James A. Brink

RETROSPECTIVE ANALYSIS OF THE EFFECT OF CROSSING VESSELS ON SUCCESSFUL RETROGRADE ENDOPYELOTOMY OUTCOMES USING SPIRAL COMPUTERIZED TOMOGRAPHY ANGIOGRAPHY

PURPOSE Using spiral computerized tomography (CT) angiography, we sought to evaluate the incidence of a crossing vessel in a group of adults with primary ureteropelvic junction obstruction who had previously undergone successful retrograde endopyelotomy. MATERIALS AND METHODS A total of 16 patients who had undergone successful Acucise balloon incision endopyelotomy for ureteropelvic junction obstruction, all with followup greater than 2 years, underwent a spiral CT angiogram with intravenous contrast material to identify those with a crossing vessel. Contrast enhanced CT was performed with dual phase technique on a Somatom-Plus-S CT scanner using prototype software. After 180-degree linear interpolation of the projection data, transaxial images of the affected kidney were reconstructed. In addition, at the time of the study all patients completed analog followup pain scales and quality of life assessment questionnaires. RESULTS Among the 16 patients 6 (38%) had anterior or posterior crossing vessels based on spiral CT angiography. No patient had both types. By analog pain scale patients had 80% mean improvement in pain (range 63 to 100). CONCLUSIONS In our series nearly 40% of patients with anterior or posterior crossing vessels had a long-term (greater than 2 years) successful outcome with retrograde endopyelotomy. Endopyelotomy continues to be our initial mode of therapy among adults with primary ureteropelvic junction obstruction. In our opinion the adverse influence of the crossing vessel is not sufficient to justify the added expense of preoperative angiography, spinal CT or endoluminal ultrasound.

Spiral computed tomographic colonography: Determination of the central axis and digital unraveling of the colon

RATIONALE AND OBJECTIVES The authors developed and tested automated and semiautomated bowel-lumen tracking and colon-unraveling techniques for determining the central axis of the bowel. METHODS A computer-simulated gastrointestinal tract phantom was used to test the accuracy of an automated algorithm for central axis determination and bowel unraveling. Variations in cross-sectional features between straight and unraveled formats were compared in a canine bowel segment in vitro and a human colon in vivo by using spiral computed tomography. Three readers each performed three semiautomated evaluations. RESULTS Accuracy of the automated algorithm was confirmed by the high degree of correlation in the cross-sectional feature measurements (length error, < 1%). For the canine colon segment, accuracy of the semiautomated algorithm was confirmed by comparison with the automated tracing. For the human colon, readings were reproducible with 3.3% (+/- 1.9 standard deviation) mean variation in length. CONCLUSION An automated algorithm for central axis deterioration and unraveling the colon has been validated in a gastrointestinal tract phantom. A semiautomated algorithm has been shown to be reproducible and time-efficient.

Digital Subtraction versus Film-Screen Angiography for Detecting Acute Pulmonary Emboli: Evaluation in a Porcine Model☆

PURPOSE To compare the diagnostic performance of digital subtraction angiography (DSA) to that of film-screen angiography (FSA) for detecting acute pulmonary embolism (PE) in a porcine model. MATERIALS AND METHODS DSA and FSA were performed in 13 pigs before and after central venous administration of autologous emboli. Results were compared to findings at necropsy with use of ex vivo pulmonary angiography to guide pathologic sectioning. The sensitivity and predictive value of a positive case for detecting each embolus were computed for each pulmonary artery branch order and compared with use of 95% confidence intervals. Interobserver variability among three readers for individual PE detection was calculated. RESULTS Pathologic examination of the lungs revealed 100 total PEs (location by vessel order: 1st = 1, 2nd = 0, 3rd = 15, 4th = 32, > 5th = 52). On average, FSA review identified 72 (72%) emboli and DSA review, 65 (65%). There was no significant difference in sensitivity or predictive value of a positive case between DSA and FSA for detecting emboli (P > .05). There was similar agreement among readers for individual PE detection with DSA (mean, 84%) and FSA (mean, 80%). CONCLUSION The diagnostic performance of DSA is equivalent to that of FSA for detecting emboli in porcine PA branches. Interobserver agreement for individual PE detection is similar for both imaging techniques.

GI Tract Unraveling in Volumetric CT

Gastrointestinal (GI) tract examination with computed tomography (CT) is currently performed by slice-based visual inspection despite the volumetric nature of the problem. The entire abdomen may now be continuously scanned within a single breath-hold with spiral CT. The GI tract can be computationally extracted from spiral CT images, the lumen explicitly unraveled onto a plane, and colonoscopy virtually simulated via fly-through display. A semi-automatic approach was developed for fly-through and unraveling in vivo. Automation of this approach was investigated in numerical simulation. The techniques are promising for colon cancer screening.

CT of Cystic Renal Masses: Analysis of Diagnostic Performance and Interobserver Variation

OBJECTIVE Our objective was to assess the clinical usefulness and interobserver variability of the Bosniak classification scheme for characterizing a series of pathologically proven cystic renal lesions imaged with CT. MATERIALS AND METHODS Seventy pathologically proven cystic renal masses (38 benign, 32 malignant) in 46 patients were reviewed independently by three radiologists. The cystic masses were categorized by each reviewer according to both the Bosniak classification and the receiver operating characteristic (ROC) analysis. Both the individual results for each reader and the pooled results for all three readers were analyzed. Interobserver agreement and discordance in classifying lesions as Bosniak categories I-II or III-IV were assessed. RESULTS The distribution of the 70 lesions (based on the average of the three readers) was 22 Bosniak I (0% malignant), eight Bosniak II (13% malignant), 11 Bosniak III (45% malignant), and 29 Bosniak IV (90% malignant). All readers agreed on the Bosniak classification in 59%, or 41 of the 70 lesions (I, 17; II, one: III, four: and IV, 19). Eleven (16%) of the 70 lesions were classified as Bosniak I or II by one reader and as Bosniak III or IV by at least one other reader. The area under the curve for the pooled ROC analysis was calculated to be 0.957. Individual reader values ranged from 0.914 to 0.981. The sensitivities, specificities, and accuracies for the three readers ranged from 94% to 100%, 71% to 92%, and 84% to 93%. Assessment of interobserver variability by kappa analysis yielded scores of .571 and .477 for the Bosniak and ROC analyses, respectively. CONCLUSION Overall, the Bosniak classification scheme is useful for evaluating renal masses: however, interobserver variation in distinguishing. Bosniak II and Bosniak III lesions may present difficulties in recommending surgical versus conservative management.