Bryan R. Foster

Integration of 64-Detector Lower Extremity CT Angiography into Whole-Body Trauma Imaging: Feasibility and Early Experience

PURPOSE To evaluate the image quality and clinical utility of a polytrauma computed tomographic (CT) protocol that integrates lower extremity CT angiography into multiphasic whole-body trauma CT by utilizing 64-detector CT and a single contrast material bolus. MATERIALS AND METHODS This retrospective study was institutional review board approved and HIPAA compliant. Informed consent was waived. All patients who underwent CT angiography of the lower extremities integrated with multiphasic torso CT for trauma between May 2005 and September 2009 were included. Two hundred eighty-four patients met the inclusion criteria. The mechanism of trauma was blunt injury in 228 (80.3%) of 284 patients and penetrating in 56 (19.7%) of 284 patients. CT angiography encompassed the joints proximal and distal to the injured region, with scan delay fixed at 25 seconds. Two radiologists retrospectively reviewed all the extremity CT angiograms, noting the presence of vascular injury, and measured the attenuation in the lower extremity arteries. Arterial attenuation, in Hounsfield units, was measured at multiple vascular divisions, and CT angiographic results were compared with clinical outcome, and if available, repeat lower extremity CT angiographic, conventional angiographic, or surgical findings. Sensitivity and specificity with 95% confidence intervals were calculated. RESULTS Sixty-three arterial injuries were identified in 44 (15.5%) of 284 patients as follows: occlusion (n = 37), narrowing (n = 9), active extravasation (n = 14), pseudoaneurysm (n= 2), and arteriovenous fistula (n = 1). Three patients underwent conventional angiography after CT angiography. Seven patients underwent surgical therapy with all CT angiographic findings confirmed. There were no injuries subsequently identified in the subgroup with a negative result at CT angiography. Of the 864 vascular divisions in which attenuation was measured, 69 (8%) of 864 had a mean attenuation less than 150 HU. CONCLUSION Integration of lower extremity CT angiography into multiphasic whole-body trauma imaging is feasible, helps detect clinically relevant vascular injuries, and results in diagnostic image quality in the majority of patients.

Use of 64-Row Multidetector CT Angiography in Blunt and Penetrating Trauma of the Upper and Lower Extremities

Computed tomographic (CT) angiography is rapidly becoming the preferred imaging test for the initial evaluation of patients suspected to have arterial injuries after blunt and penetrating trauma to the extremities. The increasingly widespread use of 64-row multidetector CT technology offers considerable benefits in extremity CT angiography in the trauma setting. These include the ability to generate isotropic data sets of long vascular territories, with the acquisition performed in a short time (10 seconds or less). Isotropic voxels make CT a fully multiplanar modality, a capability that is particularly useful for evaluating tortuous vessels. Sixty-four-row multidetector CT angiography of the extremities has the ability to demonstrate a variety of vascular injuries such as occlusion, pseudoaneurysm, active extravasation, and intimal dissection. Radiologists should be aware of the various potential pitfalls and limitations of extremity CT angiography in evaluation of trauma patients suspected to have extremity vascular injuries, including inadequate arterial enhancement, motion artifact, inadequate positioning, and streak artifact. By demonstrating the extent, location, and type of injury, CT angiography aids in the decision-making process to determine the appropriate management for each injury in each patient.

Ovarian Malignant Germ Cell Tumors: Cellular Classification and Clinical and Imaging Features

