The Role of Imaging for Gastrointestinal Bleeding: Consensus Recommendations From the American College of Gastroenterology and Society of Abdominal Radiology.

Gastrointestinal (GI) bleeding is the most common GI diagnosis leading to hospitalization within the United States. Prompt diagnosis and treatment of GI bleeding is critical to improving patient outcomes and reducing high healthcare utilization and costs. Radiologic techniques including computed tomography angiography, catheter angiography, computed tomography enterography, magnetic resonance enterography, nuclear medicine red blood cell scan, and technetium-99m pertechnetate scintigraphy (Meckel scan) are frequently used to evaluate patients with GI bleeding and are complementary to GI endoscopy. However, multiple management guidelines exist which differ in the recommended utilization of these radiologic examinations. This variability can lead to confusion as to how these tests should be used in the evaluation of GI bleeding. In this document, a panel of experts from the American College of Gastroenterology and Society of Abdominal Radiology provide a review of the radiologic examinations used to evaluate for GI bleeding including nomenclature, technique, performance, advantages, and limitations. A comparison of advantages and limitations relative to endoscopic examinations is also included. Finally, consensus statements and recommendations on technical parameters and utilization of radiologic techniques for GI bleeding are provided.

The Role of Imaging for GI Bleeding: ACG and SAR Consensus Recommendations.

Gastrointestinal (GI) bleeding is the most common GI diagnosis leading to hospitalization within the United States. Prompt diagnosis and treatment of GI bleeding is critical to improving patient outcomes and reducing high health care utilization and costs. Radiologic techniques including CT angiography, catheter angiography, CT enterography, MR enterography, nuclear medicine red blood cell scan, and technetium-99m pertechnetate scintigraphy (Meckel scan) are frequently used to evaluate patients with GI bleeding and are complementary to GI endoscopy. However, multiple management guidelines exist, which differ in the recommended utilization of these radiologic examinations. This variability can lead to confusion as to how these tests should be used in the evaluation of GI bleeding. In this document, a panel of experts from the American College of Gastroenterology and Society of Abdominal Radiology provide a review of the radiologic examinations used to evaluate for GI bleeding including nomenclature, technique, performance, advantages, and limitations. A comparison of advantages and limitations relative to endoscopic examinations is also included. Finally, consensus statements and recommendations on technical parameters and utilization of radiologic techniques for GI bleeding are provided. © Radiological Society of North America and the American College of Gastroenterology, 2024. Supplemental material is available for this article. This article is being published concurrently in American Journal of Gastroenterology and Radiology. The articles are identical except for minor stylistic and spelling differences in keeping with each journal's style. Citations from either journal can be used when citing this article. See also the editorial by Lockhart in this issue.

Dual-Energy CT Evaluation of Gastrointestinal Bleeding.

Gastrointestinal (GI) bleeding is a potentially life-threatening condition accounting for more than 300 000 annual hospitalizations. Multidetector abdominopelvic CT angiography is commonly used in the evaluation of patients with GI bleeding. Given that many patients with severe overt GI bleeding are unlikely to tolerate bowel preparation, and inpatient colonoscopy is frequently limited by suboptimal preparation obscuring mucosal visibility, CT angiography is recommended as a first-line diagnostic test in patients with severe hematochezia to localize a source of bleeding. Assessment of these patients with conventional single-energy CT systems typically requires the performance of a noncontrast series followed by imaging during multiple postcontrast phases. Dual-energy CT (DECT) offers several potential advantages for performing these examinations. DECT may eliminate the need for a noncontrast acquisition by allowing the creation of virtual noncontrast (VNC) images from contrast-enhanced data, affording significant radiation dose reduction while maintaining diagnostic accuracy. VNC images can help radiologists to differentiate active bleeding, hyperattenuating enteric contents, hematomas, and enhancing masses. Additional postprocessing techniques such as low-kiloelectron voltage virtual monoenergetic images, iodine maps, and iodine overlay images can increase the conspicuity of contrast material extravasation and improve the visibility of subtle causes of GI bleeding, thereby increasing diagnostic confidence and assisting with problem solving. GI bleeding can also be diagnosed with routine single-phase DECT scans by constructing VNC images and iodine maps. Radiologists should also be aware of the potential pitfalls and limitations of DECT. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Gastrointestinal Bleeding at CT Angiography and CT Enterography: Imaging Atlas and Glossary of Terms.

