Multidetector computed tomography of acute vascular injury in blunt abdominal/pelvic trauma: imaging predictors of treatment.

PURPOSE: The purpose of this study was to analyze the multidetector computed tomography (MDCT) morphologic characteristics of non-aortic acute vascular injuries (AVI) in patients with blunt abdominopelvic trauma that predict treatment. METHODS: CT scans of 65 trauma patients with non-aortic AVI were reviewed. AVI morphology was categorized as linear or round. The organ of involvement, location of hemorrhage, initial size of hematoma, and hemodynamic status were recorded. Expansion rates of the hematoma were calculated in 40 patients who had delayed imaging. Multivariate regression was used to analyze the morphologic features of AVI and treatment. RESULTS: Patients with linear AVI were four times more likely to require aggressive treatment (surgery or embolization) than those with a round morphology, independent of the hemodynamic status. There was no main effect of the organ involved, location of hemorrhage, initial bleed size, or expansion rate on the probability of aggressive treatment. CONCLUSION: The location, initial size, and expansion rate of AVI are not significant predictors of aggressive treatment with surgery or embolization. Linear morphology of AVI, however, is more likely to require aggressive treatment than round AVI, independent of the hemodynamic status. Linear AVI likely reflects a spurting jet of active extravasation, whereas round AVI likely represents a pseudoaneurysm or slow bleed.

Multidetector-row helical CT and advanced postprocessing techniques for the evaluation of pancreatic neoplasms.

An important feature of multidetector-row helical computed tomography (CT) is the increased speed of scanning that permits routine use of very thin collimation and acquisition of near isometric imaging data of the abdomen within the time span of a single breath-hold. The parallel escalation in the capabilities of workstations makes feasible the practical use of advanced postprocessing techniques to create high quality volumetric imaging. This article highlights the unique contributions of multidetector-row CT and advanced postprocessing techniques to the evaluation of the pancreas and peripancreatic vascular structures and their value in the diagnosis and staging of pancreatic neoplasms.

Impact of multidetector CT hepatic arteriography on the planning of chemoembolization treatment of hepatocellular carcinoma.

OBJECTIVES: We examined the impact of the increased sensitivity for hypervascular masses of multidetector CT hepatic arteriography on treatment decisions involving selective chemoembolization of hepatocellular carcinomas. SUBJECTS AND METHODS: Thirty patients were referred for chemoembolization of unresectable hepatocellular carcinoma. Initial selective chemoembolization plans were formulated on the basis of diagnostic biphasic CT or MR imaging. Ultrafast CT hepatic arteriography was performed using a multidetector CT scanner and selective contrast material injection into the hepatic artery. The entire liver was scanned in a single breath-hold of approximately 20 sec with a slice thickness of 1 mm. Lesions and their arterial supplies were identified, and these data were immediately used to formulate a final plan for chemoembolization. RESULTS: Hypervascular masses were detected in 29 patients. In 16 (53%) of the patients, preprocedural CT or MR imaging underestimated the number of lesions. In nine (30%) of these 16 patients, the additional lesions were detected only on CT hepatic arteriography, not on conventional angiography. CT hepatic arteriography findings had a major impact on planning the way in which chemoembolization treatment was performed. In three of the nine patients, the previously undetected lesions were treated with additional superselective chemoembolization. In the other six patients, chemoembolization was performed less selectively than originally planned. CONCLUSION: Primarily because of the high sensitivity of multidetector CT hepatic arteriography in revealing small and multifocal hepatomas, findings of this modality frequently alter treatment plans involving selective administration of chemoembolic material.

Preoperative duplex ultrasonography evaluation for deep venous thrombosis in revision hip arthroplasty patients.

In a prospective consecutive series, 53 revision hip arthroplasties were performed in 51 patients. Pre- and postoperative Duplex ultrasonography examinations were reviewed by an independent, experienced radiologist. Three of 51 patients (53 procedures) had evidence of chronic deep venous thrombosis (DVT) or other venous abnormality preoperatively, yielding an incidence of 5.6%. One (1.9%) patient developed an acute DVT postoperatively despite pharmacological and mechanical preventative measures. These results indicate the use of preoperative ultrasonography as a screening tool prior to revision hip arthroplasty is not warranted based on the low incidence of acute or chronic DVT detected preoperatively. Long-term anticoagulation, when necessary, can be based on the findings of a postoperative scan.