Ovarian malignant germ cell tumors (OMGCTs) are heterogeneous tumors that are derived from the primitive germ cells of the embryonic gonad. OMGCTs are rare, accounting for about 2.6% of all ovarian malignancies, and typically manifest in adolescence, usually with abdominal pain, a palpable mass, and elevated serum tumor marker levels, which may serve as an adjunct in the initial diagnosis, monitoring during therapy, and posttreatment surveillance. Dysgerminoma, the most common malignant germ cell tumor, usually manifests as a solid mass. Immature teratomas manifest as a solid mass with scattered foci of fat and calcifications. Yolk sac tumors usually manifest as a mixed solid and cystic mass. Capsular rupture or the bright dot sign, a result of increased vascularity and the formation of small vascular aneurysms, may be present. Embryonal carcinomas and polyembryomas rarely manifest in a pure form and are more commonly part of a mixed germ cell tumor. Some OMGCTs have characteristic features that allow a diagnosis to be confidently made, whereas others have nonspecific features, which make them difficult to diagnose. However, imaging features, the patients age at presentation, and tumor markers may help establish a reasonable differential diagnosis. Malignant ovarian germ cell tumors spread in the same manner as epithelial ovarian neoplasms but are more likely to involve regional lymph nodes. Preoperative imaging may depict local extension, peritoneal disease, and distant metastases. Suspicious areas may be sampled during surgery. Because OMGCTs are almost always unilateral and are chemosensitive, fertility-sparing surgery is the standard of care.

Diagnostic Imaging in Nontraumatic Pediatric Head and Neck Emergencies

Evaluation of pediatric patients in the emergency setting is complicated by a limited history and physical examination, which often produce findings that overlap with multiple disease processes. Imaging therefore plays a critical role in achieving an accurate and timely diagnosis. Knowledge of the typical clinical and imaging manifestations of common pediatric head and neck emergencies and congenital abnormalities allows the interpreting radiologist to identify the primary cause of the condition as well as any associated complications that may warrant immediate surgical management. The specific imaging protocol depends on the patients clinical status. Radiography, ultrasonography, and contrast material-enhanced computed tomography all may be appropriate modalities for an initial examination. In especially difficult or complex cases, magnetic resonance imaging may offer additional detail with respect to the extent of disease.

Pelvic applications of MR-guided high intensity focused ultrasound

MR-guided high intensity focused ultrasound (MRg HIFU) is a novel method of tissue ablation that incorporates high energy focused ultrasound for tissue heating and necrosis within an MR scanner that provides simultaneous stereotactic tissue targeting and thermometry. To date, MRg HIFU has been used primarily to treat uterine fibroids, but many additional applications in the pelvis are in development. This article reviews the basic technology of MRg HIFU, and the use of MRg HIFU to treat uterine fibroids, adenomyosis, and prostate cancer.

Gestational trophoblastic disease: Clinical and imaging features

Gestational trophoblastic disease (GTD) is a spectrum of both benign and malignant gestational tumors, including hydatidiform mole (complete and partial), invasive mole, choriocarcinoma, placental site trophoblastic tumor, and epithelioid trophoblastic tumor. The latter four entities are referred to as gestational trophoblastic neoplasia (GTN). These conditions are aggressive with a propensity to widely metastasize. GTN can result in significant morbidity and mortality if left untreated. Early diagnosis of GTD is essential for prompt and successful management while preserving fertility. Initial diagnosis of GTD is based on a multifactorial approach consisting of clinical features, serial quantitative human chorionic gonadotropin (β-hCG) titers, and imaging findings. Ultrasonography (US) is the modality of choice for initial diagnosis of complete hydatidiform mole and can provide an invaluable means of local surveillance after treatment. The performance of US in diagnosing all molar pregnancies is surprisingly poor, predominantly due to the difficulty in differentiating partial hydatidiform mole from nonmolar abortion and retained products of conception. While GTN after a molar pregnancy is usually diagnosed with serial β-hCG titers, imaging plays an important role in evaluation of local extent of disease and systemic surveillance. Imaging also plays a crucial role in detection and management of complications, such as uterine and pulmonary arteriovenous fistulas. Familiarity with the pathogenesis, classification, imaging features, and treatment of these tumors can aid in radiologic diagnosis and guide appropriate management. ©RSNA, 2017.

