〈Original〉MR cholangiopancreatography; Predicting imaging findings for differentiation of malignant bile ductal obstruction versus benign lesion

[Abstract]The purpose of the current study was to evaluate the use of magnetic resonance imaging (MRI) in conjunction with a scoring system to differentiate between malignant and benign strictures of the common bile duct. MRI scans of 54 patients with indeterminate biliary strictures on prior imaging were reviewed, and non-enhanced MRI, magnetic resonance cholangiopancreatography (MRCP), and diffusion-weighted imaging were analyzed. Eight radiologic parameters were significantly associated with malignancy; luminal irregularity, high signal intensity on diffusionweighted MRI, luminal stenosis asymmetry, T2-weighted MRI signal intensity, abrupt stenosis,bile duct dilatation ≥ 12.5 mm, stenosis length ≥ 10.5 mm, and wall thickness ≥ 4.5 mm. A simple system scoring based on statistically significant findings was developed, where each of the above findings counts for one point. A score of 6 or higher was found only in patients with a malignant stricture of the common bile duct; 60% of patients with a benign stenosis had a score of 1,or 2, and all patients with benign lesions had scores of less than 5. This MRI scoring system can assist in the differential diagnosis of common bile duct stricture with high accuracy; to be widely applicable, the MRI score needs to be validated in a prospective patient population

Comparative study of sub-second temporal resolution 4D-MRI and 4D-CT for target motion assessment in a phantom model

Abstract To develop and investigate the feasibility of sub-second temporal resolution volumetric T1-weighted four-dimensional (4D-) MRI in comparison with 4D-CT for respiratory-correlated motion assessment using an MRI/CT-compatible phantom. Sub-second high temporal resolution (0.5 s) gradient-echo T1-weighted 4D-MRI was developed using a volumetric acquisition scheme with compressed sensing. An MRI/CT-compatible motion phantom (simulated liver tumor) with three sinusoidal movements of amplitudes and two respiratory patterns was introduced and imaged with 4D-MRI and 4D-CT to investigate the geometric accuracy of the target movement. The geometric accuracy, including centroid position, volume, similarity index of dice similarity coefficient (DSC), and Hausdorff distance (HD), was systematically evaluated. Proposed 4D-MRI achieved a similar geometric accuracy compared with 4D-CT regarding the centroid position, volume, and similarity index. The observed position differences of the absolute average centroid were within 0.08 cm in 4D-MRI and 0.03 cm in 4D-CT, less than the 1-pixel resolution for each modality. The observed volume difference in 4D-MRI/4D-CT was within 0.73 cm3 (4.5%)/0.29 cm3 (2.1%) for a large target and 0.06 cm3 (11.3%)/0.04 cm3 (11.6%) for a small target. The observed DSC values for 4D-MRI/4D-CT were at least 0.93/0.95 for the large target and 0.83/0.84 for the small target. The maximum HD values were 0.25 cm/0.31 cm for the large target and 0.21 cm/0.15 cm for the small target. Although 4D-CT potentially exhibit superior numerical accuracy in phantom studies, the proposed high temporal resolution 4D-MRI demonstrates sub-millimetre geometric accuracy comparable to that of 4D-CT. These findings suggest that the 4D-MRI technique is a viable option for characterizing motion and generating phase-dependent internal target volumes within the realm of radiotherapy

How reader perception of capsule affects interpretation of washout in hypervascular liver nodules in patients at risk for hepatocellular carcinoma.

PurposeTo determine whether reader perception of a capsule affects reader interpretation of washout in hypervascular liver nodules at dynamic magnetic resonance imaging (MRI) in patients at risk for hepatocellular carcinoma (HCC).Materials and methodsThis retrospective study was Institutional Review Board (IRB)-approved and Health Insurance Portability and Accountability Act (HIPAA)-compliant, with waiver of informed consent. MRI reports for 111 hypervascular liver nodules (median 2.0 cm, range 1.0-17.8 cm) in 62 patients were reviewed, and the presence/absence of capsule and washout were recorded for one reading. A second independent study reading was also performed. The signal intensity ratio (SIR) for each nodule and liver parenchyma was measured. An objective SIR threshold was identified for nodules without capsules that correctly classified the presence/absence of washout, then applied to nodules with capsules to classify them as having / not having objective washout. Nodules were categorized as definite / not definite HCC using subjective and objective washout, based on LI-RADS, OPTN, AASLD, and EASL criteria, and proportions compared using McNemar's test.ResultsAgreement on nodule features was high for Readings 1 and 2 (κ = 0.70-0.82). For Reading 1, 71 nodules lacked capsules (43 with and 28 without subjective washout); an SIR threshold of 0.88 classified the presence/absence of washout correctly in 94% (67/71, P < 0.001). Forty nodules had capsules; although all had subjective washout (100%, 40/40), 75% (30/40) had objective washout (P < 0.05). Using objective washout caused 4.5% (3/66; LI-RADS, OPTN) and 12% (10/83; AASLD, EASL) of nodules to be recategorized from definite HCC to not definite HCC.ConclusionReader perception of capsule affects interpretation of washout. This effect can influence nodule categorization using imaging-based diagnostic systems. J. Magn. Reson. Imaging 2016;43:1337-1345

