CT-based ballistic wound path identification and trajectory analysis in anatomic ballistic phantoms.

PURPOSE: To evaluate the accuracy of computed tomography (CT)-based ballistic wound path identification in phantoms by determining the agreement between actual shooting angles and both trajectory angles measured with a picture archiving and communication system (PACS) angle tool and angles calculated from x, y, z coordinates of the entrance and exit points. MATERIALS AND METHODS: In this institutional review board-approved model study, two simulated legs were shot by a trained marksman from 50 yards at six clinometer-measured angles with a 0.30-06 rifle and then scanned at multidetector CT. Radiologists measured the wound path angles on paracoronal reformations by using a PACS angle tool. Observers determined the Cartesian coordinates of the entrance and exit points of the wound paths on axial CT images by using detailed instructions. Angles were calculated from these coordinates by using a computer arctangent function. Agreement between the angles was evaluated with Bland-Altman plots. Means, ranges, and standard deviations of the angles also were determined. RESULTS: Radiologists identified all six wound paths on the CT images. The PACS tool-based measured and coordinate-based calculated angles were within 5° of the shooting angles. Results indicated that in larger study populations, one can be 91% confident that future coordinate-based angle calculations will differ from the actual shooting angle by no more than 5° and 95% confident that PACS tool-based angle measurements will differ from the actual shooting angles by no more than 4.5°. One can be 95% confident that future coordinate-based angle calculations will differ from PACS angle measurements by no more than 4.02°. CONCLUSION: Study results demonstrated the feasibility of consistent wound path identification and the accuracy of trajectory angle determination in models with use of multidetector CT.

Virtual colonoscopy in the US Army: current utilization at the Walter Reed Army Medical Center.

Virtual colonoscopy (VC), also known as CT colonography, continues to gain momentum worldwide as a safe and accurate alternative to traditional optical colonoscopy (OC) for colorectal cancer (CRC) screening. Within the US Army medical system, VC has experienced sustained growth since the program's inception in 2003. Integral to the success of this screening program has been dedicated radiologists and clinical support staff, collaboration with gastroenterology and an active training program for radiologists. Increasing patient and physician acceptance of the VC program along with radiologist education will ensure continued penetration of this valuable screening tool into the US Army medical system.

Effect of computer-aided detection for CT colonography in a multireader, multicase trial.

PURPOSE: To assess the effect of using computer-aided detection (CAD) in second-read mode on readers' accuracy in interpreting computed tomographic (CT) colonographic images. MATERIALS AND METHODS: The contributing institutions performed the examinations under approval of their local institutional review board, with waiver of informed consent, for this HIPAA-compliant study. A cohort of 100 colonoscopy-proved cases was used: In 52 patients with findings positive for polyps, 74 polyps of 6 mm or larger were observed in 65 colonic segments; in 48 patients with findings negative for polyps, no polyps were found. Nineteen blinded readers interpreted each case at two different times, with and without the assistance of a commercial CAD system. The effect of CAD was assessed in segment-level and patient-level receiver operating characteristic (ROC) curve analyses. RESULTS: Thirteen (68%) of 19 readers demonstrated higher accuracy with CAD, as measured with the segment-level area under the ROC curve (AUC). The readers' average segment-level AUC with CAD (0.758) was significantly greater (P = .015) than the average AUC in the unassisted read (0.737). Readers' per-segment, per-patient, and per-polyp sensitivity for all polyps of 6 mm or larger was higher (P < .011, .007, .005, respectively) for readings with CAD compared with unassisted readings (0.517 versus 0.465, 0.521 versus 0.466, and 0.477 versus 0.422, respectively). Sensitivity for patients with at least one large polyp of 10 mm or larger was also higher (P < .047) with CAD than without (0.777 versus 0.743). Average reader sensitivity also improved with CAD by more than 0.08 for small adenomas. Use of CAD reduced specificity of readers by 0.025 (P = .05). CONCLUSION: Use of CAD resulted in a significant improvement in overall reader performance. CAD improves reader sensitivity when measured per segment, per patient, and per polyp for small polyps and adenomas and also reduces specificity by a small amount.