Revised Atlanta Classification for Acute Pancreatitis: A Pictorial Essay

The 2012 revised Atlanta classification is an update of the original 1992 Atlanta classification, a standardized clinical and radiologic nomenclature for acute pancreatitis and associated complications based on research advances made over the past 2 decades. Acute pancreatitis is now divided into two distinct subtypes, necrotizing pancreatitis and interstitial edematous pancreatitis (IEP), based on the presence or absence of necrosis, respectively. The revised classification system also updates confusing and sometimes inaccurate terminology that was previously used to describe pancreatic and peripancreatic collections. As such, use of the terms acute pseudocyst and pancreatic abscess is now discouraged. Instead, four distinct collection subtypes are identified on the basis of the presence of pancreatic necrosis and time elapsed since the onset of pancreatitis. Acute peripancreatic fluid collections (APFCs) and pseudocysts occur in IEP and contain fluid only. Acute necrotic collections (ANCs) and walled-off necrosis (WON) occur only in patients with necrotizing pancreatitis and contain variable amounts of fluid and necrotic debris. APFCs and ANCs occur within 4 weeks of disease onset. After this time, APFCs or ANCs may either resolve or persist, developing a mature wall to become a pseudocyst or a WON, respectively. Any collection subtype may become infected and manifest as internal gas, though this occurs most commonly in necrotic collections. In this review, the authors present a practical image-rich guide to the revised Atlanta classification system, with the goal of fostering implementation of the revised system into radiology practice, thereby facilitating accurate communication among clinicians and reinforcing the radiologists role as a key member of a multidisciplinary team in treating patients with acute pancreatitis. (©)RSNA, 2016.

Radiological appearances of corpus luteum cysts and their imaging mimics.

PurposeTo review the radiological appearances of corpus luteum cysts and their imaging mimics.ConclusionCorpus luteum cysts are normal post-ovulatory structures seen in the ovaries through the second half of the menstrual cycle and the first trimester of pregnancy. The typical appearance, across all modalities, is of a 1- to 3-cm cyst with a thick crenulated vascularized wall. Occasionally, similar imaging findings may be seen with endometrioma, ectopic pregnancy, tuboovarian abscess, red degeneration of a fibroid, and ovarian neoplasia. In most cases, imaging findings are distinctive and allow for a confident and accurate diagnosis that provides reassurance for patients and referring physicians and avoids costly unnecessary follow-up.

Suprarenal retroperitoneal liposarcoma with intracaval tumor thrombus: an imaging mimic of adrenocortical carcinoma

We report a 57-year-old previously healthy man who presented with dull right upper quadrant pain, weight loss, fatigue, and night sweats. Computed tomography demonstrated a large, heterogeneously enhancing, soft tissue mass with no macroscopic fat above the right kidney with tumor thrombus extending into the inferior vena cava and right atrium. Positron Emission Tomography scanning demonstrated intense Fluorodeoxyglucose avidity in the primary tumor and tumor thrombus. The presumptive radiological diagnosis was adrenocortical carcinoma, but surgical pathology revealed a dedifferentiated liposarcoma. We conclude that suprarenal retroperitoneal liposarcoma should be included in the differential diagnosis for an apparent adrenal mass with venous invasion.

Direct magnetic resonance imaging-guided biopsy of the prostate: Lessons learned in establishing a regional referral center

MRI-targeted biopsy of the prostate appears to have the potential to reduce the high rates of underdiagnosis and overdiagnosis associated with the current diagnostic standard of transrectal ultrasound guided systematic biopsy. Direct or “in bore” MRI-guided biopsy is one of the three methods for MRI-targeted core needle sampling of suspicious, generally Pi-RADS 4 or 5, foci within the prostate, and our early experience suggests the approach demonstrates substantial utility and promise in the care of patients with prostate cancer. We performed direct MRI-guided biopsies in 50 patients within 19 months of establishing the first referral center for this service in our region. Our preliminary results indicate the service can be easily grown due to unmet demand, primarily in patients with a negative traditional systematic biopsy but with a concerning focus at MRI (30 of 50; 60%). Other applications include evaluation of patients who are on active surveillance (n=14; ten upgraded to higher Gleason score at MRI-guided biopsy), who are biopsy naïve (n=5; all positive at MRI-guided biopsy), or post focal therapy (n=1; positive for recurrent tumor at MRI-guided biopsy). With careful patient selection and technique, we have achieved a favorable overall positive biopsy rate of 73% (37 of 50), with 84% (31 of 37) positive biopsies demonstrating Gleason score 7 or greater disease. Large multicenter comparative trials will be required to determine the relative accuracy and appropriate utilization of direct MRI guided biopsy in the care pathway of patients with known or suspected prostate cancer.