Off the wall: incidental paraspinal and pelvic muscle pathology on abdominopelvic imaging.

As the use of cross-sectional abdominal and pelvic imaging has increased exponentially in the past several decades, incidental musculoskeletal findings have become commonplace. These are often unrelated to the indication for the examination and are frequently referred to as the "radiologist's blind spot" on these studies. The differential diagnosis for abnormalities of the paraspinal and pelvic musculature is, in many cases, quite different from the anterior abdominal wall muscles. Furthermore, due to their relatively deep location, pathology involving the former muscle groups is more likely to be clinically occult, often presenting only incidentally when the patient undergoes cross-sectional imaging. Effective treatment of diseases of these muscles is dependent on adherence to a diverse set of diagnostic and treatment algorithms. The purpose of this review article is to familiarize the radiologist with the unique pathology of these often-overlooked muscles of the abdomen and pelvis.

Non-contrast and portal venous phase computed tomography in breast cancer hepatic metastases: comparison of tumor measurements and impact on response assessment.

BACKGROUND: For many common malignancies, including breast cancer, evaluation for metastatic disease using multiphase computed tomography (CT) has fallen out of favor and been replaced by studies performed only in the portal venous phase. However, differences in tumor vascularity could produce differences in appearance on post-contrast imaging. PURPOSE: To assess non-contrast phase and portal venous phase computed tomography in detection and measurement of hepatic metastases from breast carcinoma. MATERIALS AND METHODS: A total of 75 CT scans from 52 breast cancer patients were independently assessed by three body imagers for lesion presence, number and size. Readers randomly assessed portal venous phase or combined phase images at one session with cross-over reads performed four to six weeks later. RESULTS: In the 58% of cases where index lesions measured larger on combined phase, the mean difference in lesion size was 5.7 mm. In this group, combined phase reads demonstrated an 8.4 mm increase in sum of largest diameters, and a mean percentage sum of largest diameters increase of 19% compared to portal venous phase-only reads. CONCLUSION: Addition of non-contrast phase images results in increased index lesion size in most patients with hepatic metastases from breast cancer. If only the portal venous phase is utilized, there is potential for incorrectly diagnosing disease progression on follow-up due to underestimation of lesion size.

Combined Qualitative and Quantitative Assessment of Low-Attenuation Renal Lesions Improves Identification of Renal Malignancy on Noncontrast Computed Tomography.

OBJECTIVE: The objective of this study was to assess renal lesions measuring less than 20 Hounsfield units (HU) on noncontrast computed tomography (NCT). METHODS: Twenty-one (18.1%) of 116 consecutive pathologically proven renal cell carcinomas measured less than 20 HU on NCT and were compared with 40 confirmed benign cysts also measuring less than 20 HU. All lesions were assessed qualitatively (heterogeneous or homogenous) by 3 blinded readers and quantitatively with commercially available textural analysis software. Finally, a combined assessment was performed. RESULTS: Qualitative assessment performed well (sensitivity, 76%-90%; specificity, 70%-88%). Quantitative assessment revealed mean positive pixels as having the highest performance (area under the curve, 0.912; sensitivity, 90%; specificity, 80% at a cutoff value of 21). The combined assessment, using the mean positive pixel cutoff, improved the sensitivity (reader 1, 100%; reader 2, 95%; and reader 3, 95%). CONCLUSION: Qualitative and quantitative assessments have relatively good performance, but the combination can nearly eliminate renal cell carcinomas being missed on NCT.

Impact of low-kVp scan technique on oral contrast density at abdominopelvic CT.

