate): acquire 2–3 consecutive arterial-phase volumes, each 10–15 seconds, starting from threshold + 5 seconds. The first phase may be early arterial (hepatic arteries only); the second will typically be the optimal late arterial phase; the third captures the transition to early portal. This strategy reduces the risk of TSM degrading the single critical arterial phase [11].

Portal venous phase: 60–70 seconds after start of injection. This timing is robust to minor variations.

Delayed/equilibrium phase:

• Extracellular agents: 3–5 minutes post-injection (equilibrium)
• Gadoxetate: 2–3 minutes post-injection (before significant HBP uptake alters parenchymal signal)
• Gadobenate used for HBP: equivalent to extracellular delayed phase (no transitional phase concern)

Hepatobiliary phase:

• Gadoxetate: 10–20 minutes post-injection; longer delays (20–30 minutes) in cirrhosis, cholestasis, or suspected hepatic dysfunction [19]
• Gadobenate: 60–120 minutes post-injection (logistically demanding; usually requires the patient to return or wait outside the scanner)

MRCP timing: always pre-contrast or, if in a gadoxetate protocol, at least 10–15 minutes post-injection when biliary contrast enhancement has occurred. The pre-contrast MRCP is preferred to avoid T1 signal contamination in the 3D MRCP acquisition.

Subtraction imaging: T1 post-contrast minus T1 pre-contrast subtraction is performed as standard post-processing in post-treatment protocols and whenever pre-treatment T1 signal is elevated (haemorrhage, gadolinium deposition, melanin, cholesterol). It should be generated at the time of examination and reviewed by the reporting radiologist.

7. Reporting Essentials

7.1 Interpretation Framework

Liver MRI reporting follows a structured multi-dimensional analysis that integrates findings from all sequences before reaching a conclusion. The reporting framework proceeds through five analytical axes:

Parenchymal background: before assessing individual lesions, characterise the background parenchyma — steatosis (T1 IP/OP signal drop), iron deposition (T2* and T1 signal behaviour), cirrhosis signs (surface nodularity on T2, left lobe hypertrophy, caudate lobe hypertrophy, segment IV atrophy, splenomegaly, porto-systemic collaterals, ascite). The parenchymal background determines the clinical population applicability of LI-RADS and modifies the pre-test probability for HCC.

Lesion inventory: systematically examine each Couinaud segment on T2 single-shot (sensitivity), T2 TSE (characterisation), DWI (small lesion detection), and T1 pre-contrast for T1-bright baseline lesions. The number, size, and location of all lesions must be documented before proceeding to characterisation.

Enhancement pattern analysis: for each lesion, apply the full dynamic analysis — APHE (present/absent), washout (definite/mild/absent), capsule (present/absent), arterial enhancement pattern (homogeneous vs. rim enhancement). Apply LI-RADS major and ancillary features systematically.

HBP interpretation (when available): lesion signal on HBP relative to background liver — hypointense (most malignancies, most benign lesions without hepatocyte function), isointense (some dysplastic nodules, some adenomas), or hyperintense (FNH, some HCC subtypes). Do not interpret HBP in isolation — a hypointense lesion on HBP is neither specific nor diagnostic for malignancy.

Biliary and vascular assessment: portal vein patency and any thrombosis (bland vs. tumour); hepatic vein patency; IVC assessment; biliary dilatation pattern and level; any biliary stricture morphology.

7.2 Mandatory Reporting Checklist

Technical quality assessment:

• State field strength, contrast agent, dose
• Note arterial phase quality (adequate/late arterial/non-diagnostic)
• Note motion artefacts limiting interpretation
• Note fat suppression quality
• Note HBP adequacy if applicable
• Note any sequences not performed and reason

Hepatic parenchyma:

• Liver size (at least craniocaudal span, or qualitative assessment)
• Signs of cirrhosis or chronic liver disease (surface nodularity, lobar atrophy, portal hypertension)
• Steatosis: absent/mild/moderate/severe (T1 IP/OP)
• Iron deposition: absent/present
• Post-treatment changes if applicable