Parathyroid crisis in a 20 year old--an unusual cause of hypercalcaemic crisis.

Since the advent of automated serum analysis, patients with primary hyperparathyroidism (PHPT) are often asymptomatic at presentation or have mild symptoms attributable to the disease. Parathyroid crisis is a rare and potentially fatal complication of PHPT in which patients develop severe hypercalcaemia with signs and symptoms of multiple organ dysfunction. A case of parathyroid crisis in a 20 year old man who presented with brown tumours and renal stones is described.

Imaging the patient with right upper quadrant pain.

A variety of high-resolution imaging techniques are currently available for the evaluation of patients with RUQ pain. In these patients, an imaging approach that is based on identifying the presence of certain clinical signs and symptoms can aid in choosing the appropriate imaging modality and establishing the diagnosis. For patients presenting with a positive Murphy sign, sonography and biliary scintigraphy are the most useful initial imaging techniques. In patients with fever and a negative Murphy sign, a combination of sonography and contrast-enhanced CT can establish the diagnosis in most cases. And finally, in patients without fever or a positive Murphy sign, CT and MR are appropriate first-line imaging techniques.

Intraoperative ultrasonography for localization of recurrent thyroid cancer.

Advances in measurement of thyroglobulin (Tg) and in imaging techniques including high resolution ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) scan have increased our ability to detect thyroid cancer recurrences at an earlier stage. (1,2) After thyroidectomy, patients are often treated with radioiodine, but the recurrent cancers may not image with radioiodine. In these instances, the only definitive treatment is surgical resection. Reoperative neck surgery can be challenging, especially when trying to find a small cancer nodule within the central neck that contains dense fibrotic scar tissue. Herein we describe the use of intraoperative ultrasonography to identify the location of recurrent thyroid cancer. This technique can aid in tumor localization and may help to avoid complications such as recurrent nerve injury.

Tissue harmonic imaging techniques: physical principles and clinical applications.

Tissue harmonic imaging (THI) is a new gray-scale sonographic technique that improves image clarity. Harmonics form within the insonated tissue as a consequence of nonlinear sound propagation. Imaging with endogenously formed harmonics means that the distorting layer of the body wall is traversed only once by the harmonic beam--during echo reception. Both image contrast and lateral resolution are improved in harmonic mode compared with conventional (fundamental mode) sonography. This article summarizes the physics and various implementations of harmonic imaging mode, and reviews the clinical applications that have emerged to date.

Ultrasonographically guided thyroid biopsy: a review with emphasis on technique.

We describe our technique for ultrasonographically guided fine-needle aspiration biopsy of the thyroid that achieves a high rate of diagnostic specimens. Indications for ultrasonographically guided fine-needle aspiration biopsy included a difficult-to-palpate thyroid nodule and previously unsuccessful palpation-guided fine-needle aspiration. Ultrasonographically guided fine-needle aspiration biopsy was performed on 316 thyroid nodules in 306 patients. Adequate cytologic specimens were obtained in 97.2% of the nodules in which biopsy was performed, with a 2.8% rate of inadequate cellularity. Two helpful aspects of this technique that were thought to improve the overall diagnostic yield were the use of color and power Doppler "vascular mapping" of the nodule just before biopsy and on-site cytologic control.

A statistical 3-D pattern processing method for computer-aided detection of polyps in CT colonography.

Adenomatous polyps in the colon are believed to be the precursor to colorectal carcinoma, the second leading cause of cancer deaths in United States. In this paper, we propose a new method for computer-aided detection of polyps in computed tomography (CT) colonography (virtual colonoscopy), a technique in which polyps are imaged along the wall of the air-inflated, cleansed colon with X-ray CT. Initial work with computer aided detection has shown high sensitivity, but at a cost of too many false positives. We present a statistical approach that uses support vector machines to distinguish the differentiating characteristics of polyps and healthy tissue, and uses this information for the classification of the new cases. One of the main contributions of the paper is the new three-dimensional pattern processing approach, called random orthogonal shape sections method, which combines the information from many random images to generate reliable signatures of shape. The input to the proposed system is a collection of volume data from candidate polyps obtained by a high-sensitivity, low-specificity system that we developed previously. The results of our ten-fold cross-validation experiments show that, on the average, the system increases the specificity from 0.19 (0.35) to 0.69 (0.74) at a sensitivity level of 1.0 (0.95).