Gastrointestinal (GI) bleeding is a common potentially life-threatening medical condition frequently requiring multidisciplinary collaboration to reach the proper diagnosis and guide management. GI bleeding can be overt (eg, visible hemorrhage such as hematemesis, hematochezia, or melena) or occult (eg, positive fecal occult blood test or iron deficiency anemia). Upper GI bleeding, which originates proximal to the ligament of Treitz, is more common than lower GI bleeding, which arises distal to the ligament of Treitz. Small bowel bleeding accounts for 5-10% of GI bleeding cases commonly manifesting as obscure GI bleeding, where the source remains unknown after complete GI tract endoscopic and imaging evaluation. CT can aid in identifying the location and cause of bleeding and is an important complementary tool to endoscopy, nuclear medicine, and angiography in evaluating patients with GI bleeding. For radiologists, interpreting CT scans in patients with GI bleeding can be challenging owing to the large number of images and the diverse potential causes of bleeding. The purpose of this pictorial review by the Society of Abdominal Radiology GI Bleeding Disease-Focused Panel is to provide a practical resource for radiologists interpreting GI bleeding CT studies that reviews the proper GI bleeding terminology, the most common causes of GI bleeding, key patient history and risk factors, the optimal CT imaging technique, and guidelines for case interpretation and illustrates many common causes of GI bleeding. A CT reporting template is included to help generate radiology reports that can add value to patient care. An invited commentary by Al Hawary is available online. Online supplemental material is available for this article. ©RSNA, 2021.

Small Bowel Crohn Disease at CT and MR Enterography: Imaging Atlas and Glossary of Terms.

Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society for Pediatric Radiology, the American Gastroenterological Association, and other international experts recently reported consensus recommendations for standardized nomenclature for the interpretation and reporting of CT enterography and MR enterography findings of small bowel Crohn disease. The consensus recommendations included CT enterography and MR enterography bowel wall findings that are associated with Crohn disease, findings that occur with penetrating Crohn disease, and changes that occur in the mesentery related to Crohn disease. Also included were recommended radiology report impression statements that summarize the findings of small bowel Crohn disease at CT enterography and MR enterography. This article, authored by the Society of Abdominal Radiology Crohn's Disease-Focused Panel, illustrates the imaging findings and recommended radiology report impression statements described in the consensus recommendations with examples of CT enterography and MR enterography images. Additional interpretation guidelines for reporting CT enterography and MR enterography examinations are also presented. The recommended standardized nomenclature can be used to generate radiology report dictations that will help guide medical and surgical management for patients with small bowel Crohn disease. Online supplemental material is available for this article. ©RSNA, 2020See discussion on this article by Heverhagen.

Image-Guided Cholecystostomy Tube Placement: Short- and Long-Term Outcomes of Transhepatic Versus Transperitoneal Placement.