How reader perception of capsule affects interpretation of washout in hypervascular liver nodules in patients at risk for hepatocellular carcinoma.

PurposeTo determine whether reader perception of a capsule affects reader interpretation of washout in hypervascular liver nodules at dynamic magnetic resonance imaging (MRI) in patients at risk for hepatocellular carcinoma (HCC).Materials and methodsThis retrospective study was Institutional Review Board (IRB)-approved and Health Insurance Portability and Accountability Act (HIPAA)-compliant, with waiver of informed consent. MRI reports for 111 hypervascular liver nodules (median 2.0 cm, range 1.0-17.8 cm) in 62 patients were reviewed, and the presence/absence of capsule and washout were recorded for one reading. A second independent study reading was also performed. The signal intensity ratio (SIR) for each nodule and liver parenchyma was measured. An objective SIR threshold was identified for nodules without capsules that correctly classified the presence/absence of washout, then applied to nodules with capsules to classify them as having / not having objective washout. Nodules were categorized as definite / not definite HCC using subjective and objective washout, based on LI-RADS, OPTN, AASLD, and EASL criteria, and proportions compared using McNemar's test.ResultsAgreement on nodule features was high for Readings 1 and 2 (κ = 0.70-0.82). For Reading 1, 71 nodules lacked capsules (43 with and 28 without subjective washout); an SIR threshold of 0.88 classified the presence/absence of washout correctly in 94% (67/71, P < 0.001). Forty nodules had capsules; although all had subjective washout (100%, 40/40), 75% (30/40) had objective washout (P < 0.05). Using objective washout caused 4.5% (3/66; LI-RADS, OPTN) and 12% (10/83; AASLD, EASL) of nodules to be recategorized from definite HCC to not definite HCC.ConclusionReader perception of capsule affects interpretation of washout. This effect can influence nodule categorization using imaging-based diagnostic systems. J. Magn. Reson. Imaging 2016;43:1337-1345

Mid-term Outcomes and Predictors of Transarterial Embolization for Type II Endoleak After Endovascular Abdominal Aortic Aneurysm Repair

Purpose To evaluate the mid-term outcomes of transarterial embolization (TAE) for type II endoleak after endovascular abdominal aortic aneurysm repair (EVAR) and investigate the predictors of sac enlargement after embolization. Materials and Methods We conducted a retrospective analysis of 55 patients [48 men and 7 women, median age 79.0 (interquartile ranges 74-82) years] who underwent TAE for type II endoleak from 2010 to 2018. The aneurysmal sac enlargement, endoleaks, aneurysm-related adverse event rate, and reintervention rate were evaluated. Patients' characteristics and clinical factors were evaluated for their association with sac enlargement. Results Fifty-five patients underwent TAE with technical success and were subsequently followed for a median of 636 (interquartile ranges 446-1292) days. The freedom from sac enlargement rates at 1, 3, and 5 years was 73.2%, 32.0%, and 26.7%, respectively. After initial TAE, the recurrent type II, delayed type I, and occult type III endoleak were identified in 39 (71%), 5 (9%), and 3 (5%) patients, respectively. Although a patient had aorto-duodenal fistula, there was no aneurysm-related death. The freedom from reintervention rates was 84.6%, 35.7%, and 17.0%, respectively. In the multivariate analysis, sac diameter > 55 mm at initial TAE (hazard ratios, 3.23; 95% confidence intervals, 1.22-8.58; P 55 mm at initial TAE was a significant predictor of sac enlargement