Search

Objective: During computed tomography interpretation, some anatomical regions are optimally displayed in planes other than axial. The purpose of this review was to define best interpretative practice, by demonstrating through literature review and case demonstration the computed tomography applications that should routinely include multiplanar viewing of the volume., Conclusions: Owing to multidetector-row computed tomography technology, multiplanar reconstructions not only have become realistic and reliable but also, in some clinical settings, have been shown to improve diagnostic accuracy and interpretation speed.

Objective: Renal calculi are sometimes incidentally detected on contrast-enhanced computed tomography (CT) scans. The purpose of this study was to evaluate the detectability of renal calculi on arterial phase CT., Methods: One hundred thirty-three kidneys of 67 consecutive patients (one had prior unilateral nephrectomy) who underwent multidetector CT including noncontrast and arterial phase (acquired at 25 seconds from the start of 120 mL of intravenous contrast injection at a rate of 3 mL/s) scans were retrospectively evaluated. The detectability of renal calculi was determined by comparison of the noncontrast and contrast-enhanced scans., Results: Sixty-three calculi in 25 kidneys were detected in 17 patients on noncontrast CT. Forty-seven (75%) of the 63 calculi were also detected on the arterial phase scans. The size and highest attenuation of calculi (measured on noncontrast CT) detected on arterial phase scans were 4.3 +/- 3.0 mm and 556 +/- 353 Hounsfield units, and those detected only on noncontrast CT were 2.8 +/- 0.8 mm (P = 0.053) and 181 +/- 47 Hounsfield units (P < 0.0001), respectively. All calculi larger than 5 mm were detected on arterial phase scans., Conclusions: On arterial phase scans, 75% of the renal calculi and allrenal calculi larger than 5 mm were detected; the attenuation of the calculi had a significant correlation to detectability.

This report describes a case in which a lung transplant patient presented with lung masses. After an extensive medical workup and biopsy, the masses were found to be caused by metastatic glioblastoma multiforme, which the patient acquired from the lung donor. This article will also review similar cases in the literature.

Positive oral contrast agents (high-osmolar iodinated solutions [high-osmolar contrast medium] or barium sulfate suspensions) are used routinely for abdominal computed tomography. However, these agents are not ideal. Patients complain about the taste and, sometimes, refuse to drink the required quantity. Nausea, vomiting, and diarrhea are frequent. In certain clinical indications, either barium suspensions or high-osmolar contrast mediums may be contraindicated. This technical note describes the potential advantages of using low-osmolar iodinated solutions as an oral contrast agent for computed tomography.

Purpose: To determine acquisition protocol parameters currently used by different institutions for appendiceal multidetector computed tomography (MDCT)., Materials and Methods: A survey inquiring about multiple MDCT protocols was mailed to 99 fellows of the Society of Computed Body Tomography in August of 2004, with a second mailing sent in May 2005. A total of 46 institutions or hospitals are represented by these Society of Computed Body Tomography fellows. Details pertaining to protocols for the most advanced MDCT scanner in the department were requested., Results: The overall survey response rate was 17 of 46 or 37%. Fifteen protocols using 16-MDCT for suspected appendicitis were collected and tabulated. Parameters that are similar across institutions include a nonfocused acquisition using oral and intravenous contrast. Detector configuration is even divided between submillimeter and greater than 1 mm, and the most common reconstruction section thickness is 5 mm., Conclusions: Contrast administration and anatomical coverage are quite consistent across this set of protocols. However, future appendiceal MDCT research will need to address the most efficacious detector row collimation, reconstruction section thickness and interval, and the diagnostic capacity of protocols implementing dose reduction measures.

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that typically arise in association with the muscularis propria of gastrointestinal (GI) tract wall. They occur most frequently in the stomach (60%) but also can occur in the small bowel (30%) or elsewhere, including the colon and rectum (5%) and esophagus (<5%). In addition, a GIST may occur as a primary tumor of the omentum, mesentery, or retroperitoneum. They account for 1%-3% of gastric neoplasms, 20% of small bowel tumors, and 0.2%-1% of colorectal tumors. These tumors arise pathologically from the wall of the GI tract and can be characterized as benign, borderline, or with low or high malignant potential based on the pathologic appearance. Computed tomography (CT) plays an important role for the diagnosis and staging of these neoplasms because it can identify the tumor and assess for local spread or distant metastases. This article reviews the role of CT in the detection and characterization of GISTs. The optimal CT technique for visualization of small bowel tumors is reviewed, and a variety of GISTs are illustrated. Pathologic correlation is also included.