PURPOSE: To assess quantitative and qualitative effects of kVp on oral contrast density. MATERIALS AND METHODS: Three readers retrospectively reviewed 100 CT scans performed at a range of high- and low-energy settings, independently determining their preferred window and level settings for evaluation of the oral-contrast-opacified bowel. Contrast density was also assessed quantitatively in the stomach, jejunum, and ileum. Subsequently, a range of oral contrast dilutions were imaged at varying kVp's in a commercially available CIRS tissue equivalent phantom model. RESULTS: In the retrospective patient study, mean oral contrast density increased significantly in the ileum compared to the jejunum (455.2 and 308.8 HU, respectively, p < 0.01). Similar findings were seen in patients regardless of patients' weight. Mean oral contrast density was higher on lower-energy scans, requiring more window/level adjustment. An oral contrast iodine concentration of 5.82-7.77 mg I/mL most closely approximated a target oral contrast density of 200 HU. CONCLUSIONS: Oral contrast density is strongly influenced by kVp, supporting use of more dilute oral contrast when using lower-kVp techniques.

Acute Appendicitis Involving a De Garengeot Hernia.

We present a case of appendicitis within a De Garengeot hernia. The patient presented to the emergency department with 4 days of worsening abdominal pain. Computed tomography examination revealed an inflamed appendix within a femoral hernia. The patient underwent appendectomy and repair of the femoral defect. Pathological examination was consistent with acute appendicitis. De Garengeot hernia is a rare phenomenon, with less than 5% of femoral hernias containing the appendix and 0.08% to 0.13% containing an incarcerated acute appendicitis.

Differentiating biliary cystadenomas from benign hepatic cysts: Preliminary analysis of new predictive imaging features.

OBJECTIVE: To identify performance of imaging features in differentiating hepatic cysts from biliary cystadenomas of the liver. METHODS: 25 pathologically confirmed hepatic cystic lesions (hepatic cysts or biliary cystadenomas) were evaluated retrospectively and predetermined imaging features assessed for performance in differentiation. RESULTS: Any septation which arose from a cyst wall without external indentation had a very high association with biliary cystadenoma, while the presence of a thick septation had only a moderate association. CONCLUSIONS: The relationship between septations and the wall of the cystic lesion performed better than previously reported features including thick septations.

Use of Low-Fidelity Simulation Laboratory Training for Teaching Radiology Residents CT-Guided Procedures.

PURPOSE: To determine the benefit of the addition of low-fidelity simulation-based training to the standard didactic-based training in teaching radiology residents common CT-guided procedures. METHODS: This was a prospective study involving 24 radiology residents across all years in a university program. All residents underwent standard didactic lecture followed by low-fidelity simulation-based training on three common CT-guided procedures: random liver biopsy, lung nodule biopsy, and drain placement. Baseline knowledge, confidence, and performance assessments were obtained after the didactic session and before the simulation training session. Approximately 2 months later, all residents participated in a simulation-based training session covering all three of these procedures. Knowledge, confidence, and performance data were obtained afterward. These assessments covered topics related to preprocedure workup, intraprocedure steps, and postprocedure management. Knowledge data were collected based on a 15-question assessment. Confidence data were obtained based on a 5-point Likert-like scale. Performance data were obtained based on successful completion of predefined critical steps. RESULTS: There was significant improvement in knowledge (P = .005), confidence (P < .008), and tested performance (P < .043) after the addition of simulation-based training to the standard didactic curriculum for all procedures. CONCLUSIONS: This study suggests that the addition of low-fidelity simulation-based training to a standard didactic-based curriculum is beneficial in improving resident knowledge, confidence, and tested performance of common CT-guided procedures.

Effect of Direct Marketing for Uterine Artery Embolization on Rates of Leiomyomas, Incidental Findings, and Management After Pelvic MRI.