OBJECTIVE: Image-guided percutaneous cholecystostomy may be performed by a transhepatic or transperitoneal approach. We compared the short- and long-term outcomes of percutaneous cholecystostomy related to route of catheter placement. MATERIALS AND METHODS: A retrospective observational study of image-guided percutaneous cholecystostomy was performed from 2004 to 2016. A search of the hospital's radiology information service was performed using the keywords "percutaneous cholecystostomy," "gallbladder drain," and "cholecystostomy tube" and the relevant Current Procedural Terminology codes. All search results were reviewed to identify the cohort of 373 patients who underwent initial percutaneous cholecystostomy catheter placement. Imaging was reviewed to determine the method and route of percutaneous cholecystostomy and complications. A chart review was performed to determine clinical outcomes. Differences were examined using a generalized linear model assuming a binary distribution and logit function. RESULTS: Percutaneous cholecystostomy catheter placement was performed using ultrasound guidance alone in 229 patients, ultrasound access with fluoroscopic guidance in 129 patients, CT guidance in 14 patients, and fluoroscopic guidance in one patient. The trocar technique was used for 183 patients, and the Seldinger technique was used for 190 patients. Two hundred eighteen percutaneous cholecystostomy catheters were placed via the transhepatic route, and 153 were placed via the transperitoneal route. The most common catheter sizes used were 8.5 French (n = 234) and 10 French (n = 124). No significant differences were observed between transperitoneal and transhepatic placement with regard to the frequency of pain, clogging, skin infection, bleeding, biloma, cholangitis, leakage, abscess, unplanned catheter removal, or need for replacement (p > 0.05). CONCLUSION: No evidence of a difference in outcomes was observed for transhepatic cholecystostomy tube placement over transperitoneal placement. The route that appears safer and less technically challenging should therefore be chosen.

MR enterography in Crohn's disease: current consensus on optimal imaging technique and future advances from the SAR Crohn's disease-focused panel.

MR enterography is a powerful tool for the non-invasive evaluation of patients with Crohn's disease (CD) without ionizing radiation. The following paper describes the current consensus on optimal imaging technique, interpretation, and future advances from the Society of Abdominal Radiology CD-focused panel.

Management of nodules with initially nondiagnostic results of thyroid fine-needle aspiration: can we avoid repeat biopsy?

PURPOSE: To identify demographic and ultrasonographic (US) features associated with malignancy after initially nondiagnostic results of fine-needle aspiration (FNA) to help clarify the role of repeat FNA, surgical excision, or serial US in these nodules. MATERIALS AND METHODS: This study was HIPAA compliant and institutional review board approved; informed consent was waived. Thyroid nodules (n = 5349) that underwent US-guided FNA in 2004-2012 were identified; 393 were single nodules with nondiagnostic FNA results but adequate cytologic, surgical, or US follow-up. Demographic information and diameters and volume at US at first biopsy were modeled with malignancy as outcome through medical record review. Exact logistic regression was used to model malignancy outcomes, demographic comparisons with age were made (Student t test, Satterthwaite test), and proportion confidence intervals (CIs) were estimated (Clopper-Pearson method). RESULTS: Of 393 nodules with initially nondiagnostic results, nine malignancies (2.3%) were subsequently diagnosed with repeat FNA (n = 2, 0.5%) or surgical pathologic examination (n = 7, 1.8%), 330 (84.0%) were benign, and 54 (13.7%) were stable or decreased in size at serial US (mean follow-up, 3.0 years; median, 2.5 years; range, 1.0-7.8 years). Patients with malignancies were significantly older (mean age, 62.7 years; median, 64 years; range, 47-77 years) than those without (mean age, 55.4 years; median, 57 years; range, 12-94 years; P = .0392). Odds of malignancy were 4.2 times higher for men versus women (P = .045) and increased significantly for each 1-cm increase in anteroposterior, minimum, and mean nodule diameter (1.78, 2.10, and 1.96, respectively). In 393 nodules, no malignancies were detected in cystic or spongiform nodules (both, n = 11, 2.8%; 95% CI: 1.4%, 5.0%), nodules with eggshell calcifications (n = 9, 2.3%; 95% CI: 1.1%, 4.3%), or indeterminate echogenic foci (n = 39, 9.9%; 95% CI: 7.2%, 13.3%). CONCLUSION: Very few malignancies were diagnosed with repeat FNA following nondiagnostic FNA results (two of 336, 0.6%); therefore, clinical and US follow-up may be more appropriate than repeat FNA following nondiagnostic biopsy results.