Although medical literature and differential diagnoses discussions tend to be organ specific, systemic diseases more commonly manifest with multi-organ involvement. Detection of dual organ involvement combined with clinical history narrows the differential to provide a more specific diagnosis. Two organs closely linked are the liver and the spleen. Many processes affect both of these organs through their common denominator, the reticuloendothelial system (RES). This pictorial essay reviews the wide spectrum of benign and malignant pathologies to be considered when computed tomography (CT) demonstrates concurrent focal disease in the liver and spleen.

Excretory phase computed tomography (CT) urography obtained with a 16-slice multidetector CT scanner using thin-section images (slice thickness = 0.75 mm, reconstruction increment = 0.5 mm) combined with interactive reformatted and 3-dimensional reconstruction techniques, high spatial resolution images of the urinary tract similar to those of classic intravenous urography can be produced. The purpose of this pictorial essay is to review the early experience of the authors and to show the wide range of abnormalities of the urinary tract detected with this technique.

The diagnosis of small bowel neoplasms can present a difficult challenge to the radiologist because the tumors are uncommon, often small, and may be difficult to detect radiographically. The most common small bowel neoplasms include adenocarcinoma, carcinoid, lymphoma, and gastrointestinal stromal tumors. The location and computed tomography (CT) appearance of the small bowel tumors may aid in the diagnosis. For instance, small bowel adenocarcinoma occurs more frequently in the duodenum and may result in obstruction. Carcinoid tumors are more common in the ileum and are typically hypervascular submucosal masses that produce a characteristic mesenteric mass when they spread to the mesenteric nodes. Lymphoma can occur anywhere along the gastrointestinal tract and have a variable CT appearance. It may appear as a single mass, multiple masses, an infiltrating lesion resulting in aneurysmal dilatation of the bowel, or as an exophytic mass. Gastrointestinal stromal tumors are more common in the jejunum and ileum and usually appear exophytic and bulky often with ulceration. Traditionally, small bowel series and enteroclysis have been used for imaging patients with suspected small bowel tumors. More recently, CT is beginning to play a more important role for this clinical indication. The thinner collimation possible with multidetector CT (MDCT) along with water as oral contrast and a good intravenous contrast bolus may improve the sensitivity of CT for detecting small bowel tumors. In addition, MDCT scanners improve the quality of the 3-dimensional CT (3D CT) images that are valuable to the clinicians and surgeons for surgical planning. It is important for the radiologist to be familiar with the CT appearance of these neoplasms and the potential role of MDCT and 3D imaging in their diagnosis and surgical planning.

The objective of this study was to measure the interobserver and interscan variation of coronary artery calcium scores using multidetector-row computed tomography (MDCT). Seventy-five patients underwent 2 sequential MDCT scans for coronary artery calcification. Each patient's score was separately measured by 3-blinded radiologists. Scores were treated as discrete and continuous data, and independent statistical analysis was performed on all results. There was a high proportion of interscan and inter-reader concordance for the presence of coronary calcium (range, 0.893-0.973) and for its quantity (range, 0.936-0.988). Overall, prospectively triggered multidetector-row calcium scoring is reproducible though there is more variation in those patients with already high scores. There is no need to scan patients twice at the same sitting.

Volume rendering, a postprocessing computer algorithm that creates three-dimensional (3D) displays from computed tomography (CT) datasets, can create 3D cholangiographic images (volume-rendered cholangiopancreatography, or VRCP) from intravenous contrast-enhanced abdominal CT datasets without the use of a biliary contrast agent. This article illustrates the utility of VRCP in the setting of biliary obstruction due to pancreatic cancer. The 3D renderings of the intra- and extrahepatic biliary tree provide valuable information for planning biliary drainage, including the location and length of the obstruction as well as the relationship of intrahepatic ducts to liver metastases.

