Liver MRI Protocol Research Articles

Diagnostic accuracy of an uncorrected native T1 mapping sequence for liver fibrosis and inflammation in autoimmune hepatitis: a prospective study using histopathology as reference standard.

There is an unmet clinical need for non-invasive imaging biomarkers that could replace liver biopsy in the management of patients with autoimmune hepatitis (AIH). In this study, we sought to evaluate the diagnostic accuracy of a simple uncorrected, non-contrast T1 mapping for detecting fibrosis and inflammation in AIH patients using histopathology as a reference standard. Over 3years, 33 patients with AIH were prospectively studied using a multiparametric liver MRI protocol which included T1 mapping. Biopsies were performed up to 3months before imaging, and a standardized histopathological score for fibrosis (F0-F4) and inflammatory activity (PPA0-4) was used as a reference. Statistical analysis included independent t test, Mann-Whitney U-test, and ROC (receiver operating characteristic) analysis. T1 mapping values were significantly higher in patients with advanced fibrosis (F0-2 vs. F3-4; p < 0.015), significant fibrosis (F0-1 vs. F2-4; p < 0.005), and significant inflammatory activity (PPA 0-1 vs. PPA 2-4 p = 0.048). Moreover, the technique demonstrated a good diagnostic performance in detecting significant (AUC 0.856) and advanced fibrosis (AUC 0.835), as well as significant inflammatory activity (AUC 0.763). A rapid, simple, uncorrected, non-contrast T1 mapping sequence showed satisfactory diagnostic performance in comparison with histopathology for detecting significant tissue inflammation and fibrosis in AIH patients, being a potential non-invasive imaging biomarker for monitoring disease activity in such individuals.

Estimation of Optimum Flip Angle using 3D VANE XD Technique: Focused on Pre-Contrast and Hepatobiliary Phase

To investigate the optimum flip angle that can enhance image quality, SNR (signal to noise ratio), and CNR (contrast to noise ratio), comparing the images obtained, applying flip angles, 11°, 14°, 17°, 20°, and 23° in getting Liver Hepatobiliary Phase image using 3D VANE XD(3D Multivane mDixon, Philips Healthcare) technique. Experiments were conducted on a total of 30 outpatients and inpatients to our hospital (HCC:10, Metastasis:10, Abscess:10). As for the equipment used in the experiments, Philips Ingenia 3.0T CX was used, and all parameters other than the flip angle were set the same to conduct the tests. As for the image analysis method, using the Image-J program (National Institutes of Health and LOCI), the SNR of the liver, kidney, and pancreas obtained from the images by flip angle before the contrast medium injection and the CNR between the lesion and the normal tissue after the contrast medium injection were measured to conduct comparative analysis. As a result of a comparison of images before and after the contrast medium injection by disease, when the flip angle of 17° was applied, SNR and CNR were measured higher than in the images of other flip angles (p0.05). In the comparisons of the images taken before and after the injection of contrast medium by disease, when a flip angle of 17° was applied, the SNR before contrast medium injection was 28-29 % higher, and the SNR after the injection of contrast medium was 11 % up to 49 % higher than that at other flip angles. There was a difference in CNR before contrast medium injection of 30-43 % and CNR after contrast medium injection of 58-68 %. The measured value increased up to 17° and then decreased after that. Additionally, in the qualitative evaluation, Lesion Conspicuity (p=0.003), Image Artifact (p=0.0001), Lesion Delineation (p=0.0002), and Vascular Anatomy (p=0.0002) received the most excellent evaluations at 17°. In conclusion, in this study, the flip angle of 17° provided the highest SNR and CNR values when the tests were conducted using the free breath hold technique, 3D VANE XD Sequence. Thus, in liver MRI protocol tests, the overall diagnostic information was provided, including hypervascular tumor.

Perfusion-Diffusion Ratio: A New IVIM Approach in Differentiating Solid Benign and Malignant Primary Lesions of the Liver.

