Alexander Brook

Spectral CT with Metal Artifacts Reduction Software for Improvement of Tumor Visibility in the Vicinity of Gold Fiducial Markers

PURPOSE To evaluate spectral computed tomography (CT) with metal artifacts reduction software (MARS) for reduction of metal artifacts associated with gold fiducial seeds. MATERIALS AND METHODS Thirteen consecutive patients with 37 fiducial seeds implanted for radiation therapy of abdominal lesions were included in this HIPAA-compliant, institutional review board-approved prospective study. Six patients were women (46%) and seven were men (54%). The mean age was 61.1 years (median, 58 years; range, 29-78 years). Spectral imaging was used for arterial phase CT. Images were reconstructed with and without MARS in axial, coronal, and sagittal planes. Two radiologists independently reviewed reconstructions and selected the best image, graded the visibility of the tumor, and assessed the amount of artifacts in all planes. A linear-weighted κ statistic and Wilcoxon signed-rank test were used to assess interobserver variability. Histogram analysis with the Kolmogorov-Smirnov test was used for objective evaluation of artifacts reduction. RESULTS Fiducial seeds were placed in pancreas (n = 5), liver (n = 7), periportal lymph nodes (n = 1), and gallbladder bed (n = 1). MARS-reconstructed images received a better grade than those with standard reconstruction in 60% and 65% of patients by the first and second radiologist, respectively. Tumor visibility was graded higher with standard versus MARS reconstruction (grade, 3.7 ± 1.0 vs 2.8 ± 1.1; P = .001). Reduction of blooming was noted on MARS-reconstructed images (P = .01). Amount of artifacts, for both any and near field, was significantly smaller on sagittal and coronal MARS-reconstructed images than on standard reconstructions (P < .001 for all comparisons). Far-field artifacts were more prominent on axial MARS-reconstructed images than on standard reconstructions (P < .01). Linear-weighted κ statistic showed moderate to perfect agreement between radiologists. CT number distribution was narrower with MARS than with standard reconstruction in 35 of 37 patients (P < .001). CONCLUSION Spectral CT with use of MARS improved tumor visibility in the vicinity of gold fiducial seeds.

Split-bolus spectral multidetector CT of the pancreas: assessment of radiation dose and tumor conspicuity.

PURPOSE To assess tumor conspicuity and radiation dose with a new multidetector computed tomography (CT) protocol for pancreatic imaging that combines spectral CT and split-bolus injection. MATERIALS AND METHODS This study was approved by the institutional review board and compliant with HIPAA. The requirement for informed consent was waived. One hundred sixty-three consecutive patients referred for possible pancreatic mass underwent CT with either a standard or split-bolus spectral CT protocol depending on scanner availability. Split-bolus spectral CT (CT unit with spectral imaging) combines pancreatic and portal venous phases in a single scan: 70 seconds before CT, 100 mL of contrast material is injected for the portal venous phase followed approximately 35 seconds later by injection of 40 mL of contrast material to boost the pancreatic phase. Bolus tracking after the second bolus initiates scanning 15 seconds after aorta enhancement reaches 280 HU. Images were reconstructed at 60 and 77 keV. The standard protocol (64-detector row unit) included unenhanced and pancreatic and portal venous phase imaging, with a single contrast material injection timed with bolus tracking 15 seconds after aortic enhancement of 300 HU for the pancreatic phase and 32 seconds later for the portal venous phase. Tumor conspicuity (difference in attenuation between tumor and pancreatic parenchyma) and contrast-to-noise ratio (CNR) were determined. Attenuation of aorta, main portal vein, and liver were measured. Patient size and per-examination radiation dose were recorded. The heteroscedastic t test, Fisher exact test, and Mann-Whitney test were used for statistical analysis. RESULTS There were no significant differences in age, weight, and body mass index between patients in the standard CT (46 of 80 patients had lesions) and split-bolus spectral CT (39 of 83 patients had lesions) groups; however, there were significantly more women in the split-bolus group (P = .02). Tumor conspicuity and CNR were higher with the 60-keV split-bolus protocol (89.1 HU ± 56.6 and 8.8 ± 6.2, respectively) than with the pancreatic or portal venous phase of the standard protocol (43.5 HU ± 28.4 and 4.5 ± 3.0, and 51.5 HU ± 30.3 and 5.6 ± 4.0, respectively; P < .01 for all comparisons). Dose-length product was 1112 mGy · cm ± 437 with the standard protocol and 633 mGy · cm ± 105 with the split-bolus protocol (P < .001). CONCLUSION Split-bolus spectral multidetector CT resulted in vascular, liver, and pancreatic attenuation and tumor conspicuity equal to or greater than that with multiphase CT, with a 43% reduction in radiation dose.

