Visual survey of cancer dissemination: classic patterns on helical CT. Abdomen and pelvis.

Helical CT evaluation of the abdomen and pelvis can be challenging in the cancer patient. This pictorial essay illustrates the important sites of neoplastic dissemination in the abdomen and pelvis. We will emphasize the classic CT appearance of several selected sites and indicate, where appropriate, the primary lesions usually associated with each.

Three-dimensional volume-rendering CT angiography in vasculitis: spectrum of disease and clinical utility.

Spiral computed tomographic angiography (CTA) coupled with three-dimensional volume-rendering image processing is a less invasive alternative to conventional catheter angiography. The technique has been used successfully in a variety of vascular diseases. In this pictorial essay, we review the CTA findings in selected cases of vasculitis. Technical considerations and the potential clinical value of this method are discussed.

Visual survey of cancer dissemination: classic patterns on helical CT of the neck and thorax.

Important sites of metastasis from intrathoracic and extrathoracic primary neoplasms are depicted on helical CT of the neck and thorax. This pictorial essay reviews several of these key sites of dissemination. For each, we illustrate the typical or classic appearance on helical CT and note the commonly associated primary malignancies.

Neurofibromatosis type 1: a diagnostic mimicker at CT.

Neurofibromatosis type 1 (NF1) is the most common of the phakomatoses and has a variety of localized or, more frequently, systemic manifestations throughout the thorax, abdomen, pelvis, and extremities. Classic computed tomographic (CT) findings in NF1 with thoracic involvement include small, well-defined subcutaneous neurofibromas, focal thoracic scoliosis, posterior vertebral scalloping, enlarged neural foramina, and characteristic rib abnormalities due to bone dysplasia or erosion from adjacent neurofibromas. However, more atypical manifestations are occasionally seen, and magnetic resonance (MR) imaging can be useful in equivocal cases. NF1 with abdominopelvic involvement tends to arise in the retroperitoneal, mesenteric, and paraspinal regions; it may be quite extensive and therefore difficult to distinguish from adenopathy at CT. The multiplanar capabilities of MR imaging, particularly with T2 weighting, make this modality helpful in evaluating affected patients and making the diagnosis. The classic peripheral manifestations of NF1 include limb hemihypertrophy, pseudarthrosis, peripheral nerve neurofibromas, and subcutaneous common and plexiform neurofibromas. In some cases of NF1, imaging findings are inconclusive, and biopsy and subsequent pathologic analysis are required. Familiarity with the various manifestations of NF1 in different anatomic locations is important in making the diagnosis and optimizing postdiagnostic treatment.

Helical CT of the abdomen and pelvis: potential diagnostic pitfalls of arterial-phase imaging in the genitourinary tract.

Spiral computed tomography (CT) is the state of the art today in imaging many features of the genitourinary tract. The use of dual-phase CT imaging improves our ability to detect and stage a wide range of pathologies. However, imaging in the arterial phase has several potential pitfalls that can result in either overcalling or undercalling genitourinary pathology. This paper reviews some of the common pitfalls and presents strategies on how to avoid them.

Three-dimensional volume-rendered CT angiography of the renal arteries and veins: normal anatomy, variants, and clinical applications.

Three-dimensional volume-rendered computed tomographic (CT) angiography represents an increasingly important clinical tool that, in many institutions, is replacing conventional angiography in the depiction of normal vascular anatomy and the diagnosis of vascular disorders. Evaluation of conditions affecting the renal vasculature constitutes a major focus of volume-rendered CT angiography, which has documented utility for demonstrating both arterial and venous disease. Arterial disorders include renal artery stenosis, renal artery aneurysms, and dissection. Venous disorders include splenorenal shunts, thrombosis, and intravascular tumor extension. In addition, volume-rendered CT angiography accurately displays the normal and variant renal vascular anatomy, which is crucial to detect before surgery, especially partial nephrectomy and laparoscopic nephrectomy. CT angiography is also useful in the evaluation of the renal vasculature following renal transplantation. Familiarity with proper CT protocols and data acquisition techniques are crucial for accurate diagnosis.

Asymptomatic large main pulmonary artery thromboembolism with a low-probability ventilation-perfusion lung scan.

The incidence of the interpretation of low-probability lung scans in asymptomatic patients with large central pulmonary embolisms and the prognostic implication of the ventilation-perfusion scan appearance in this clinical setting is not documented.

Multidetector CT angiography in the evaluation of pancreatic carcinoma: preliminary observations.

Multidetector CT (MDCT) provides unparalleled capabilities for combining narrow scan collimation with rapid data acquisition protocols. When combined with CT angiographic techniques and 3D-volume rendering we are able to create unique displays for evaluating a range of clinical pathologies. In this pictorial review we present the potential advantages of using MDCT angiography for the evaluation of pancreatic cancer and its role in the accurate staging of these patients. The use of dual-phase CT scanning in both the arterial phase and portal phase is addressed with the role of 3D CT angiography clearly defined. Numerous case studies are presented to show the advantages of these techniques over simple axial CT imaging.

Tailored helical CT evaluation of acute abdomen.