PURPOSE: The aim of this study was to determine whether a self-referred population screened by an interventional radiology (IR) clinic and a non-IR, physician-referred population differed with regard to suitability for uterine artery embolization (UAE) for symptomatic leiomyomas on the basis of preprocedure MRI. METHODS: This was an institutional review board-approved, HIPAA-compliant retrospective study of 301 women evaluated in an IR clinic for possible UAE from January 2009 to September 2012. Subjects were retrospectively divided into two groups: self-referred via direct marketing (group A, n = 203; mean age, 41.8 years; range, 22-58 years) and physician referred (group B, n = 98; mean age, 42.9 years; range, 30-65 years). RESULTS: There was no significant difference between groups in presenting symptoms (multiple symptoms, bleeding, bulk-related symptoms, pain). After initial screening, 73.4% of group A (149 of 203) and 79.6% of group B (78 of 98) underwent MRI (P = .242). On the basis of MRI findings, 91.3% of group A (136 of 149) and 94.9% of group B (74 of 78) had uterine leiomyomas (P = .328). Adenomyosis without leiomyoma was present in 4.0% of group A (6 of 149) and 3.8% of group B (3 of 78) (P = .947). Incidental findings requiring further clinical or imaging evaluation were found in 20.8% of group A (31 of 149) and 24.4% of group B (19 of 78) (P = .539). After MRI, 41.6% of group A (62 of 149) and 48.7% of group B (38 of 78) proceeded to UAE (P = .306). CONCLUSIONS: After initial screening, similar proportions of self-referred and physician-referred patients were candidates for UAE. The rates of confirmed leiomyomas and incidental findings on MRI were similar between groups.

Optimization of window settings for virtual monoenergetic imaging in dual-energy CT of the liver: A multi-reader evaluation of standard monoenergetic and advanced imaged-based monoenergetic datasets.

OBJECTIVES: To evaluate optimal window settings for display of virtual monoenergetic reconstructions in third-generation dual-source, dual-energy computed tomography (DECT) of the liver. METHODS: Twenty-nine subjects were prospectively evaluated with DECT in arterial (AP) and portal venous (PVP) phases. Three reconstructed datasets were calculated: standard linearly-blended (LB120), 70-keV standard virtual monoenergetic (M70), and 50-keV advanced image-based virtual monoenergetic (M50+). Two readers assessed optimal window settings (width and level, W/L), establishing a mean for each reconstruction which was used for a blinded assessment of liver lesions. RESULTS: The optimal W/L for M50+ were significantly higher for both AP (W=429.3 ± 44.6 HU, L=129.4 ± 9.7 HU) and PVP (W=376.1 ± 14.2HU, L=146.6 ± 7.0 HU) than for LB120 (AP, W=215.9 ± 16.9 HU, L=82.3 ± 9.4 HU) (PVP, W=173.4 ± 8.9 HU, L=69.3 ± 6.0 HU) and M70 (AP, W=247.1 ± 22.2 HU, L=72.9 ± 6.8 HU) (PVP, W=232.0 ± 27.9 HU, L=91.6 ± 14.4 HU). Use of the optimal window setting for M50+ vs. LB120 resulted in higher sensitivity (AP, 100% vs. 86%; PVP, 96% vs. 63%). CONCLUSIONS: Application of dedicated window settings results in improved liver lesion detection rates in advanced image-based virtual monoenergetic DECT when customized for arterial and portal venous phases.

Application of an Advanced Image-Based Virtual Monoenergetic Reconstruction of Dual Source Dual-Energy CT Data at Low keV Increases Image Quality for Routine Pancreas Imaging.

PURPOSE: To compare image quality on contrast-enhanced dual-energy computed tomography (DECT) during the pancreatic parenchymal phase of pancreatic masses between linearly-blended simulated 120 kVp images (routine) and advanced image-based virtual monoenergetic reconstructions at 55 keV. METHODS: This was a retrospective evaluation of 24 nonconsecutive adults found to have a focal pancreatic mass on a multiphasic abdominal dual-source DECT (12 adenocarcinoma, 5 neuroendocrine, 7 cystic tumors). For pancreatic-parenchymal phase images, subjects had routine and 55 keV images reconstructed at the time of clinical evaluation. Quantitative evaluation by contrast-to-noise ratio and qualitative evaluations of image quality by (1) direct comparison of image pairs (preference) and (2) blinded assessment of image quality measures based on Likert scores were performed. RESULTS: Mean patient weight was 205.8 ± 26.6 lbs. Mean pancreatic lesion contrast-to-noise ratio was significantly higher at 55 keV (6.8 ± 4.1) compared to the routine image series (5.8 ± 3.8; P = 0.0002). All 3 readers preferred the 55-keV images over routine blended images in 70.1% to 95.8% of cases. No significant differences were observed for subjective sharpness of the mass, visualization of internal mass structures, or image noise. CONCLUSIONS: Use of a single advanced image-based virtual monoenergetic reconstruction at 55 keV in pancreatic DECT showed improved objective image quality and reader preference compared to routine images. As this image reconstruction can be incorporated into the scan protocol, this technique should be considered for routine clinical use.