Embolization therapy for benign prostatic hyperplasia: Influence of embolization particle size on gland perfusion

To assess the influence of embolic size on the therapy response of prostatic arterial embolization (PAE) based on perfusional changes seen on dynamic contrast‐enhanced (DCE) magnetic resonance imaging (MRI).

Delayed Growth in Incidental Pancreatic Cysts: Are the Current American College of Radiology Recommendations for Follow-up Appropriate?

PURPOSE To evaluate growth kinetics of asymptomatic small (<2 cm) incidental pancreatic cysts and to assess potential implications of these in the context of current American College of Radiology recommendations. MATERIALS AND METHODS This institutional review board-approved HIPAA-compliant retrospective study with waiver of informed consent included patients with asymptomatic small incidental pancreatic cysts (diameter, 5-20 mm) with two or more magnetic resonance (MR) examinations performed at least 6 months apart at a tertiary institution. The largest cyst dimension was measured on T2-weighted single-shot fast spin-echo images by one of six radiologists (1-3 years of experience) who were trained to measure pancreatic cysts in a similar manner. All analysis was conducted at the patient level by choosing the cyst that exhibited the greatest growth over the follow-up period in each patient. Fisher exact, χ(2), and Kruskal-Wallis tests and analysis of variance were used to test correlation between cyst characteristics and growth. RESULTS A total of 259 patients (mean age, 65 years ± 11 [standard deviation], male-to-female ratio, 42:58) with 370 asymptomatic small incidental pancreatic cysts were included. At presentation, median cyst size was 9.4 mm (interquartile range [IQR], 7.0-12.2 mm), and 64 patients (25%; 95% confidence interval [CI]: 20, 30) had septations. The median imaging follow-up period was 2.2 years (IQR, 1.2-3.9 years; range, 0.5-11.0 years), with a median of three MR examinations (IQR, two to four examinations) per patient. In 171 (66%; 95% CI: 60, 72) of the 259 patients, cysts remained stable; in 18 (7%; 95% CI: 4, 11), cysts shrank; and in 70 (27%; 95% CI: 22, 33), cysts grew (median total growth and median annual growth of 4.8 mm and 2.3 mm/y, respectively). Age, cyst size, and cyst septation at presentation were not predictive of growth. Overall, 29 (11%), 16 (6%), and four (1.5%) of the cysts increased in size after 1, 2, and 3 years of initial stability, respectively. Of the 18 patients who underwent pancreatic surgery, only one patient with an intraductal papillary mucinous neoplasm had high-grade dysplasia. One patient developed pancreatic adenocarcinoma remotely at the location of the pancreatic cyst diagnosed 11 months prior. CONCLUSION In the majority of patients, asymptomatic small incidental pancreatic cysts remained stable during a median follow-up period of 2.2 years; however, in 27% of patients, cysts increased in size over time, with 11% growing after an initial 1-year period of stability. Current American College of Radiology recommendations to discontinue imaging follow-up after 1 year of stability may need to be reevaluated.