Helical computed tomography (CT) allows rapid, cost-effective evaluation of patients with acute abdominal pain. Tailoring the examination to the working clinical diagnosis by optimizing constituent factors (eg, timing of acquisition, contrast material used, means and rate of contrast material administration, collimation, pitch) can markedly improve diagnostic accuracy. Rapid (>/=3 mL/sec) intravenous injection of contrast material is required for optimal assessment of acute pancreatitis, ischemic bowel, aortic aneurysm, and aortic dissection. Narrow collimation and small reconstruction intervals can help detect calculi in the biliary system and genitourinary tract. Tailored helical CT in patients with acute pyelonephritis usually involves several acquisitions through the kidneys during various phases of renal enhancement. In patients with suspected renal infarction, CT protocol must include an acquisition during the corticomedullary phase. Helical CT with 5-mm collimation through the lower abdomen and pelvis is used to evaluate patients with suspected diverticulitis. Use of both oral and intravenous contrast material can help localize small bowel perforation and characterize related complications. Tailored helical CT for assessment of abdominal hemorrhage consists of initial unenhanced CT followed by optional contrast material-enhanced CT. Clear communication between the radiologist, the patient, and the referring physician is essential for narrowing the differential diagnosis into a working diagnosis prior to helical CT.

Targeted helical CT of the acute abdomen: appendicitis, diverticulitis, and small bowel obstruction.

CT, especially helical CT, provides a fast and reliable modality for evaluation of the patient presenting with acute abdominal pain. Helical CT can provide an accurate diagnosis in the majority of patients and has found great utility in the evaluation of acute gastrointestinal emergencies, including acute appendicitis, diverticulitis, and small bowel obstruction. This article reviews proper helical CT technique, diagnostic imaging findings, and pitfalls of interpretation in evaluation of these acute abdominal disorders.

Renal lymphoma: CT patterns with emphasis on helical CT.

Renal lymphoma is most often seen in conjunction with multisystemic, disseminated lymphoma or as tumor recurrence. Renal lymphoma may also be seen in immunocompromised patients or, rarely, as primary disease. Computed tomography (CT) is the most sensitive, efficient, and comprehensive examination for evaluation of the kidneys in patients with suspected renal lymphoma. Helical CT in particular improves detection and characterization of lymphomatous renal involvement by optimizing contrast dynamics and data acquisition and is the current modality of choice for accurate staging of lymphoma. Typical CT patterns in renal lymphoma include single and multiple masses, invasion from contiguous retroperitoneal disease, perirenal disease, and diffuse renal infiltration. Atypical CT patterns may also be encountered and provide a diagnostic challenge. These include spontaneous hemorrhage, necrosis, heterogeneous attenuation, cystic transformation, and calcification. Solid renal masses including renal cell carcinoma and metastases are the most commonly encountered entities that mimic renal lymphoma at CT and require biopsy for definitive diagnosis. CT (particularly helical CT) is useful in the evaluation of patients with suspected renal lymphoma, and familiarity with the spectrum of findings in renal lymphoma is important for accurate diagnosis.

Imaging of thoracic aortic disease.

Computed tomography, magnetic resonance imaging, and transesophageal echocardiography represent the relatively noninvasive techniques available for imaging thoracic aortic disease, especially in the evaluation of aneurysms and dissections. The article discusses the technique and application of these modalities in the evaluation of thoracic aorta. Imaging appearances of the commonly encountered pathologies of the thoracic aorta are presented and discussed, and potential pitfalls of technique and diagnosis are addressed.

CT of epithelial ovarian tumors.

Ovarian cancer is the second most common gynecologic malignancy in the United States and causes more deaths than any other cancer of the female reproductive system. Approximately two-thirds of patients have tumors that have spread beyond the pelvis at the time of diagnosis. Ovarian tumors arise from the surface epithelium or mesothelium, germ cells, or the gonadal stroma. Epithelial ovarian tumors include serous, mucinous, endometrioid, clear cell, and undifferentiated tumors. In general, the likelihood of malignancy increases with increasing solid-tissue elements and thicker septa. Surgery is central to the management of ovarian cancer. At the initial exploratory laparotomy, surgicopathologic staging and debulking of the tumor are undertaken. Patients with advanced cancer frequently undergo second-look surgery after chemotherapy to detect any residual disease. CT can provide staging information for preoperative planning and determination of surgical resectability, demonstrate tumor response to therapy, and allow detection of persistent or recurrent disease. However, a major limitation of CT is the lack of sensitivity for detection of small tumor implants, especially on the small intestine or mesentery. Dedicated CT of the pelvis is best performed with spiral CT. Ovarian carcinoma can spread by means of intraperitoneal implantation, lymphatic invasion, and hematogenous dissemination.

Postpartum complications in the abdomen and pelvis: CT evaluation.

Postpartum patients rarely develop complications that require radiologic evaluation. When indicated, CT can provide a rapid and reliable examination of the major pelvic organs and enable diagnosis of a multitude of postpartum complications, including abscesses, endometritis, thrombophlebitis, as well as more serious and potentially life-threatening sequelae of toxemia, DIC, and HELLP syndrome. This pictorial essay illustrates the utility of CT in the postpartum patient and demonstrates the spectrum of complications evaluated with CT.

Helical CT amniography of congenital diaphragmatic hernia.

OBJECTIVE: Accurate prenatal diagnosis of congenital diaphragmatic hernia is important for perinatal planning and potential fetal surgery. We describe the application and usefulness of helical CT amniography in the evaluation of suspected congenital diaphragmatic hernia in three fetuses. CONCLUSION: Helical CT amniography is an efficient means for evaluation of congenital diaphragmatic hernia. Accurate diagnosis was made in all three patients.