Gastric band slippage: a case-controlled study comparing new and old radiographic signs of this important surgical complication.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of four radiographic signs of gastric band slippage: abnormal phi angle, the "O sign," inferior displacement of the superolateral gastric band margin, and presence of an air-fluid level above the gastric band. MATERIALS AND METHODS: A search of the electronic medical record identified 21 patients with a surgically proven slipped gastric band and 63 randomly-selected asymptomatic gastric band patients who had undergone barium swallow studies. These studies were evaluated for the four signs of band slippage by two independent radiologists who were blinded to clinical data. Sensitivity, specificity, and positive and negative predictive values were calculated for each radiographic sign of band slippage. Interobserver agreement between radiologists was assessed using the Fleiss kappa statistic. RESULTS: In evaluating for gastric band slippage, an abnormal phi angle greater than 58° was 91-95% sensitive and 52-62% specific (κ = 0.78), the O sign was 33-48% sensitive but 97% specific (κ = 0.84), inferior displacement of the superolateral band margin by more than 2.4 cm from the diaphragm was 95% sensitive and 97-98% specific (κ = 0.97), and the presence of an air-fluid level was 95% sensitive and 100% specific (κ = 1.00). CONCLUSION: We report two previously undescribed radiographic signs of gastric band slippage that are both sensitive and specific for this important surgical complication and recommend that these signs should be incorporated into the imaging evaluation of gastric band patients.

Reducing radiation dose at CT colonography: decreasing tube voltage to 100 kVp.

PURPOSE: To assess the effect of a decrease in tube voltage from 120 kVp to 100 kVp on dose, contrast-to-noise ratio (CNR), and three-dimensional (3D) image quality in patients undergoing computed tomographic (CT) colonography as well as to determine how these changes are affected by patient size. MATERIALS AND METHODS: This HIPAA-compliant and institutional review board-approved retrospective study included 63 consecutive patients who underwent CT colonography and who waived informed consent. Scanning was performed with patients in the supine (120 kVp) and prone (100 kVp) positions, with other parameters unchanged. Volume CT dose index (CTDI(vol)), dose-length product (DLP), image noise, attenuation of selected materials, and CNR were compared with the Wilcoxon matched-pairs signed rank test. Two readers blinded to tube voltage independently assessed 3D endoluminal image quality. The k coefficients were calculated for interobserver agreement. Average image quality ratings were compared with the Wilcoxon signed rank test. All recorded data were stratified by patient anteroposterior diameter to determine effects of patient size. RESULTS: Decreasing tube voltage from 120 to 100 kVp resulted in a 20% decrease in CTDI(vol) (P < .001) and a 16% decrease in DLP (P < .001). Image noise increased by 32% (P < .001). Mean attenuation of tagged fluid increased from 395 to 487 HU (P < .001). There was no change in mean CNR of tagged fluid (17.1 at 120 kVp, 16.8 at 100 kVp; P = .37), regardless of patient size. The 3D image quality decreased slightly from a median score of 5 out of 5 to 4 out of 5 (P < .001). There was substantial interobserver agreement. CONCLUSION: A decrease in tube voltage from 120 to 100 kVp results in a significant decrease in radiation dose but only a minimal decrease in 3D image quality at all patient sizes. © RSNA, 2012.

Morphologic features of 211 adrenal masses at initial contrast-enhanced CT: can we differentiate benign from malignant lesions using imaging features alone?

OBJECTIVE: The objective of our study was to determine whether morphologic features of adrenal masses detected at initial contrast-enhanced MDCT can differentiate benign from malignant disease. MATERIALS AND METHODS: Two hundred eleven adrenal masses (1-4 cm) detected during standard contrast-enhanced MDCT with a proven final diagnosis were retrospectively identified in 188 patients through a computer search of CT, PET/CT, and pathology reports. Three authors blinded to the diagnoses independently reviewed the contrast-enhanced MDCT images of the adrenal masses and evaluated their morphologic features: lesion margin (smooth, lobulated, or irregular), density (homogeneous or heterogeneous), and additional features of central low density and enhancing rim. Using these criteria, the readers categorized each mass as probably benign, indeterminate, or suspicious. RESULTS: There were 171 (81%) benign and 40 (19%) malignant adrenal masses. All malignant masses were metastases diagnosed in patients with known extraadrenal malignancy. For individual morphologic features in diagnosing malignancy, irregular margins had 30-33% sensitivity and 95-96% specificity and an enhancing rim had 5-13% sensitivity and 98-99% specificity. None of the imaging features was reliable in predicting benignity. When an adrenal mass was deemed suspicious by a reader, the sensitivities for malignancy ranged from 54% to 74% and specificities from 96% to 97%. Notably, no malignant lesions occurred in patients without a known history of cancer. CONCLUSION: At routine contrast-enhanced MDCT, adrenal masses with irregular margins or a thick enhancing rim are likely to be malignant. Smooth margins and homogeneous density can be seen in both benign and malignant adrenal masses and are insufficient for characterization.

