Linear accuracy and reliability of volume data sets acquired by two CBCT-devices and an MSCT using virtual models: a comparative in-vitro study.

OBJECTIVE: To discriminate clinically relevant aberrance, the accuracy of linear measurements in three-dimensional (3D) reconstructed datasets was investigated. MATERIALS AND METHODS: Three partly edentulous human skulls were examined. Landmarks were defined prior to acquisition. Two CBCT-scanners and a Quad-slice CT-scanner were used. Actual distances were physically measured with calipers and defined as a reference. Subsequently, from digital DICOM datasets, 3D virtual models were generated using maximum intensity projections (MIPs). Linear measurements were performed by semi-automated image analysis. Virtual and analogue linear measurements were compared using repeated measurements in a mixed model (p ≤ 0.05). RESULTS: No significant difference was found among all of the digital measurements when compared to one another, whereas a significant difference was found in matched-pairs analysis between CBCT and calipers (p = 0.032). All digitally acquired data resulted in lower mean values compared to the measurements via calipers. A high level of inter-observer reliability was obtained in the digital measurements (inter-rater correlation = 0.988-0.993). CONCLUSIONS: The reconstructed datasets led to highly consistent values among linear measurements. Yielding sub-millimeter precision, these modalities are assumed to reflect reality in a clinically irrelevant altered manner. During data acquisition and evaluation, a maximum of precision must be achieved.

Gallstone obstruction at the proximal ileum in an elderly woman: CT findings.

We present the case of a 73 years old woman with intestinal obstruction caused by a rare cause of biliary ileus, who arrived at our emergency department with lower abdominal quadrants pain (since about 2 months), recently associated with nausea, vomiting and abdominal distension. After clinical and laboratory evaluations, a computed tomography (CT) scan without intravenous contrast medium administration was urgently requested. CT had shown the presence of a large gallstone (diameter of about 6 cms) at the proximal ileum (stopped in this tract after the passage through a biliary-enteric fistula), and another gallstone (diameter of about 2 cms) in the gallbladder, associated with concentric thickening of gallbladder's walls, gas in the biliary tree, obliteration of peri-gallbladder's fat density and fluid in the peri-subhepatic area. The patient had urgently a surgical treatment (videolaparoscopy). CT had a crucial role for the diagnosis of intestinal obstruction, for its high sensitivity and specificity. It is well able to provide the causes and the level of the obstruction, its extension and complications, thus orienting toward the best clinical management/outcome for the patient.