Introduction In order to improve the efficacy of intravoxel incoherent motion (IVIM) parameters in characterising specific tissues, a new concept is introduced: the perfusion–diffusion ratio (PDR), which expresses the relationship between the signal S(b) decline rate as a result of IVIM and the rate of signal S(b) decline due to diffusion. The aim of this study was to investigate this novel approach in the differentiation of solid primary liver lesions. Material and Methods. Eighty-three patients referred for liver MRI between August 2017 and January 2020 with a suspected liver tumour were prospectively examined with the standard liver MRI protocol extended by DWI-IVIM sequence. Patients with no liver lesions, haemangiomas, or metastases were excluded. The final study population consisted of 34 patients with primary solid liver masses, 9 with FNH, 4 with regenerative nodules, 10 with HCC, and 11 with CCC. The PDR coefficient was introduced, defined as the ratio of the rate of signal S(b) decrease due to the IVIM effect to the rate of signal S(b) decrease due to the diffusion process, for b = 0. Results No significant differences were found between benign and malignant lesions in the case of IVIM parameters (f, D, or D∗) and ADC. Significant differences were observed only for PDR, with lower values for malignant lesions (p = 0.03). The ROC analysis yielded an AUC value for PDR equal to 0.74, with a cut-off value of 5.06, sensitivity of 81%, specificity of 77%, and accuracy of 79%. Conclusion PDR proved to be more effective than IVIM parameters and ADC in the differentiation of solid benign and malignant primary liver lesions.

Diagnostic accuracy of different magnetic resonance imaging sequences for detecting local tumor progression after radiofrequency ablation of hepatic malignancies

ObjectiveTo evaluate the diagnostic accuracy of the individual sequences of a clinical routine liver MRI protocol for the detection of local tumour progression after radiofrequency (RF) ablation of hepatic malignancies. Material and methodsA cohort of 93 patients treated for 140 primary and secondary hepatic malignancies with RF ablation was assembled for this retrospective study. The cohort contained 31 cases of local tumour progression, which occurred 8.3±6.2months (range: 4.0–28.2 months) after treatment. All patients underwent clinical routine follow-up MRI at 1.5T including following sequences: unenhanced T1-weighted fast low angle shot (FLASH-2D), T2-weighted turbo-spin-echo sequence, contrast-enhanced (CE) T1-weighted volume-interpolated breath-hold examination (VIBE), diffusion-weighted imaging (DWI). Follow-up was 32.7±22.5months (range: 4.0–138.3 months). Two readers independently evaluated the individual sequences separately for signs of local tumour progression. Diagnostic confidence was rated on a 4-point scale. Inter-reader agreement was assessed with Coheńs kappa. Long-term follow-up and histological specimen served as standard of reference. ResultsBoth readers reached the highest sensitivity for detection of local tumour progression with unenhanced T1-FLASH 2D (88.2% and 94.1%, respectively) and the highest specificity with CE T1-VIBE (96.2% and 97.2%, respectively). Highest inter-reader agreement was reached with T1-FLASH-2D (kappa=0.83). Typical pitfalls for false-positive diagnoses were focal cholestasis and vasculature adjacent to the ablation zone. Diagnostic confidence was highest with CE T1-VIBE for reader 1 and DWI for reader 2. ConclusionUnenhanced T1-FLASH-2D is an essential sequence for follow-up imaging after tumour ablation with a high sensitivity for detection of local progression and a high inter-reader agreement.

Half-dose gadobenate dimeglumine versus standard-dose gadodiamide in dynamic magnetic resonance imaging of non-cirrhotic livers: a retrospective intra-individual crossover comparison

The purpose of this study was to compare enhancement characteristics of half-dose gadobenate dimeglumine (0.05mmolkg(-1)) with standard-dose gadodiamide (0.10mmolkg(-1)), in the assessment of hepatic vessels and lesions, using retrospective intra-individual crossover comparison methodology. Ethics committee approval was obtained. From 2004 to 2012, 21 patients underwent MRI examination with both standard-dose gadodiamide and half-dose gadobenate dimeglumine, using the same liver MRI protocol at 1.5T. Eighteen patients whose scans showed no artifacts were selected. Quality of liver lesion [12 hemangiomas, 7 focal nodular hyperplasias (FNHs)] and liver vessel enhancement, and the global diagnostic quality of studies were ranked on a scale of 1-4 by two independent radiologists. Contrast-to-noise ratio (CNR) and % enhancement of liver vessels and lesions were calculated based on region of interest, signal intensity, and noise standard deviation measurements performed at 0, 20s, 1, 3, and 5min post-contrast injection. Qualitative and quantitative results were compared using the paired Wilcoxon signed rank and Student's t-tests, respectively. No qualitative differences were noted in enhancement of liver vessels, hemangiomas, and FNHs. There was no statistically significant difference between the global diagnostic qualities of scans performed with the two contrast agents. Quantitatively, liver vessels and hemangiomas did not demonstrate statistically significant differences in contrast enhancement. At 20s, FNHs achieved higher CNR (P=0.02) with gadodiamide. Half-dose gadobenate dimeglumine results in similar contrast enhancement compared to standard-dose gadodiamide in assessment of liver vessels, hemangiomas, and FNHs, and is a reasonable alternative to standard doses of extracellular agents in dynamic liver MRI.