Thickened submucosal layer: a sonographic sign of acute gastrointestinal abnormality representing submucosal edema or hemorrhage. 2000 ARRS Executive Council Award II. American Roentgen Ray Society.

OBJECTIVE: We correlated the sonographic appearance of bowel wall thickening with the acuity of the underlying disease process. SUBJECTS AND METHODS: Sonograms of thickened bowel walls were reviewed in 37 patients with proven gastrointestinal abnormalities. Sonographic findings were correlated with clinical presentation, endoscopy, histology, laboratory data, barium studies, and CT. RESULTS: Twenty-eight patients presented acutely, and nine patients had chronic or subacute disease processes. Two of the 28 patients had concurrent acute and chronic processes. In 27 of 28 patients with acute processes, the abnormal bowel segments were characterized by an echogenic submucosal layer thicker than 2.5 mm. In contrast, nine patients with chronic or subacute processes had relatively uniform hypoechoic thickening of the bowel wall with loss of visualization of a discrete echogenic submucosal layer. CT was available for comparison in 30 of 37 patients. Of the 28 patients with acute abnormalities, the thickened echogenic submucosal layer on sonography corresponded to either low-attenuation submucosal edema (n = 25) or acute submucosal hemorrhage (n = 3). CONCLUSION: The finding of a thickened submucosal layer suggests an acute disease process of the bowel and corresponds to either submucosal edema or hemorrhage.

Automated polyp detector for CT colonography: feasibility study.

An abdominal computed tomographic scan was modified by inserting 10 simulated colonic polyps with use of methods that closely mimic the attenuation, noise, and polyp-colon wall interface of naturally occurring polyps. A shape-based polyp detector successfully located six of the 10 polyps. When settings that enhanced the edge profile of polyps were chosen, eight of 10 polyps were detected. There were no false-positive detections. Shape analysis is technically feasible and is a promising approach to automated polyp detection.

Focal liver lesions: pattern-based classification scheme for enhancement at arterial phase CT.

PURPOSE: To present our early experience with a classification scheme for categorizing focal liver lesions on the basis of the enhancement patterns that they exhibit in the arterial phase of computed tomography (CT) and to determine whether particular enhancement patterns suggest particular diagnoses. MATERIALS AND METHODS: The authors reviewed arterial phase CT images in 100 consecutive patients with focal liver lesions, excluding simple cysts. The enhancement pattern of the dominant or representative lesion in each patient was classified into one of five categories-homogeneous, abnormal internal vessels or variegated, peripheral puddles, complete ring, or incomplete ring-by three radiologists blinded to the proved diagnosis. Lesions without enhancement were recorded separately. Agreement was reached by consensus in all cases. Standards of reference included findings at histologic examination, correlative imaging, or clinical and imaging follow-up. RESULTS: Ninety-two percent of the 100 lesions demonstrated arterial phase enhancement. Patterns associated with positive predictive values of 82% or greater and specificity of 80% or greater included abnormal internal vessels or variegated (hepatocellular carcinoma), peripheral puddles (hemangioma), and complete ring (metastasis). CONCLUSION: The appearance of hepatic lesions in the arterial phase of enhancement has potential use in the determination of specific diagnoses. The classification scheme used in this study may be a useful tool for the interpretation of arterial phase CT studies.

Visualization modes for CT colonography using cylindrical and planar map projections.