Purpose: To determine the sensitivity, specificity, and accuracy of multidetector-row computed tomography (CT) using thin sections and multiplanar reconstruction for the detection of peritoneal implants in patients with ovarian cancer., Method: Seventeen thin section dual-phase multidetector-row CT scans were performed on 17 women with potential peritoneal metastases from ovarian cancer, which scans were then followed by surgery. Axial and multiplanar images from the CT scans were reviewed by 2 observers, and the results were compared with the operative and clinical notes., Results: Peritoneal metastases were detected by both readers in all 7 patients presenting with ovarian cancer and disease at laparotomy. Metastases were detected in 5/6 patients with recurrent tumor by observer 1 and in 4/6 patients by observer 2. Sensitivity, specificity, and accuracy for detecting peritoneal metastases at individual sites in the abdomen and pelvis were improved when both axial and multiplanar images were reviewed. Sensitivities were highest for the paracolic gutters and infracolic omentum (>70%). Approximately 50% of liver and diaphragmatic lesions were detected. Specificities approached 100% for all sites and accuracies were >80% for most sites of disease., Conclusion: The sensitivity, specificity, and accuracy of CT for peritoneal metastases in patients is high using thin slices and axial and multiplanar review of the data.

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.

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.

Purpose: The purpose of this work was to determine normal contrast enhancement of the small bowel with biphasic spiral CT, using water as oral contrast agent., Method: Biphasic spiral CT was performed in 50 healthy patients undergoing evaluation as potential renal donors. All patients received 500 ml of water as oral contrast agent and 150 ml of Omnipaque 350 administered by mechanical injector at a rate of 3 ml/s. Dual phase CT of the abdomen was performed in each patient. Acquisition of early phase images began 30 s after the start of the intravenous injection, and portal phase images were obtained 60 s after initiation of the contrast agent injection. Attenuation measurements (in Hounsfield units) were obtained from the wall of the small bowel (duodenum, jejunum, ileum) in both the arterial and the portal phases., Results: During the arterial phase, the mean (95% confidence interval) attenuation of the duodenum, jejunum, and ileum was 120 (+/- 5), 119 (+/- 5), and 118 (+/- 5) HU, respectively. During the portal phase, the average attenuation of the duodenum, jejunum, and ileum was 111 (+/- 4), 111 (+/- 3), and 107 (+/- 3) HU, respectively. There was no statistically significant difference between the attenuation of the duodenum, jejunum, or ileum within either the arterial or the portal venous phases. There was a statistically significant difference in small bowel enhancement between the arterial and portal venous phases., Conclusion: There is no important variation in small bowel attenuation during the 30 and 60 s scanning phases. This study serves as a normal reference that may be helpful when spiral CT is used to evaluate ischemic bowel or inflammatory small bowel diseases.

This article reviews the CT imaging features of a variety of nonneoplastic conditions that affect the small bowel and stresses important distinctive patterns that may help distinguish specific entities. Various inflammatory conditions (Crohn disease, radiation enteritis, graft versus host disease, celiac disease, Whipple disease, eosinophilic gastroenteritis, Behçet disease) as well as infiltrative disorders (amyloidosis, lymphangiectasia) and infectious diseases (Mycobacterium avium intracellulare, cytomegalovirus, cryptosporidiosis) are reviewed, with key differential points emphasized. In addition, miscellaneous conditions such as ischemia, small bowel diverticulitis, and small bowel hemorrhage are discussed.

Purpose: Our purpose was to determine if patients with pseudomembranous colitis (PMC) requiring surgical intervention demonstrate radiographic features distinct from those of patients treated successfully with standard medical therapy., Method: The indications for a CT study and the imaging findings from 17 patients who required laparotomy with colon resection for PMC were retrospectively reviewed. The CT findings were compared with the findings from 17 control patients (matched by clinical presentation) with PMC who were treated medically and did not require surgical intervention., Results: None of the CT findings evaluated in this study were significantly different between the surgical and nonsurgical groups. The CT findings evaluated for the surgical and nonsurgical groups, respectively, were as follows: wall thickness of the colon: 17.8+/-6.6 and 16.9+/-3.9 mm; largest caliber of the colon: 6.8+/-1.6 and 6.1+/-1.2 cm; presence of the accordion sign: 52.9 and 70.6%; heterogeneous contrast enhancement pattern (target sign): 57.1 and 57.1%; pericolonic stranding: 82.4 and 88.2%; ascites: 70.6 and 58.8%; pleural effusion(s): 64.7 and 64.7%; and subcutaneous edema: 64.7 and 64.7%., Conclusion: Although none of the CT findings evaluated in this study was significantly different between the surgical and nonsurgical groups, CT was often the initial diagnostic modality in both groups. It is important for radiologists to recognize the CT appearance of PMC and suggest the diagnosis. However, patient triage may not be based solely on the CT findings.