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.

Bronchial dehiscence after lung transplantation: correlation of CT findings with clinical outcome.

PURPOSE: To determine whether computed tomography (CT) can help predict which patients will require surgical or bronchoscopic intervention during healing of bronchial anastomotic dehiscence after lung transplantation. MATERIALS AND METHODS: The authors followed up 25 bronchoscopically proved dehiscent anastomoses through healing in 19 patients who underwent lung transplantation. CT findings were correlated with bronchoscopic results and clinical outcome. RESULTS: A bronchial defect and extraluminal air were initially present at CT in all 25 dehiscent anastomoses. Of 12 bronchial defects less than or equal to 4 mm, only one required intervention during healing (P < .05). Of 12 bronchial defects greater than 4 mm, six required intervention during healing. Eight of nine dehiscences with a tiny or small amount of extraluminal air healed with conservative treatment. Of 16 dehiscences associated with a moderate to large amount of extraluminal air, nine were treated conservatively and six required therapeutic intervention. Three healing anastomoses required bronchial stent placement. One patient died in the perioperative period. CONCLUSION: In patients with small dehiscences ( < 4mm) and patients with a tiny or small amount of extraluminal air, the anastomosis tends to heal without sequela. When patients have larger amounts of extraluminal air or larger ( > 4mm) dehiscences at presentation, CT cannot help predict which patients will require intervention.

Longitudinal image deblurring in spiral CT.

PURPOSE: To assess the feasibility of digital deconvolution techniques to improve longitudinal resolution of spiral computed tomography (CT) multiplanar reformations and evaluate how technical factors in deconvolution affect longitudinal resolution, noise, and edge ringing. MATERIALS AND METHODS: Longitudinal line spread function (LSF) of the system was estimated from longitudinal reformations of transaxial spiral CT images of a step test phantom. By using the estimated LSF, longitudinal reformations of the phantom and three clinical spiral CT studies were deconvolved by the methods of Wiener filtering and constrained iterative deconvolution. Edge ringing and image noise were quantified for Wiener filtering and constrained iterative deconvolution. RESULTS: Longitudinal reformations were substantially deblurred and resolution improved after deconvolution. Anatomic boundaries in clinical images were more clearly delineated after restoration. The methods of Wiener deconvolution and constrained iterative deconvolution improved the sharpness of the phantom step boundary at the expense of increased edge ringing and image noise. CONCLUSION: In longitudinal spiral CT reformations, blurring along the longitudinal axis can be reduced by Wiener filtering or constrained iterative deconvolution.

Massive ascites and pleural effusions associated with endometriosis.

We report a case of the unusual presentation of endometriosis causing ascites and pleural effusions subsequently confirmed at laparoscopy. This uncommon occurrence should be considered in a woman of childbearing age with appropriate clinical history, massive ascites, and cystic pelvic masses.

Helical CT: principles and technical considerations.

The performance of helical CT requires several user-defined parameters that exceed the requirements of conventional CT. One needs to carefully select the collimation, table increment, and reconstruction interval. Minimizing these parameters maximizes longitudinal resolution but with various trade-offs. Decreasing the collimation decreases the effective section thickness but increases pixel noise. Limiting the table increment to a pitch of 1 limits the broadening of the effective section thickness associated with the helical technique but also limits the coverage that can be achieved with a given helical scan. Our general practice is to minimize the collimation to cover the volume of interest and to accept a pitch up to 2, provided that we are using 180 degree interpolation. The reconstruction interval is also minimized to maximize longitudinal resolution but with trade-offs of increased image processing time, data storage requirements, and physician time for image review. For routine diagnosis, we recommend reconstruction of one to two sections per table increment, and, for multiplanar and three-dimensional imaging, we recommend at least three sections be reconstructed per table increment. The scan duration is dictated by both patient and machine factors.

Nuclear cystography and renal sonography: findings in girls with urinary tract infection.

This retrospective study documents the findings on nuclear cystography and renal sonography of 455 girls who had urologic imaging for a proved urinary tract infection (UTI). Nuclear cystograms were normal in 313 (69%) of 455 patients. Vesicoureteral reflux was seen in 142 patients (31%): six with grade I, 90 with grade II, 43 with grade III, and three with grade IV. Twelve percent of patients with vesicoureteral reflux had renal parenchymal scars. Increasing grades of reflux were associated with an increase in the severity and number of parenchymal scars. Normal renal sonograms were seen in 83% of patients. Abnormalities noted on sonograms included parenchymal scarring in 31 (7%) of the 455 patients, anomalies in 19 patients (4%), mild to moderate dilatation of the renal pelvis and or ureters in 45 patients (10%), and bladder wall thickening in 45 patients (10%).