Christian B. van der Pol

Diagnosis of Sarcomatoid Renal Cell Carcinoma With CT: Evaluation by Qualitative Imaging Features and Texture Analysis.

OBJECTIVE The objective of our study was to determine whether CT findings, including texture analysis, can differentiate sarcomatoid renal cell carcinoma (RCC) from clear cell RCC. MATERIALS AND METHODS A retrospective case-control study was performed of consecutive patients with a histologic diagnosis of sarcomatoid RCC (n = 20) and clear cell RCC (n = 25) who underwent preoperative CT over a 3-year period. The CT images were independently reviewed by two blinded abdominal radiologists; they evaluated the following: tumor heterogeneity, tumor margin, calcification, intratumoral neovascularity, peritumoral neovascularity, renal sinus invasion, renal vein invasion, and adjacent organ invasion. Interobserver agreement was assessed using the Cohen kappa coefficient, and results were compared between groups using an independent Student t test and the chi-square test with a Bonferroni correction. For texture analysis, gray-level co-occurrence and run-length matrix features were extracted and compared using Mann-Whitney U tests. ROC curves for each tumor were constructed, and AUCs were calculated. RESULTS Overall, sarcomatoid RCCs were larger than clear cell RCCs, measuring 77 ± 27 mm (mean ± SD) compared with 50 ± 29 mm (p = 0.003), respectively; however, there was no difference in tumor size between the tumors that were compared using texture analysis or subjective analysis (p = 0.06 and 0.03, respectively). From the subjective analysis, only peritumoral neovascularity (readers 1 and 2: 70% and 70% sarcomatoid RCCs vs 0% and 41.6% clear cell RCCs, respectively; p = 0.001) and the size of the peritumoral vessels (p < 0.001) differed between sarcomatoid RCCs and clear cell RCCs, and interobserver agreement was fair (κ = 0.38). Other subjective imaging features did not differ between the tumors (p > 0.005). There was greater run-length nonuniformity and greater gray-level nonuniformity in sarcomatoid RCCs than in clear cell RCCs (p = 0.03 and p = 0.04, respectively). The combined textural features identified sarcomatoid RCC with an AUC of 0.81 ± 0.08 (standard error) (p < 0.0001). CONCLUSION Large tumor size, the presence of peritumoral neovascularity, and larger peritumoral vessels are features that are more commonly associated with sarcomatoid RCCs than with clear cell RCCs. Sarcomatoid RCCs are also more heterogeneous by texture analysis than clear cell RCCs.

Is Quality and Completeness of Reporting of Systematic Reviews and Meta-Analyses Published in High Impact Radiology Journals Associated with Citation Rates?

Purpose The purpose of this study is to determine whether study quality and completeness of reporting of systematic reviews (SR) and meta-analyses (MA) published in high impact factor (IF) radiology journals is associated with citation rates. Methods All SR and MA published in English between Jan 2007–Dec 2011, in radiology journals with an IF >2.75, were identified on Ovid MEDLINE. The Assessing the Methodologic Quality of Systematic Reviews (AMSTAR) checklist for study quality, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist for study completeness, was applied to each SR & MA. Each SR & MA was then searched in Google Scholar to yield a citation rate. Spearman correlation coefficients were used to assess the relationship between AMSTAR and PRISMA results with citation rate. Multivariate analyses were performed to account for the effect of journal IF and journal 5-year IF on correlation with citation rate. Values were reported as medians with interquartile range (IQR) provided. Results 129 studies from 11 journals were included (50 SR and 79 MA). Median AMSTAR result was 8.0/11 (IQR: 5–9) and median PRISMA result was 23.0/27 (IQR: 21–25). The median citation rate for SR & MA was 0.73 citations/month post-publication (IQR: 0.40–1.17). There was a positive correlation between both AMSTAR and PRISMA results and SR & MA citation rate; ρ=0.323 (P=0.0002) and ρ=0.327 (P=0.0002) respectively. Positive correlation persisted for AMSTAR and PRISMA results after journal IF was partialed out; ρ=0.243 (P=0.006) and ρ=0.256 (P=0.004), and after journal 5-year IF was partialed out; ρ=0.235 (P=0.008) and ρ=0.243 (P=0.006) respectively. Conclusion There is a positive correlation between the quality and the completeness of a reported SR or MA with citation rate which persists when adjusted for journal IF and journal 5-year IF.

Imaging Anatomy and Pathology of Extraocular Muscles in Adults

The extraocular muscles (EOM) are involved in a variety of disease processes with characteristic findings on imaging. EOM anatomy is described, followed by a review of adult EOM pathology. The imaging characteristics are explained with examples. The pattern of EOM disease on imaging, in corroboration with clinical findings, can often lead the radiologist towards a specific diagnosis.

Intracellular lipid in clear cell renal cell carcinoma tumor thrombus and metastases detected by chemical shift (in and opposed phase) MRI: radiologic-pathologic correlation.

Background Clear cell renal cell carcinoma (RRC) characteristically contain intracellular lipid which is also detectable in tumor thrombus and metastases. Purpose To assess the incidence of intracellular lipid in clear cell RCC metastases and tumor thrombus using chemical shift MRI. Material and Methods With REB approval, 33 consecutive patients with clear cell RCC and tumor thrombus/metastatic disease underwent magnetic resonance imaging (MRI) over a 10-year period. Diagnosis was established by histopathology for tumor thrombi (n = 25) and metastases (n = 15) or growth for metastases (n = 14). Two blinded radiologists independently assessed for a signal intensity (SI) drop at chemical shift MRI (indicative of intracellular lipid) and a third radiologist established consensus. Chemical shift SI (CS-SI) index ([SItumorIP – SItumorOP]/SITumorIP x 100) was calculated. Inter-observer agreement was assessed using intra-class correlation (ICC) and tests of association were performed using the Chi-square test and Spearman correlation. Results Using CS-MRI, intracellular lipid was detected in 36.4% of clear cell RCC, with moderate agreement, (ICC = 0.5). Intracellular lipid was detected in 20% of tumor thrombi and 20% of metastases with strong agreement (ICC = 0.73). Intracellular lipid within tumor thrombi/metastases was not associated with lipid within the primary tumor (P = 0.09). There was a correlation in CS-SI index between primary tumor and thrombi/metastases when lipid was detected in both lesions (r = 0.91, P = 0.005); however, there was no correlation when lipid was not detected in both lesions (r = –0.09, P = 0.72). Conclusion The presence of intracellular lipid in tumor thrombus and metastases from clear cell RCC is uncommon and, is not necessarily associated with lipid within the primary tumor at chemical shift MRI.

High-resolution T2-weighted (T2W) oblique plane turbo spin-echo (TSE) MRI for rectal adenocarcinoma staging

PURPOSE The purpose of this study was to determine the frequency/significance of incorrectly planned oblique T2-weighted (T2W) MRI of rectal adenocarcinoma. METHODS Eighty-six consecutive patients underwent MRI for rectal cancer staging. Two radiologists evaluated oblique T2W imaging and tumor stage. RESULTS A total of 71% of middle/high tumors had correctly planned oblique T2W-MRI. Thirteen of 14 low tumors (N=7) or tumors spanning at least two rectal segments (N=7) had incorrectly planned oblique T2W-MRI. The sensitivity/specificity of staging on correct compared to incorrect oblique T2W was: 88.9/50% (R1)/77.8/60% (R2) and 80/100% (R1)/60/80% (R2), (P=.54). Agreement was substantial, K=0.67. CONCLUSIONS Oblique T2W-MRI is incorrectly performed in low tumors and those spanning multiple rectal segments. In this study, planning errors did not impact staging accuracy.