Intraductal carcinoma of the prostate (IDC-P) lowers apparent diffusion coefficient (ADC) values among intermediate risk prostate cancers.

BACKGROUND: Prostatic intraductal carcinoma (IDC-P) is an aggressive variant of prostate cancer (PCa) characterized by proliferation of malignant cells within prostatic ducts/acini and nucleomegaly. PURPOSE/HYPOTHESIS: To compare apparent diffusion coefficient (ADC) values and Prostate Imaging and Data Reporting System (PI-RADS) v. 2 scores in intermediate risk (International Society of Urological Pathology [ISUP] Grade Group [GG] 2 and 3) PCa with/without IDC-P to determine if IDC-P alters the MRI appearance of PCa. STUDY TYPE: Retrospective, case-control. POPULATION: Fifteen consecutive men with ISUP GG 2/3 (Gleason score 3+4 = 7 [N = 4], 4+3 = 7 [N = 11]) PCa with IDC-P diagnosed at radical prostatectomy were compared with: 1) ISUP GG 2/3 PCa without IDC-P (matched for percentage Gleason pattern 4), and 2) ISUP GG 4 and 5 (Gleason score 8/9) PCa without IDC-P. FIELD STRENGTH/SEQUENCE: 3T multiparametric MRI. ASSESSMENT: Two blinded radiologists (R1/R2) measured mean ADC, ADC.ratio (ADC.tumor/ADC.normal peripheral zone) and assigned PI-RADS v2 scores. Statistical Tests: Chi-square and analysis of variance (ANOVA). RESULTS: There were no differences in age, prostate serum antigen, tumor size, or stage between groups (P = 0.063-0.912). Tumors with IDC-P had lower mean ADC and ADC.ratio (0.741 ± 0.152 mm2 /sec and 0.44 ± 0.07) compared with ISUP GG 2/3 tumors without IDC-P (0.888 ± 0.167 mm2 /sec and 0.62 ± 0.14), P = 0.012 and <0.001; and did not differ compared with ISUP GG 4/5 tumors (0.705 ± 0.141 mm2 /sec and 0.44 ± 0.08), P = 0.509 and 0.868. Tumors with IDC-P were nearly all PI-RADS v2 score 5 (14/15) compared with ISUP GG 2/3 tumors without IDC-P (10/15 R1, 8/15 R2) and GG 4/5 tumors (9/15), (P = 0.040 = 0.092). Agreement in PI-RADS v2 scoring was moderate (K = 0.68). DATA CONCLUSION: ISUP GG 2 and 3 (intermediate risk, Gleason score 7) PCa with IDC-P have lower ADC compared with tumors without IDC-P with a similar percentage of Gleason pattern 4 and resemble ISUP GG 4 and 5 high risk tumors on MRI. IDC-P lowers ADC values among intermediate risk prostate cancers. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:279-287.

Evaluation of a free-breathing respiratory-triggered (Navigator) 3-D T1-weighted (T1W) gradient recalled echo sequence (LAVA) for detection of enhancement in cystic and solid renal masses.

OBJECTIVES: To evaluate free-breathing Navigator-triggered 3-D T1-weighted MRI (NAV-LAVA) compared to breath-hold (BH)-LAVA among cystic and solid renal masses. MATERIALS AND METHODS: With an IRB waiver, 44 patients with 105 renal masses (71 non-enhancing cysts and 14 cystic and 20 solid renal masses) underwent MRI between 2016 and 2017 where BH-LAVA and NAV-LAVA were performed. Subtraction images were generated for BH-LAVA and NAV-LAVA using pre- and 3-min post-gadolinium-enhanced images and were evaluated by two blinded radiologists for overall image quality, image sharpness, motion artifact, and quality of subtraction (using 5-point Likert scales) and presence/absence of enhancement. Percentage signal intensity change (Δ%SI) = ([SI.post-gadolinium-SI.pre-gadolinium]/SI.pre-gadolinium)*100, was measured on BH-LAVA and NAV-LAVA. Likert scores were compared using Wilcoxon's sign-rank test and accuracy for detection of enhancement compared using receiver operator characteristic (ROC) analysis. RESULTS: Overall image quality (p = 0.002-0.141), image sharpness (p = 0.002-0.031), and motion artifact were better (p = 0.002) comparing BH-LAVA to NAV-LAVA for both radiologists; however, quality of image subtraction did not differ between groups (p = 0.09-0.14). Sensitivity/specificity/area under ROC curve for enhancement in cystic and solid renal masses using subtraction and %SIΔ were (1) BH-LAVA: 64.7%/98.6%/0.82 (radiologist 1), 61.8%/95.8%/0.79 (radiologist 2), and 70.6%/81.7%/0.76 (%SIΔ) versus 2) NAV-LAVA: 58.8%/95.8%/0.79 (radiologist 1, p = 0.16), 58.8%/88.7%/0.73 (radiologist 2, p = 0.37), and 73.5%/76.1%/0.75 (%SIΔ, p = 0.74). CONCLUSIONS: NAV-LAVA showed similar quality of subtraction and ability to detect enhancement compared to BH-LAVA in renal masses albeit with lower image quality, image sharpness, and increased motion artifact. NAV-LAVA may be considered in renal MRI for patients where BH is suboptimal. KEY POINTS: • Free-breathing Navigator (NAV) 3-D subtraction MRI is comparable to breath-hold (BH) images. • Accuracy for subjective and quantitative diagnosis of enhancement in renal masses on NAV 3-D T1W is comparable to BH MRI. • NAV 3-D T1W renal MRI is useful in patients who may not be able to adequately BH.