Inadvertent ingestion of wire bristles from a grill cleaning brush: radiologic detection of unsuspected foreign bodies.

OBJECTIVE: We report acute onset of either odynophagia or abdominal pain immediately after ingestion of grilled meat in six patients presenting between May 1, 2009, and November 18, 2010. In all six patients, radiologic studies revealed a linear metallic foreign body. Careful history revealed cleaning of the grill with a metallic brush immediately before cooking in all six cases. CONCLUSION: Physicians should be aware of this potential hazard to facilitate accurate and timely diagnosis.

Review of CT-guided trans-osseous biopsies.

Percutaneous image-guided biopsy is an invaluable technique in the management of a myriad of different conditions; however, percutaneous access to some targets remains challenging. Trans-osseous biopsy provides safe, high-yield access to many challenging lesions in the chest, abdomen, and pelvis which might otherwise require more invasive procedures, such as mediastinoscopy or surgery to establish a histological diagnosis. Additionally, trans-osseous biopsy is well tolerated and may reduce the risk of injury to intervening vital structures as compared to other percutaneous techniques. In this article we review the indications, technical challenges, alternative techniques, and potential complications of trans-sternal, trans-costal, trans-scapular, trans-vertebral, trans-iliac, and trans-sacral biopsies.

Management of gastrointestinal bleeding: Society of Abdominal Radiology (SAR) Institutional Survey.

Despite guidelines developed to standardize the diagnosis and management of gastrointestinal (GI) bleeding, significant variability remains in recommendations and practice. The purpose of this survey was to obtain information on practice patterns for the evaluation of overt lower GI bleeding (LGIB) and suspected small bowel bleeding. A 34-question electronic survey was sent to all Society of Abdominal Radiology (SAR) members. Responses were received from 52 unique institutions (40 from the United States). Only 26 (50%) utilize LGIB management guidelines. 32 (62%) use CT angiography (CTA) for initial evaluation in unstable patients. In stable patients with suspected LGIB, CTA is the preferred initial exam at 21 (40%) versus colonoscopy at 24 (46%) institutions. CTA use increases after hours for both unstable (n = 32 vs. 35, 62% vs. 67%) and stable patients (n = 21 vs. 27, 40% vs 52%). CTA is required before conventional angiography for stable (n = 36, 69%) and unstable (n = 15, 29%) patients. 38 (73%) institutions obtain two post-contrast phases for CTA. 49 (94%) institutions perform CT enterography (CTE) for occult small bowel bleeding with capsule endoscopy (n = 26, 50%) and CTE (n = 21, 40%) being the initial test performed. 35 (67%) institutions perform multiphase CTE for occult small bowel bleeding. In summary, stable and unstable patients with overt lower GI are frequently imaged with CTA, while CTE is frequently performed for suspected occult small bowel bleeding.

Incidence of multiple sporadic renal cell carcinomas in patients referred for renal radiofrequency ablation: implications for imaging follow-up.