Prediction of Low versus High Recurrence Scores in Estrogen Receptor–Positive, Lymph Node–Negative Invasive Breast Cancer on the Basis of Radiologic-Pathologic Features: Comparison with Oncotype DX Test Recurrence Scores

Purpose To review mammographic, ultrasonographic (US), and magnetic resonance (MR) imaging features and pathologic characteristics of estrogen receptor (ER)-positive, lymph node-negative invasive breast cancer and to determine the relationship of these characteristics to Oncotype DX (Genomic Health, Redwood City, Calif) test recurrence scores (ODRS) for breast cancer recurrence. Materials and Methods This institutional review board-approved retrospective study was performed in a single large academic medical center. The study population included patients with ER-positive, lymph node-negative invasive breast cancer who underwent genomic testing from January 1, 2009, to December 31, 2013. Imaging features of the tumor were classified according to the Breast Imaging Reporting and Data System lexicon by breast imagers who were blinded to the ODRS. Mammography was performed in 86% of patients, US was performed in 84%, and MR imaging was performed in 33%, including morphologic and kinetic evaluation. Images from each imaging modality were evaluated. Each imaging finding, progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status, and tumor grade were then individually correlated with ODRS. Analysis of variance was used to determine differences for each imaging feature. Regression analysis was used to calculate prediction of recurrence on the basis of imaging features combined with histopathologic features. Results The 319 patients had a mean age ± standard deviation of 55 years ± 8.7 (range, 31-82 years). Imaging features with a positive correlation with ODRS included a well-circumscribed oval mass (P = .024) at mammography, vascularity (P = .047) and posterior enhancement (P = .004) at US, and lobulated mass (P = .002) at MR imaging. Recurrence scores were predicted by using these features in combination with PR and HER2 status and tumor grade by using the threshold of more than 30 as a high recurrence score. With a regression tree, there was correlation (r = 0.79) with 89% sensitivity and 83% specificity. Conclusion On the basis of preliminary data, information obtained routinely for breast cancer diagnosis can reliably be used to predict the ODRS with high sensitivity and specificity. (©) RSNA, 2016.

Need for intraoperative ultrasound and surgical recommendation for partial nephrectomy: correlation with tumor imaging features and urologist practice patterns.

Purpose This study aimed to evaluate the need for intraoperative ultrasound (IOUS) and recommendation for surgical approach in the resection of renal tumors through a survey of practicing urologists, with correlation to tumor imaging features and urologist practice pattern. Materials and Methods An institutional review board–approved retrospective review, compliant with the Health Insurance Portability and Accountability Act, of 44 renal tumors that underwent laparoscopic partial nephrectomy at the study institution was performed. The numeric component of the RENAL nephrometry score (radius [diameter], % exophytic, nearness [to collecting system/renal sinus], location) was calculated for each case using preoperative computed tomography/magnetic resonance imaging. Five anonymized images of each tumor were presented to 4 academic urologists with varying practice patterns. Reviewers independently scored each case for its need for IOUS, for recommendation of a surgical technique, and for the difficulty of the proposed surgery. Results The RENAL scores were as follows: RENAL 1 (low complexity, score 4–6; n = 19); RENAL 2 (moderate complexity, score 7–9; n = 23); RENAL 3 (high complexity, score 10–12; n = 2). The only RENAL score component significantly influencing need for IOUS was percentage exophytic (P = 0.00002). There was an inverse relationship between normalized and averaged need for IOUS and percentage exophytic (P < 0.0001). The predominant influence for recommendation of surgical method was the reviewer him/herself, with each reviewer’s recommendations closely matching his/her practice pattern. Size and percentage exophytic represented the only tumor features significantly (P = 0.03) influencing surgical recommendation. Conclusions There was a significant difference in the perceived need for IOUS and surgical recommendation when 4 academic urologists reviewed a series of renal masses requiring resection. Percentage exophytic correlated inversely with need for IOUS. Urologist’s practice pattern and tumor size and percentage exophytic were most predictive of surgical recommendation.