For each lesion:

• Number (up to 4 for LI-RADS; "too numerous to count" if applicable)
• Size (longest diameter)
• Couinaud segment and sub-location (subcapsular, hilar, dome, proximity to hepatic veins)
• T2 signal (hypointense/isointense/mildly/markedly hyperintense)
• T1 pre-contrast signal
• DWI/ADC: restricted/not restricted (ADC value optional but recommended)
• APHE: definite/not definite
• Washout: definite/not definite
• Capsule: present/absent
• HBP appearance (if hepatobiliary agent used)
• Other LI-RADS ancillary features relevant to the lesion
• LI-RADS category (in applicable population) or descriptive characterisation

Biliary system:

• Intrahepatic biliary dilatation: present/absent; level
• Common bile duct diameter and any filling defects
• Gallbladder status

Vascular structures:

• Portal vein patency; any thrombosis (bland vs. tumour)
• Hepatic veins: patent/abnormal
• Retrohepatic IVC

Extrahepatic findings in field of view:

• Ascites
• Splenomegaly
• Lymphadenopathy (hepatic hilum, portocaval, para-aortic)
• Incidental extrahepatic findings

7.3 Structured Reporting

All liver MRI reports should follow this structure:

Indication: primary clinical question; relevant history (cirrhosis, known malignancy, prior treatment, index lesion).

Technique: field strength; coil; sequences performed; contrast agent (type, dose, route); any modifications from standard protocol; quality assessment (good/adequate/limited and reason).

Comparison: prior imaging (date, modality, key findings for comparison).

Findings: organised by the categories above (parenchyma → lesions → biliary → vascular → extra-hepatic).

Impression: concise diagnostic conclusion addressing the clinical question directly. Apply LI-RADS category for all lesions in at-risk patients. State explicitly whether LI-RADS criteria are applicable (cirrhotic patient under surveillance) or not.

Recommendation: management suggestion — surveillance interval, repeat MRI timing, biopsy, multidisciplinary team discussion, CT correlation, no further imaging.

Limitations: explicitly state any technical limitations affecting diagnostic confidence.

7.4 Incidental Findings — Clinical Decision Framework

Usually benign, no action required: simple hepatic cysts (T2 very bright, no wall, no enhancement); haemangioma with typical features (T2 markedly hyperintense, peripheral nodular enhancement, progressive fill-in); segment IV fatty deposition (T1 IP/OP); incidental small gallstones.

Requires documentation and clinical correlation: renal lesions (Bosniak classification if complex); adrenal nodules (> 1 cm require characterisation protocol); pancreatic lesions > 5 mm; splenomegaly without explanation; pericardial effusion; pleural effusion.

Requires urgent communication or specific action: unexpected portal vein thrombosis in a non-cirrhotic patient; unexpected biliary obstruction with mural enhancement suggesting cholangiocarcinoma; unexpected solid pancreatic lesion; unexpected lymphadenopathy pattern suggesting lymphoma; unsuspected advanced cirrhosis with portal hypertension features in a patient referred without known liver disease.

8. MRI Technologist Pearls

8.1 Sequence Order Logic

The sequence order for liver MRI is not arbitrary — it is designed to maximise diagnostic value, manage contrast timing, and account for patient fatigue and respiratory compliance:

1. Localiser (three-plane)
2. T2 HASTE/SSFSE (motion-resistant baseline; should be early while patient is alert)
3. T2 TSE respiratory-triggered/navigator (longer acquisition; requires patient compliance)
4. T1 IP/OP dual-echo (pre-contrast T1 baseline; quick; pre-contrast mandatory)
5. DWI (pre-contrast; ADC not affected by gadolinium)
6. MRCP (if indicated; always pre-contrast for biliary opacification clarity)
7. Pre-contrast T1 3D FS (locked reference for subtraction and dynamic comparison)
8. Contrast injection (power injector; saline flush)
9. Dynamic phases: late arterial → portal venous → delayed
10. HBP (gadoxetate: 10–20 min wait; gadobenate: 60–120 min)

The placement of MRCP before contrast is critical — post-contrast MRCP is degraded by T1 gadolinium signal in the biliary tree (for hepatobiliary agents) and by the bowel enhancement that reduces fluid-to-background contrast.

