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PurposeTo analyze changes in MRI diagnostic accuracy in main rectal tumor (T) evaluation resulting from the use of diffusion-weighted imaging (DWI), according to the degree of experience of the radiologist.
MethodsThis is a cross-sectional study of a database including one hundred 1.5 T MRI records (2011–2016) from patients with biopsy-proven rectal cancer, including primary staging and post-chemoradiotherapy follow-up. All cases were individually blindedly reviewed by ten radiologists: three experienced in rectal cancer, three specialized in other areas, and four residents. Each case was assessed twice to detect perirectal infiltration: first, evaluating just high-resolution T2-weighted sequences (HRT2w); second, evaluation of DWI plus HRT2w sequences. Results were pooled by experience, calculating accuracy (area under ROC curve), sensitivity and specificity, predictive values, likelihood ratios, and overstaging/understaging. Histology of surgical specimens provided the reference standard.
ResultsDWI significantly improved specificity by experienced radiologists in primary staging (63.2% to 75.9%) and, to a lesser extent, positive likelihood ratio (2.06 to 2.87); minimal changes were observed post-chemoradiotherapy, with a slight decrease of accuracy (0.657 to 0.626). Inexperienced radiologists showed a similar pattern, but with slight enhancement post-chemoradiotherapy (accuracy 0.604 to 0.621). Residents experienced small changes, with increased sensitivity/decreased specificity in both primary (69% to 72%/67.2% to 64.7%) and post-chemoradiotherapy (68.1% to 73.6%/47.3% to 44.6%) staging.
ConclusionsAdding DWI to HRT2w significantly improved specificity for the detection of perirectal infiltration at primary staging by experienced radiologists and also by inexperienced ones, although to a lesser extent. In the post-neoadjuvant treatment subgroup, only minimal changes were observed.
PurposeTo compare the cross-sectional imaging findings of immunoglobulin G4-related sclerosing cholangiopathy (IgG4-SC) and cholangiocarcinoma (CCA).
MethodsRetrospective search of radiology and pathology databases identified 24 patients with IgG4-SC and over 500 patients with CCA from January 2009 to December 2016. Patients with no pre-treatment imaging studies available on PACS, non-contrasted imaging only, presence of mass lesions, metastatic disease or biliary stents were excluded. 17 patients with IgG4-SC and a selected group of 20 (age and gender matched) patients with CCA were obtained. Images were blinded and independently reviewed by two radiologists. Differences in proportions and means between groups were analyzed using Fishers and Mann–Whitney tests, respectively.
ResultsBoth readers identified a statistically significant difference in the presence of abrupt common bile duct narrowing between IgG4-SC and CCA (6.7% vs. 68.4%, p < 0.001; 33.3% vs. 75%, p = 0.019). No difference was seen in biliary wall thickening, wall enhancement, extrahepatic exclusive location of disease, or pancreatic duct dilation. Inter-observer variability was κ = 0.52. Total bilirubin and CA 19-9 were unable to differentiate between IgG4-SC and CCA. Serum IgG4 was positive in two of six IgG4-SC patients who were tested.
ConclusionIgG4-SC and CCA share many clinical and imaging findings on CT and MRI. Abrupt bile duct cut sign strongly favors CCA. In the absence of this finding, IgG4-SC should be considered in the differential diagnosis in all cases of suspected extrahepatic CCA.
PurposeTo investigate the association between metabolic parameters of dual time point 18F-FDG PET/CT imaging and Kirsten rat sarcoma (KRAS) mutation status in colorectal liver metastases (CRLM).
MethodsForty-nine colorectal cancer patients with 87 liver metastatic lesions were included in this retrospective study. KRAS gene mutation tests were also performed for all the patients. The maximum standardized uptake value (SUVmax) was measured for each hepatic metastatic lesion on both early and delayed scans, and the change of SUVmax (ΔSUVmax) and retention index (RI) were calculated. Uni-variate and multi-variate analyses were employed to determine the relationship between any PET/CT parameters and KRAS mutation status.
ResultsThirty-seven (42.5%) liver metastatic lesions harboring KRAS mutations were identified. The SUVmax of CRLM with KRAS mutation both on early and delayed scans was significantly higher than those with wild-type KRAS (10.7 ± 6.0 vs. 7.8 ± 3.3, P = 0.002; 15.5 ± 10.1 vs. 10.0 ± 4.2, P < 0.001, respectively). Compared with wild-type KRAS CRLM, ΔSUVmax and RI (%) of CRLM with KRAS mutation were also significantly higher than those with wild-type KRAS (4.8 ± 4.7 vs. 2.2 ± 2.0, P < 0.001; 45.3 ± 28.2 vs. 29.6 ± 24.7, P = 0.003, respectively). Multi-variate analyses showed that the SUVmax on both early and delayed scans, ΔSUVmax, and RI (%) were the 4 independent factors to predict CRLM patients harboring KRAS mutations.
ConclusionThe SUVmax on both early and delayed scans, ΔSUVmax, and RI (%) may be the 4 independent factors to predict CRLM patients harboring KRAS mutations.
PurposeBody composition is of great prognostic value in several severe diseases, including different types of cancer as well as cardiometabolic disorders. We aimed to investigate the correlations of skeletal muscle mass and abdominal adipose tissue compartments between volumetric and single-slice measurements to study the usefulness of several anatomical landmarks for estimation of total compartment volumes using abdominal CT-scans.