Effect of Stereotactic Body Radiotherapy on the Growth Kinetics and Enhancement Pattern of Primary Renal Tumors

OBJECTIVE The objective of our study was to assess the growth rate and enhancement of renal masses before and after treatment with stereotactic body radiotherapy (SBRT). MATERIALS AND METHODS This retrospective study included all patients with renal masses who underwent SBRT during a 5-year period. Orthogonal measurements of renal masses were obtained on pre- and posttreatment CT or MRI. Pre- and posttreatment growth rates were compared for renal mass diameter and volume using the t test. Pre- and posttreatment tumor enhancement values were compared for tumors that underwent multiphasic contrast-enhanced MRI. RESULTS Forty patients underwent SBRT for the treatment of 41 renal tumors: clear cell renal cell carcinomas (RCCs) (n = 16), papillary RCCs (n = 6), oncocytic neoplasms (n = 8), unclassified RCCs (n = 2), urothelial carcinoma (n = 1), and no pathologic diagnosis (n = 8). The mean maximum tumor diameter before treatment was 3.9 cm (range, 1.6-8.3 cm). Three hundred thirty-eight pre- and posttreatment imaging studies were analyzed: 214 MRI studies and 124 CT studies. The mean pre- and posttreatment lengths of observation were 416 days (range, 2-1800 days) and 561 days (83-1366 days), respectively. The mean pretreatment tumor growth rate of 0.68 cm/y decreased to -0.37 cm/y post treatment (p < 0.0001), and the mean tumor volume growth rate of 21.2 cm(3)/y before treatment decreased to -5.35 cm(3)/y after treatment (p = 0.002). Local control-defined as less than 5 mm of growth-was achieved in 38 of 41 (92.7%) tumors. The Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 showed progression in one tumor (2.4%), stability in 31 tumors (75.6%), partial response in eight tumors (19.5%), and complete response in one tumor (2.4%). No statistically significant change in tumor enhancement was shown (mean follow-up, 142 days; range, 7-581 days). CONCLUSION Renal tumors treated with SBRT show statistically significant reductions in growth rate and tumor size after treatment but do not show statistically significant differences in enhancement in the initial (mean, 142 days) posttreatment period.

MR Enterography of the Ileoanal Pouch: Descriptive Radiologic Analysis With Endoscopic and Pathologic Correlation

OBJECTIVE The purpose of this study was to describe the MR enterography (MRE) appearance of inflammation of the ileoanal pouch after ileal pouch-anal anastomosis (IPAA) surgery and to correlate it with pouch endoscopic and histopathologic findings. MATERIALS AND METHODS All MRE studies performed between October 1, 2007, and September 30, 2013, for patients who had previously undergone IPAA (n = 54) were retrieved. After review of medical records, the patients who underwent MRE, pouch endoscopy, and biopsy within 90 days (14 men, 14 women; mean age, 42.2 years; range, 24-67 years) were selected for inclusion in the study. Two blinded MRI radiologists in consensus retrospectively evaluated MRE studies for multiple MRI features. Two MRI scores were then calculated: an active and a composite inflammation score. A gastroenterologist retrospectively reviewed the pouch endoscopic images, and a pathologist reviewed the slides; both of these investigators were blinded. Both MRI scores were correlated with the pouch endoscopic and histopathologic findings. RESULTS The composite MRI score had strong positive correlation with the endoscopic score (r = 0.61; p = 0.0005) but weak positive correlation with the histopathologic score (r = 0.31; p = 0.10, not statistically significant). The active inflammation MRI score had moderate positive correlation with the endoscopic score (r = 0.57; p = 0.0017) and weak positive correlation with the histopathologic score (r = 0.20; p = 0.31, not statistically significant). An MRI score ≥ 4 indicated the best results, with sensitivity of 86%, specificity of 79%, positive predictive value of 80%, negative predictive value of 85%, and accuracy of 82% for pouch inflammation. A positive likelihood ratio of 4.00 and negative likelihood ratio of 0.18 were obtained. CONCLUSION In patients who have undergone IPAA surgery, the MRE findings strongly correlate with the pouch endoscopic findings with high sensitivity and positive predictive value for pouch inflammation. Therefore, MRE is a useful noninvasive test performed without ionizing radiation that can be used to evaluate patients with clinical symptoms and possibly alleviate the need for endoscopy in a select patient population.