PURPOSE: The purpose of this study was to demonstrate the limitations to the effectiveness of CT colonography, colloquially called virtual colonoscopy (VC), for detecting polyps in the colon and to describe a new technique, map projection CT colonography using Mercator projection and stereographic projection, that overcomes these limitations. METHOD: In one experiment, data sets from nine patients undergoing CT colonography were analyzed to determine the percentage of the mucosal surface visible in various visualization modes as a function of field of view (FOV). In another experiment, 40 digitally synthesized polyps of various sizes (10, 7, 5, and 3.5 mm) were randomly inserted into four copies of one patient data set. Both Mercator and stereographic projections were used to visualize the surface of the colon of each data set. The sensitivity and positive predictive value (PPV) were calculated and compared with the results of an earlier study of visualization modes using the same CT colonography data. RESULTS: The percentage of mucosal surface visualized by VC increases with greater FOV but only approaches that of map projection VC (98.8%) at a distorting, very high FOV. For both readers and polyp sizes of > or =7 mm, sensitivity for Mercator projection (87.5%) and stereographic projection (82.5%) was significantly greater (p < 0.05) than for viewing axial slices (62.5%), and Mercator projection was significantly more sensitive than VC (67.5%). Mercator and stereographic projection had PPVs of 75.4 and 78.9%, respectively. CONCLUSION: The sensitivity of conventional CT colonography is limited by the percentage of the mucosal surface seen. Map projection CT colonography overcomes this problem and provides a more sensitive method with a high PPV for detecting polyps than other methods currently being investigated.

Aortic aneurysmal disease: assessment of stent-graft treatment-CT versus conventional angiography.

PURPOSE: To compare computed tomographic (CT) angiography and conventional angiography for determining the success of endoluminal stent-graft treatment of aortic aneurysms. MATERIALS AND METHODS: Forty patients underwent conventional angiography and CT angiography following treatment of aortoiliac aneurysms with endoluminal stent-grafts. Six additional sets of conventional angiographic-CT angiographic examinations were performed in five patients after placement of additional stent-grafts or coil embolization to treat perigraft leakage. Three faculty CT radiologists who were blinded to patient clinical data and outcome independently interpreted the CT angiograms, and three faculty angiographers, who were not involved in the stent-graft deployment, interpreted the conventional angiograms. Images were assessed for the presence of postdeployment complications. A reference standard was developed by experienced radiologists using all available images and clinical data. Sensitivities, specificities, and kappa values were calculated. RESULTS: Perigraft leakage was the most commonly identified complication. Twenty perigraft leaks were detected in the results of 46 examinations. Sensitivities and specificities for detecting perigraft leakage were 63% and 77% for conventional angiography and 92% and 90% for CT angiography, respectively. The kappa value was 0. 41 for conventional angiography and 0.81 for CT angiography. CONCLUSION: CT angiography is the preferred method for establishing the presence of perigraft leakage following treatment of aortoiliac aneurysms with stent-grafts.

Computed tomographic angiography: historical perspective and new state-of-the-art using multi detector-row helical computed tomography.

Since its clinical introduction in 1991, volumetric computed tomography scanning using spiral or helical scanners has resulted in a revolution for diagnostic imaging. In addition to new applications for computed tomography, such as computed tomographic angiography and the assessment of patients with renal colic, many routine applications such as the detection of lung and liver lesions have substantially improved. Helical computed tomographic technology has improved over the past eight years with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms, but the greatest advance has been the recent introduction of multi detector-row computed tomography scanners. These scanners provide similar scan quality at a speed gain of 3-6 times greater than single detector-row computed tomography scanners. This has a profound impact on the performance of computed tomography angiography, resulting in greater anatomic coverage, lower iodinated contrast doses, and higher spatial resolution scans than single detector-row systems.

Treatment and stabilization of complex wounds involving the pelvic bone, groin, and femur with the inferiorly based rectus abdominis musculocutaneous flap and the use of power color Doppler imaging in preoperative evaluation.

The authors present case reports demonstrating the trilevel utility of the inferiorly based rectus abdominis musculocutaneous flap in the closure of complex wounds involving the pelvis, groin, and femur that had failed previously or were not amenable to traditional closure techniques. The use of the rectus abdominis flap was especially advantageous for achieving infection eradication and large dead space closure. Additionally they present the emerging technique of power color Doppler imaging as a valuable tool in preoperative flap planning. This technique is particularly useful in evaluating the candidacy for rectus abdominis musculocutaneous flap placement of patients with a prior history of abdominal surgeries, trauma, infection, irradiation, or other conditions that might compromise the patency of the deep inferior epigastric vessels.