MethodsIn this retrospective study volumetric quantifications of paraspinal skeletal muscles (SM) and adipose tissue compartments (visceral adipose tissue, VAT; subcutaneous adipose tissue, SAT) were performed in 50 consecutive patients (26 male; mean age, 63 ± 15 years) who underwent abdominal multislice-CT for diagnostic purposes using an in-house software. Associations between total volumes of SM, VAT, and SAT with single-slice measurements at eight predefined anatomical landmarks (median intervertebral disk spaces T12/L1 to L5/S1; level of the umbilicus (U); level of the radix of the superior mesenteric artery (SMA)) were studied using correlation coefficients.
ResultsStatistical analysis revealed a strong association between single-slice measurements of adipose tissue compartments with total VAT and SAT volume (VAT: all r > 0.89, P < 0.001; SAT: all r > 0.95, P < 0.001). The strongest associations with total SM volume were found for single-slice measurements obtained at L3/4 (r = 0.94, P < 0.001) and were further improved by normalization to height (r = 0.98, P < 0.001).
ConclusionsSingle-slice measurements of SM, VAT, and SAT at several anatomical landmarks are strongly associated with total compartment volumes and therefore allow for easy and simultaneous assessment of skeletal muscle mass and adipose tissue compartment volumes.
PurposeCorrected T1 (cT1) value is a novel MRI-based quantitative metric for assessing a composite of liver inflammation and fibrosis. It has been shown to distinguish between non-alcoholic fatty liver disease (NAFL) and non-alcoholic steatohepatitis. However, these studies were conducted in patients at high risk for liver disease. This study establishes the normal reference range of cT1 values for a large UK population, and assesses interactions of age and gender.
MethodsMR data were acquired on a 1.5 T system as part of the UK Biobank Imaging Enhancement study. Measures for Proton Density Fat Fraction and cT1 were calculated from the MRI data using a multiparametric MRI software application. Data that did not meet quality criteria were excluded from further analysis. Inter and intra-reader variability was estimated in a set of data. A cohort at low risk for NAFL was identified by excluding individuals with BMI ≥ 25 kg/m2 and PDFF ≥ 5%. Of the 2816 participants with data of suitable quality, 1037 (37%) were classified as at low risk.
ResultsThe cT1 values in the low-risk population ranged from 573 to 852 ms with a median of 666 ms and interquartile range from 643 to 694 ms. Iron correction of T1 was necessary in 36.5% of this reference population. Age and gender had minimal effect on cT1 values.
ConclusionThe majority of cT1 values are tightly clustered in a population at low risk for NAFL, suggesting it has the potential to serve as a new quantitative imaging biomarker for studies of liver health and disease.
IntroductionThe hepatoduodenal ligament is frequently involved by conditions affecting the portal triad and surrounding structures, including a vast array of non-neoplastic conditions. Due its unique location between the retroperitoneum and the peritoneal space, the hepatoduodenal ligament is also targeted by inflammatory conditions involving the retroperitoneum and the liver. Finally, the presence of lymphatics and of the biliary tracts makes the hepatoduodenal ligament a route of spread for a variety of infections. The purpose of this pictorial essay is twofold: to review the cross-sectional radiological anatomy and variants of the structures within the hepatoduodenal ligament, and to illustrate the non-neoplastic conditions that may arise within the hepatoduodenal ligament.
ConclusionFamiliarity with these specific entities and their cross-sectional imaging findings is fundamental for a more accurate diagnosis.
ObjectiveWhile the typical imaging features of the more common RCC subtypes have previously been described, they can at times have unusual, but distinguishing features. Rarer renal tumors span a broad range of imaging features, but they may also have characteristic presentations. We review the key imaging features of atypical presentations of malignant renal tumors and uncommon malignant renal tumors.
ConclusionRenal tumors have many different presentation patterns, but knowledge of the distinguishing MR and CT features can help identify both atypical presentation of common malignancies and uncommon renal tumors.
ObjectiveTo evaluate the feasibility of using PET/CT and diffusion-weighted magnetic resonance imaging (DW-MRI) to monitor the early response of pancreatic ductal adenocarcinoma (PDAC) xenografts to brachytherapy, and to determine whether maximum standardized uptake value (SUVmax) correlate with apparent diffusion coefficient (ADC).
Materials and MethodsSW1990 human PDAC were subcutaneously implanted in 20 nude mice. They were randomly divided into 125-Iodine (125I) seeds and blank seeds group. PET/CT and DW-MRI were performed at pretreatment and 5 days after therapy. SUVmax and ADC values were calculated, respectively. The correlation between SUVmax and ADC values was analyzed by the Pearson correlation test.
ResultsThe SUVmax were significantly decreased between pretreatment and 5 days after 125I seeds treatment (p < 0.001) and between two groups (p < 0.001). And the ADC values were significantly increased between pretreatment and 5 days after 125I seeds treatment (p < 0.001) and between two groups (p < 0.001). While in the bank seeds group, there were no significantly difference between pretreatment and after treatment in SUVmax and ADC values (p = 0.057; p = 0.397). SUVmax and ADC correlated significantly and negatively before treatment in both groups (r = − 0.964, R2 = 0.929, p < 0.001; r = − 0.917, R2 = 0.841, p < 0.001) and after treatment in the blank seeds group (r = − 0.944, R2 = 0.891, p < 0.001). But after 125I seeds treatment there was no significant correlation between SUVmax and ADC (r = − 0.388, R2 = 0.151, p = 0.268).
ConclusionThe PET/CT and DW-MRI are capable of monitoring the early response of PDAC xenografts to brachytherapy. The significantly inverse correlation between pretreatment SUVmax and ADC suggests that PET/CT and DW-MRI might play complementary roles for therapy assessment.