OBJECTIVE: The objective of our study was to report the incidence of multiple sporadic primary renal cell carcinomas (RCCs) in patients referred for radiofrequency ablation (RFA). MATERIALS AND METHODS: A retrospective search identified 162 patients (104 men and 58 women; mean age, 74 years) without a history of von Hippel-Lindau disease with a total of 175 tumors treated with RFA for biopsy-proven primary renal malignancies at our institution from 1998 to 2009. Three groups of patients with multiple RCCs were identified: patients with a history of nephrectomy for RCC who had been referred for RFA of a new renal tumor, patients who presented with multiple renal tumors at the time of referral for RFA, and patients who were shown to have developed a new renal tumor on follow-up imaging after RFA. RESULTS: Twenty-eight patients (17%) had multiple biopsy-proven RCCs. Eighteen patients (11%) had undergone prior nephrectomy for surgically proven RCC. The mean interval between prior nephrectomy and RFA referral was 122 months (range, 12-456 months). Seven patients (4%) without a history of nephrectomy presented with two biopsy-proven RCCs at RFA referral. Three patients (2%) who had not undergone nephrectomy and had a solitary RCC at the time of RFA had developed a new biopsy-proven RCC separate from the original treatment site on follow-up imaging after RFA. The mean time to diagnosis from the initial RFA treatment was 52 months (range, 25-89 months). CONCLUSION: Imaging surveillance of patients referred for renal RFA may be important not only to assess treatment success but also to detect new RCCs.

Dynamic MDCT for localization of occult parathyroid adenomas in 26 patients with primary hyperparathyroidism.

OBJECTIVE: The objective of our study was to evaluate the accuracy of dynamic contrast-enhanced 4D MDCT in the preoperative identification of parathyroid adenomas in patients with primary hyperparathyroidism (PHPT) and a history of failed surgery or unsuccessful localization on standard imaging. MATERIALS AND METHODS: Thirty-four patients with PHPT underwent 4D CT. Retrospective blinded review of the 4D CT examinations was performed by three radiologists for the presence and location of a suspected parathyroid adenoma or adenomas. At the time of the study, 25 patients underwent surgical exploration after 4D CT. Twenty patients had solitary parathyroid adenomas, two patients had two adenomas resected, two patients did not have an adenoma, and one patient had mild four-gland hyperplasia. One patient did not have PHPT on repeat serum biochemistry. Surgical and pathology reports, adenoma enhancement, and biochemical and clinical follow-up were reviewed. Data were compared with 4D CT interpretations and interobserver reliability was calculated. RESULTS: The mean sensitivity and specificity of the three readers for the precise CT localization of adenomas was 82% (range, 79-88%) and 92% (range, 75-100%), respectively. Overall interobserver reliability was excellent (κ = 0.70; range, κ = 0.60-0.79). All adenomas resected at surgery showed a biochemical response and clinical response. The mean densities of the confirmed adenomas were 41, 128, 138, and 109 HU at 0, 30, 60, and 90 seconds, respectively. Level II lymph nodes identified in 10 patients showed significantly less enhancement at 30 (p = 0.0001) and 60 (p = 0.006) seconds compared with surgically proven adenomas. CONCLUSION: Occult parathyroid adenoma shows characteristic early enhancement. In this subset of patients, 4D CT may improve surgical outcomes and decrease morbidity.

MRE Evaluation of Intestinal Inflammation: Qualitative and Quantitative Assessment.

ABSTRACT: Magnetic resonance enterography (MRE) is a powerful tool for evaluation and management of patients with Crohn disease. Changes of active inflammation of the small bowel can reliably and reproducibly be detected and monitored. Findings indicative of active inflammation include bowel wall thickening, intramural edema and mural hyperenhancement. These changes are most commonly reported qualitatively; however, quantitative indices have also been developed and validated to measure and monitor inflammation both for clinical care and research purposes. This article describes the essential findings of active inflammation on MRE as well as the fundamentals of both qualitative and quantitative assessment and reporting.

Optimum imaging of colorectal metastases.

Dramatic improvements in diagnostic imaging have developed with and enabled increasingly sophisticated treatments for metastatic colorectal cancer. Advances in therapeutic techniques, such as surgical resection and percutaneous therapies, demand that diagnostic imaging provide an accurate assessment of disease burden as well as precise localization. In this article, we present the current state-of-the-art of diagnostic imaging for evaluation of metastatic colorectal cancer.

Diffusion-weighted MRI of peripheral zone prostate cancer: comparison of tumor apparent diffusion coefficient with Gleason score and percentage of tumor on core biopsy.