Benign Posttraumatic Pseudopneumoperitoneum.

OBJECTIVE: The objective of our study was to retrospectively determine the anatomic distribution of chest wall ectopic gas resembling pneumoperitoneum (i.e., pseudopneumoperitoneum) and its relationship with trauma mechanisms and clinical outcomes using CT. MATERIALS AND METHODS: Investigators from two separate trauma referral centers screened 492 chest, abdomen, and pelvis CT examinations of patients who had sustained any form of trauma between 2010 and 2015. After excluding 186 patients with recognized causes of ectopic gas, 306 patients (211 men and 95 women; mean age, 44.5 years; range, 6-95 years) remained for analysis by two radiology residents in center 1 and a radiology resident in center 2. Positive cases were reviewed by all investigators, including an experienced fellowship-trained abdominal radiologist. The anatomic location of the pseudopneumoperitoneum, injury severity score, trauma velocity (high speed vs low or unknown speed), trauma mechanism, clinical findings on follow-up, and exploratory laparotomy data were collected for patients with pseudopneumoperitoneum. Two hundred consecutive nontrauma CT examinations from 2015 were selected as control cases by a resident in center 1. The t test and chi-square test were used for determining associations. RESULTS: Pseudopneumoperitoneum was identified in 5.2% of patients, occurring bilaterally adjacent to the lower six costochondral junctions, and was significantly more common with high-velocity trauma than with low-velocity trauma (p = 0.010). None of the patients with pseudopneumoperitoneum had evidence of perforated hollow viscus at surgery (n = 2) or on clinical follow-up (n = 14). No patients had unnecessary surgery due to pseudopneumoperitoneum. CONCLUSION: Pseudopneumoperitoneum is a posttraumatic phenomenon centered near the lower six costochondral junctions. Recognizing these findings may help prevent unnecessary laparotomy in the trauma setting.

Revisiting the surface anatomy of the sciatic nerve in the gluteal region.

The surface anatomy of the sciatic nerve (SN) in the gluteal region is clinically important (e.g., intramuscular injection). Anatomy texts describe the nerve in relation to the posterior superior iliac spine (PSIS), ischial tuberosity (IT), and greater trochanter (GT) but descriptions are inconsistent. The surface anatomy of the SN was determined in relation to these bony landmarks using computed tomography (CT) scans in living adults. One hundred consecutive adult pelvic CT scans (36 females, mean age 76 years) were available for dual consensus analysis. A further 19 adults (9 females, mean age 74 years) underwent pelvic CT scans in both prone and supine positions. The surface projection of the SN along a line between the PSIS and IT and between the IT and GT was measured. The SN was identified in 95% of scans at a mean of 5.2 ± 1.0 cm from the PSIS and 11.4 ± 1.1 cm from the IT. The SN was a mean of 5.8 ± 0.8 cm from the IT and 6.2 ± 1.0 cm from the GT. There were no significant differences in mean positions of the nerve between sides and sexes. A small but clinically irrelevant difference in the surface marking of the SN was found between supine and prone positions with respect to the GT and IT but not in relation to the PSIS and IT. In living adults, the SN lies approximately one-third of the way along a line between the PSIS and IT and half way between the GT and IT.