Automated Patient-Tailored Screening of the Liver for Diffuse Steatosis and Iron Overload Using MRI

The purpose of this article is to validate an automated screening method for evaluation of hepatic steatosis or siderosis. This was a two-part study, with retrospective and prospective portions. First, 130 consecutive abdominal MRI examinations, including both the automated algorithm and reference standard fat and iron quantification, were retrospectively identified. The algorithm's performance was validated against the reference standard and was compared with the performance of three expert readers. Subsequently, 39 subjects undergoing liver MRI were prospectively identified and enrolled. These subjects were scanned with a protocol where quantification sequences were either performed or not performed on the basis of the recommendation of the algorithm. Total examination time in these subjects was compared with examination times in the 90 subjects from the retrospective cohort who had undergone a similar liver MRI protocol with complete quantification. The automated algorithm was accurate in determining the presence of deposition disease (93.1%), with no significant difference between its conclusions and those of any of the readers (p=0.48-1.0). Use of the algorithm resulted in a small but statistically significant time savings compared with performing quantification in all subjects (28 minutes 56 seconds vs 31 minutes 20 seconds; p<0.05). Automated screening for hepatic steatosis and siderosis can be performed in real time during abdominal MRI examinations, can save total scan time compared with always performing quantification, and could serve as a gatekeeper for dedicated quantification sequences.

Diagnostic accuracy of diffusion-weighted MRI for identifying hepatocellular carcinoma with liver explant correlation

The goal of this study was to use liver explant correlation to assess the diagnostic accuracy of diffusion-weighted (DW)-MRI for hepatocellular carcinoma (HCC). Thirty-seven patients were retrospectively identified who had undergone liver transplantation and had preoperative, respiratory-triggered, single-shot echo-planar DW-MRI. Two independent blinded observers evaluated the DW-MRI images for HCC and comparison was made with the explanted specimens. By pathology, 29 HCCs (mean largest diameter 2.0 cm; range 0.7-4.0 cm) were identified in 20 patients. Sensitivity and specificity for reader 1 were 55 and 92%, and for reader 2 were 45 and 100%. There was 'substantial' inter-observer agreement (kappa = 0.64). DW-MR is not sensitive enough for HCC to be used as a stand-alone sequence, although its high specificity suggests that it is likely valuable as a component of a liver MRI protocol.

Assessment of the diagnostic accuracy of T2*-weighted MR imaging for identifying hepatocellular carcinoma with liver explant correlation

T2*-weighted MRI may represent a novel method for identifying hepatocellular carcinoma (HCC). The goal of this study was to assess the diagnostic accuracy of T2*-weighted MRI for HCC with liver explant correlation. A retrospective review identified 25 patients who had undergone liver transplantation with pre-operative T2*-weighted MRI. All patients had Child's-Pugh A (9), B (9), or C (7) liver disease with 13 transplanted for liver dysfunction and 12 for HCC. The T2*-weighted images were interpreted by 2 blinded, independent observers and the results compared with the explanted specimens. Sensitivity and specificity of T2*-weighted MRI for the identification of HCC was assessed. By pathology, 16 HCC (mean largest diameter 2.1 cm; range 0.9-3.6 cm) were identified in 14 patients. Reader 1 had a sensitivity of 69% (95% confidence interval 41-88%) and a specificity of 100% (68-100%). Reader 2 had a sensitivity of 56% (31-79%) and a specificity of 100% (68-100%). There was a very good inter-observer agreement (kappa=0.84). T2*-weighted MRI had a moderate sensitivity for identifying HCC but had an excellent specificity. A T2*-weighted MR sequence may be a useful component of a liver MRI protocol due to its high specificity for HCC, and may be particularly useful in patients unable to undergo gadolinium enhanced MRI.