Comparison of High-Fidelity Simulation Versus Didactic Instruction as a Reinforcement Intervention in a Comprehensive Curriculum for Radiology Trainees in Learning Contrast Reaction Management: Does It Matter How We Refresh?

RATIONALE AND OBJECTIVES: Simulation-based training has been shown to be a useful adjunct to standard didactic lecture in teaching residents appropriate management of adverse contrast reactions. In addition, it has been suggested that a biannual refresher is needed; however, the type of refresher education has not been assessed. MATERIALS AND METHODS: This was a prospective study involving 31 radiology residents across all years in a university program. All residents underwent standard didactic lecture followed by high-fidelity simulation-based training. At approximately 6 months, residents were randomized into a didactic versus simulation group for a refresher. At approximately 9 months, all residents returned to the simulation center for performance testing. Knowledge and confidence assessments were obtained from all participants before and after each phase. Performance testing was obtained at each simulation session and scored based on predefined critical actions. RESULTS: There was significant improvement in knowledge (P < .002) and confidence (P < .001) after baseline education of combined didactic and simulation-based training. There was no statistical difference between the simulation and didactic groups in knowledge or confidence at any phase of the study. There was no significant difference in tested performance between the groups in either performance testing session. CONCLUSIONS: This study suggests that a curriculum consisting of an annual didactic lecture combined with simulation-based training followed by a didactic refresher at 6 months is an effective and efficient (both cost-effective and time-effective) method of educating radiology residents in the management of adverse contrast reactions.

Increased renal cyst density on abdominal CT at 100-kVp compared with 120-kVp: a preliminary evaluation.

OBJECTIVE: To compare the radiographic density of renal cysts on contrast-enhanced computed tomography (CT) scans performed at tube voltages of 100 versus 120 kVp. METHODS: Thirty-six renal cysts from contrast-enhanced CT performed on 21 subjects at both 120 kVp and 100 kVp were compared by Kolmogorov-Smirnov statistical testing. RESULTS: The radiographic density (mean+/-standard deviation in Hounsfield units) of cysts was greater on 100-kVp than on 120-kVp CT scans for both 5-mm and 2-mm reconstructed slice thicknesses: 16.6+/-5.6 versus 10.9+/-4.9 and 14.1+/-5.6 versus 8.5+/-3.9, respectively. CONCLUSIONS: Decrease in tube voltage significantly increases measured radiographic density of renal cysts on CT. Further studies are indicated to assess the clinical impact of lower-tube-voltage CT.

Renal metastasis of an ovarian granulosa cell tumour inducing growth of a cystic nephroma.

A 44-year-old woman presented with a large pelvic mass. Pathology revealed a granulosa cell tumour of the left ovary. The patient was followed after surgery with inhibin B levels and interval imaging. Six years later, she began to experience severe back pain. A vertebral biopsy was positive for metastatic granulosa cell tumour. She underwent radiation to the spine. Inhibin B levels began to rise and, several months later, a CT scan showed a large heterogeneous mass essentially replacing the left kidney. She underwent an open left radical nephrectomy. Pathology revealed a 12 cm cystic nephroma with a 5 cm nodule of metastatic granulosa cell tumour. Immunohistochemistry demonstrated that the mass was inhibin and oestrogen receptor positive. This is a novel presentation of these coexisting pathologies. This unique case sheds light on the possibility of induction of cystic nephroma by the altered hormonal environment created by a granulosa cell tumour metastasis.