Surgical upgrade rate of breast atypia to malignancy: An academic center's experience and validation of a predictive model

Atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS) are commonly seen on breast core needle biopsy (CNB). Many institutions recommend excision of these lesions to exclude malignancy. A retrospective chart review was performed on patients who had ADH, ALH, or LCIS on breast CNB from 1/1/08 to 12/31/10 who subsequently had surgical excision of the biopsy site. Study objectives included determining upgrade to malignancy at surgical excision, identification of predictors of upgrade, and validation of a recently published predictive model. Clinical and demographic factors, pathology, characteristics of the biopsy procedure and visible residual lesion were recorded. T test and chi‐squared test were used to identify predictors. Classification tree was used to predict upgrade. 151 patients had mean age of 53 years. The mean maximum lesion size on imaging was 11 mm. The primary atypia was ADH in 63.6%, ALH in 27.8%, and LCIS in 8.6%. 16.6% of patients had upgrade to malignancy, with 72% DCIS and 28% invasive carcinoma. Risk factors for upgrade included maximum lesion size (P = .002) and radiographic presence of residual lesion (P = .001). A predictive model based on these factors had sensitivity 78%, specificity 80% and AUC = 0.88. Validating a published nomogram with our data produced accuracy figures (AUC = 0.65) within published CI of 0.63‐0.82. In CNB specimens containing ADH, ALH, or LCIS, initial lesion size and presence of residual lesion are predictors of upgrade to malignancy. A validated model may be helpful in developing patient management strategies.

Ovarian Cancer: Prevalence in Incidental Simple Adnexal Cysts Initially Identified in CT Examinations of the Abdomen and Pelvis

Purpose To evaluate the rate of malignancy in incidentally detected simple adnexal cysts at computed tomography (CT) to determine if simple-appearing cysts require follow-up. Materials and Methods In this HIPAA-compliant, institutional review board-approved retrospective cohort study, an institutional database was searched for abdominal and pelvic CT studies performed between June 2003 and December 2010 in women reported to have adnexal cysts. Adnexal cyst characterization was determined by prospective report description as well as image review by a research fellow and by a fellowship-trained abdominal radiologist for examinations with disagreement between the original report and the research fellows assessment. Patients with known ovarian cysts or ovarian cancer at time of the index CT examination were excluded. Clinical outcome was assessed by using follow-up imaging studies, medical records, and the state cancer registry. Benign outcome was determined by benign findings at surgery, a decrease in size or resolution of a simple-appearing cyst at follow-up imaging, or stability of the cyst for at least 1 year. Descriptive statistics and 95% confidence intervals (CIs) were calculated. Results Among 42 111 women who underwent abdominal and pelvic CT examinations in the study period, 2763 (6.6%; 95% CI: 6.3%, 6.8%) (mean age, 48.1 years ± 18.1; range, 15-102 years) had a newly detected finding of ovarian cyst described in the body or impression section of the report. Median cyst size was 3.1 cm (range, 0.8-20.0 cm). Eighteen (0.7%; 95% CI: 0.4%, 1.0%) of 2763 patients were found to have ovarian cancer after an average follow-up of 5.1 years ± 3.8 (range, 0-12.8 years). None (95% CI: 0%, 0.4%) of 1031 women with simple-appearing cysts were given a diagnosis of ovarian cancer. This included none (95% CI: 0%, 0.4%) of 904 women with simple-appearing cysts with an adequate reference standard for benign outcome. Conclusion The prevalence of previously unknown adnexal cysts at CT was 6.6%, with an ovarian cancer rate of 0.7% (95% CI: 0.4%, 1.0%). All simple-appearing cysts were benign (95% CI: 99.6%, 100%).