OBJECTIVE: The objective of our study was to determine the relationship between the apparent diffusion coefficient (ADC) value on diffusion-weighted imaging (DWI) and Gleason score of prostate cancer and percentage of tumor involvement on prostate core biopsy. MATERIALS AND METHODS: We performed a retrospective study of 57 patients with biopsy-proven prostate cancer who underwent endorectal MRI with DWI between July 2007 and March 2008. Regions of interest (ROIs) were drawn on ADC maps at sites of visible tumor on DW images and ADC maps. A hierarchic mixed linear model was used to compare the ADC value of prostate cancer with the Gleason score and the percentage of tumor on core biopsy. RESULTS: Eighty-one sites of biopsy-proven prostate cancer were visible on DW images and ADC maps. The least-squares mean ADC for disease with a Gleason score of 6 was 0.860 x 10(-3) mm(2)/s (standard error of the mean [SEM], 0.036); Gleason score of 7, 0.702 x 10(-3) mm(2)/s (SEM, 0.030); Gleason score of 8, 0.672 x 10(-3) mm(2)/s (SEM, 0.057); and Gleason score of 9, 0.686 x 10(-3) mm(2)/s (SEM, 0.067). Differences between the mean ADC values for a prostate tumor with a Gleason score of 6 and one with a Gleason score of 7 (p = 0.0096) and for a prostate tumor with a Gleason score of 6 and one with a Gleason score of 8 (p = 0.0460) were significant. Comparison between the ADC and percentage of tumor on core biopsy showed a mean ADC decrease of 0.006 (range, 0.004-0.008 x 10(-3) mm(2)/s) for every 1% increase in tumor in the core biopsy specimen. CONCLUSION: DWI may help differentiate between low-risk (Gleason score, 6) and intermediate-risk (Gleason score, 7) prostate cancer and between low-risk (Gleason score, 6) and high-risk (Gleason score > 7) prostate cancer. There is an inverse relationship between the ADC and the percentage of tumor involvement on prostate core biopsies.

Three contrast injection protocols for electrocardiogram-gated 64-slice computed tomographic angiography: comparing vessel density and perceived quality.

OBJECTIVE: To compare aortic, pulmonary artery (PA), and coronary artery (CA) density and examination quality using 3 different injection protocols for electrocardiogram-gated 64-detector row computed tomographic angiography. METHODS: We reviewed 30 consecutive computed tomographic angiography studies for each of 3 different contrast protocols (A, B, and C)-90 studies total-performed in patients with chest pain and low to moderate suspicion for coronary disease. All used a 20-mL timing bolus followed by 30 mL of saline. Protocol A (PrA) was composed of 50-mL contrast at 5 mL/s, 40-mL contrast/10-mL saline at 4 mL/s, and 40-mL saline at 4 mL/s. Protocol B (PrB) was composed of 50-mL contrast at 5 mL/s, 30- to 50-mL contrast at 3.5 mL/s (timing bolus-dependent), and 50-mL saline at 3.5 mL/s. Protocol C (PrC) was composed of 60-mL contrast at 5.5 mL/s, 50-mL contrast at 4.5 mL/s, and 50-mL saline at 3.5 mL/s. Density measurements were made at 20 points. Studies were graded for quality on a 4-point scale. RESULTS: Main PA density for PrA (263 Hounsfield units [HU]) was significantly lower than for PrB (335 HU) and PrC (366 HU). For PrA, PrB, and PrC, there were 10, 1, and 1 nondiagnostic PA studies, respectively; the numbers of good or very good quality studies were 10, 21, and 25. Left main CA densities for PrA (393 HU), PrB (353 HU), and PrC (356 HU) were not significantly different; likewise for aortic root densities (400, 375, and 372 HU). For the aortic root, the numbers of good or very good studies were 30, 27, and 28. Grade (G) is linearly related to average density per grade (D): G = 0.011 × D - 1.46, r = 0.96. CONCLUSIONS: Protocols B and C yielded consistently high attenuation of the aorta, PAs, and CAs with commensurate examination quality.