Portal hypertension may influence the registration of hypointensity of small hepatocellular carcinoma in the hepatobiliary phase in gadoxetic acid MR.

BACKGROUND: The aim of the study was to analyze the association between the liver uptake of Gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) in the hepatobiliary phase (HBP) in cirrhotic patients and the presence of clinically significant portal hypertension (CSPH), and how these features impact on hepatocellular carcinoma (HCC) detection in the HBP. PATIENTS AND METHODS: Post-hoc analysis of a prospective cohort of 62 cirrhotic patients with newly US-detected nodule between 1-2 cm (study group). Twenty healthy subjects were used as control group. Qualitative and quantitative analysis of the liver contrast uptake in the HBP assessed by Relative Liver-Enhancement (RLE), Liver-Spleen (LSCR), Liver-Muscle (LMCR), and Liver-Kidney Contrast-Ratio (LKCR), Contrast Enhancement Index (CEI), and Hepatic Uptake (HUI), and biliary excretion, were registered. CSPH was confirmed invasively (HVPG > 10 mmHg) or by indirect parameters. The appearance of HCC at the HBP was analyzed. RESULTS: Nineteen patients (30.6%) did not have CSPH. In 41 patients (66.1%) the final diagnosis was HCC. All indices were significantly higher in the control group, indicating a more intense HBP liver signal intensity compared to patients with cirrhosis, even if the comparison was restricted to patients with no CSPH. CSPH was associated to a lower rate of HCC hypointensity in the HBP (51.9% vs. 85.7% without CSPH, p = 0.004). CONCLUSIONS: Liver uptake of Gd-EOB-DTPA at the HBP is decreased in cirrhosis even if the liver function is minimally impaired and it falls down significantly in patients with CSPH compromising the recognition of hypointense lesions. This fact may represent a limitation for the detection of small HCC in patients with cirrhosis and CSPH.

Evaluation of LI-RADS 3 category by magnetic resonance in US-detected nodules ≤ 2 cm in cirrhotic patients.

OBJECTIVES: Liver Imaging Reporting and Data System (LI-RADS) for hepatocellular carcinoma (HCC) diagnosis in high-risk patients is a dynamic system, which was lastly updated in 2018. We aimed to evaluate the accuracy for HCC diagnosis of LI-RADS v2018 with magnetic resonance imaging (MRI) with extracellular contrast for solitary nodules ≤ 20 mm detected during ultrasound (US) surveillance in cirrhotic patients, with particular interest in those observations categorized as LI-RADS 3. METHODS: Between November 2003 and February 2017, we included 262 consecutive cirrhotic patients with a newly US-detected solitary ≤ 20-mm nodule. A LI-RADS (LR) v2018 category was retrospectively assigned. The diagnostic accuracy for each LR category was described, and the main MRI findings associated with HCC diagnosis were analyzed. RESULTS: Final diagnoses were as follows: 197 HCC (75.2%), 5 cholangiocarcinoma (1.9%), 2 metastasis (0.8%), and 58 benign lesions (22.1%); 0/15 (0%) LR-1, 6/26 (23.1%) LR-2, 51/74 (68.9%) LR-3, 11/12 (91.7%) LR-4, 126/127 (99.2%) LR-5, and 3/8 (37.5%) LR-M were HCC. LR-5 category displayed a sensitivity and specificity of 64% (95% CI, 56.8-70.7) and 98.5% (95% CI, 91.7-100), respectively. Considering also LR-4 as diagnostic for HCC, the sensitivity slightly increased to 69.5% (95% CI, 62.6-75.9) with minor impact on specificity (96.2%; 95% CI, 89.3-99.6). Regarding LR-3 observations, 51 out of 74 were HCC, 2 were non-HCC malignancies, and 20 out of 21 LR-3 nodules > 15 mm (95.2%) were finally categorized as HCC. CONCLUSIONS: The high probability of HCC in US-detected LR-3 observations (68.9%) justifies triggering an active diagnostic work-up if intended to diagnose HCC at a very early stage. KEY POINTS: • In cirrhotic patients with nodules ≤ 20 mm detected during US surveillance, 51 out of 74 (68.9%) of LR-3 nodules by MRI corresponded to an HCC. • In LR-3 nodules, HCC diagnosis was closely related to baseline tumor size. All 5 nodules smaller than 1 cm were diagnosed as benign. Oppositely, 20 out of 21 LR-3 observations > 15 mm (95.2%) were diagnosed as HCC. • The high probability of HCC in US-detected LR-3 observations justifies triggering an active diagnostic work-up if intended to diagnose HCC at a very early stage.