The DWI is placed pre-contrast because in gadoxetate protocols, T2 and DWI can alternatively be moved to after the delayed phase (while waiting for HBP), which optimises total examination time — but only in cooperative patients who maintain consistent position throughout [2]. Document the strategy used in the report.

8.2 Positioning Tricks

For patients with limited arm elevation tolerance, placing the arms at the sides increases susceptibility to aliasing in the R-L direction and may require increased FOV or phase oversampling. Consider elevating only the right arm if partial arm elevation is possible.

For markedly obese patients (BMI > 35 kg/m²): (1) prioritise Dixon fat suppression — spectral fat suppression will be inhomogeneous; (2) consider increasing parallel imaging factor to reduce acquisition time per phase and thus reduce breath-hold duration; (3) position the patient slightly decubitus right if needed to avoid the liver slipping under the coil edge; (4) at 1.5T, SNR is more adequate for obese patients than at 3T despite the theoretical SNR disadvantage.

For patients with tense ascites: the liver is displaced medially and anteriorly. Adjust centring to ensure the full liver — which may be partially displaced into the mid-abdomen — is within coverage. Check inferior coverage on the localiser specifically.

8.3 Fast Salvage Protocol

For patients with severely limited breath-holding capacity (< 10 seconds) or severe claustrophobia requiring rapid examination:

This 10–13 minute abbreviated protocol provides sufficient information to: detect most lesions > 1 cm; confirm simple cysts; detect diffuse parenchymal disease; identify portal vein thrombosis. It does not provide adequate information for LI-RADS categorisation or precise HCC characterisation.

8.4 Common Avoidable Errors

9. Quality Control Checklist

• Complete liver coverage: hepatic dome (superior) through inferior tip of segment VI/III
• Portal vein bifurcation and hepatic vein confluence both visible on axial T1
• T2 HASTE: acceptable quality despite motion; cysts clearly identified
• T2 TSE: navigator-triggered or breath-hold; adequate T2 characterisation quality
• T1 IP/OP: both phases geometrically matched; signal drop on OP for fat-containing lesions if present
• DWI: acceptable distortion (posterior segments not displaced); ADC map generated; b-value scheme documented
• Pre-contrast T1 3D FS: fat suppression homogeneous or Dixon in use; no aliasing
• Late arterial phase: simultaneous hepatic artery + portal vein opacification; hepatic veins not yet visible; no TSM
• Portal venous phase: portal vein + hepatic veins both opacified; adequate parenchymal enhancement
• Delayed phase: capsule assessment feasible; washout assessment feasible
• HBP (if applicable): parenchymal uptake present; biliary opacification visible in segment I–VIII bile radicles (if function preserved)
• Subtraction available if pre-contrast T1 signal elevated or post-treatment protocol
• MRCP (if performed): ductal morphology visible; no significant signal contamination
• All phases geometrically matched to pre-contrast T1 (within 2–3 mm)
• Phase encoding direction documented for QC reproducibility
• Patient breath-hold quality documented in protocol notes

11. Evidence Gaps and Ongoing Debate

12. Evidence-Based References

A. Guidelines / Consensus / Society Recommendations

B. Systematic Reviews / Meta-analyses

C. Important Prospective / Original Studies

D. Technical MRI Papers

End of document — MRI Liver Generic Standard Protocol — MRIninja v1.0 — May 2026 This master page is the reference for all future liver MRI child pages including: HCC/LI-RADS child protocol; hepatic metastases child protocol; biliary obstruction/MRCP child protocol; post-locoregional therapy LR-TR protocol; abbreviated MRI surveillance protocol; MRE/fibrosis quantification protocol.