Does transient arterial-phase respiratory-motion-related artifact impact on diagnostic performance? An intra-patient comparison of extracellular gadolinium versus gadoxetic acid.

OBJECTIVE: To compare the frequency of transient arterial-phase respiratory-motion-related artifacts in liver MRI after extracellular gadolinium and gadoxetic acid injection, and to determine the impact of these artifacts on the detection of focal areas of enhancement on arterial-phase images. MATERIALS AND METHODS: Intra-patient comparison of 82 cirrhotic patients who prospectively underwent liver MR with extracellular gadolinium and with gadoxetic acid within 1 month. Two readers independently assessed the quality of dynamic T1-weighted MR images (pre-contrast, arterial, and portal-venous phases), rating respiratory-motion-related artifacts on four-point scale (0 [none]-3 [non-diagnostic]). We dichotomized these assessments, which were compared using McNemar's test, defining transient arterial-phase respiratory-motion-related artifacts as a study with a pre-contrast score < 2 and arterial-phase score ≥ 2. Readers also recorded whether at least one focal area of enhancement ≥ 10 mm on arterial phase was present. RESULTS: The quality of arterial-phase images was worse when obtained after gadoxetic acid than after extracellular gadolinium (p < 0.01), and transient arterial-phase respiratory-motion-related artifacts were more common after gadoxetic acid than after extracellular gadolinium (p < 0.02). At least one area of arterial-phase enhancement ≥ 10 mm was detected more often after extracellular gadolinium than after gadoxetic acid. We observed significant differences on the comparison of the distributions of the presence of arterial-phase artifacts against the presence of arterial-phase enhancement ≥ 10 mm between the two contrast agents (p < 0.0001). CONCLUSION: In cirrhotic patients, transient arterial-phase respiratory-motion-related artifacts are more common after gadoxetic acid than after extracellular gadolinium. Worse detection of arterial-phase enhancement on gadoxetic acid is only partly due to these artifacts. KEY POINTS: • In a patient-by-patient analysis, the quality of arterial-phase liver MR images was significantly worse with gadoxetic acid than with extracellular gadolinium. • The frequency of transient arterial-phase artifacts was significantly higher after gadoxetic acid injection than after extracellular gadolinium injection. • Differences in the detection of areas of arterial-phase enhancement between MRI studies done with extracellular gadolinium and those done with gadoxetic acid might not be related only to image quality.

Diagnosis and staging of hepatocellular carcinoma (HCC): current guidelines.

One of the key strategies to improve the prognosis of HCC, beside prevention, is to diagnose the tumor in early stages, when the patient is asymptomatic and the liver function is preserved, because in this clinical situation effective therapies with survival benefit can be applied. Imaging techniques are a key tool in the surveillance and diagnosis of HCC. Screening should be based in US every 6 months and non-invasive diagnostic criteria of HCC based on imaging findings on dynamic-MR and/or dynamic-CT have been validated and thus, accepted in clinical guidelines. The typical vascular pattern depicted by HCC on CT and or MRI consists on arterial enhancement, stronger than the surrounding liver (wash-in), and hypodensity or hyposignal intensity compared to the surrounding liver (wash-out) in the venous phase. This has a sensitivity of around 60% with a 96-100% specificity. Major improvements on liver imaging have been introduced in the latest years, adding functional information that can be quantified: the use of hepatobiliary contrast media for liver MRI, the inclusion of diffusion-weighted sequences in the standard protocols for liver MRI studies and new radiotracers for positron-emission tomography (PET). However, all them are still a matter of research prior to be incorporated in evidence based clinical decision making. This review summarizes the current knowledge about imaging techniques for the early diagnosis and staging of HCC, and it discusses the most relevant open questions.