Whole-Body Computed Tomography Using Low-Dose Biphasic Injection Protocol With Adaptive Statistical Iterative Reconstruction V: Assessment of Dose Reduction and Image Quality in Trauma Patients.

AIM: This study aimed to evaluate potential dose savings on a revised protocol for whole-body computed tomography and image quality after implementing Adaptive Statistical Iterative Reconstruction V (ASiR-V) algorism for trauma patients and compare it with routine protocol. MATERIALS AND METHODS: One hundred trauma patients were classified into 2 groups using 2 different scanning protocols. Group A (n = 50; age, 32.48 ± 8.09 years) underwent routine 3-phase protocol. Group B (n = 50; age, 35.94 ± 13.57 years) underwent biphasic injection protocol including unenhanced scan for the brain and cervical spines, followed by a 1-step acquisition of the thorax, abdomen, and pelvis. The ASiR-V level was kept at 50% for all examinations, and then studies were reconstructed at 0% ASiR-V level. Radiation dose, total acquisition time, and image count were compared between groups (A and B). Two radiologists independently graded image quality and artifacts between both groups and 2 ASiR-V levels (0 and 50%). RESULTS: The mean (±SD) dose-length product value for postcontrast scans in group A was 1602.3 ± 271.8 mGy · cm and higher when compared with group B (P < 0.001), which was 951.1 ± 359.6 mGy · cm. Biphasic injection protocol gave a dose reduction of 40.4% and reduced the total acquisition time by 11.4% and image count by 37.6%. There was no statistically significant difference between the image quality scores for both groups; however, group A scored higher grades (4.62 ± 0.56 and 4.56 ± 0.67). Similarly, the image quality scores for both ASiR-V levels in both groups were not significantly different. CONCLUSIONS: Biphasic computed tomography protocol reduced radiation dose with maintenance of diagnostic accuracy and image quality after implementing ASiR-V algorism.

Characterization of salivary gland tumours with diffusion tensor imaging.

OBJECTIVES: To characterize salivary glands tumours with diffusion tensor imaging. METHODS: This study was conducted upon 53 patients (aged 18-81 years: mean 37 years) with salivary gland tumours that underwent diffusion tensor imaging was obtained using a single-shot echoplanar imaging sequence with parallel imaging at 1.5 T scanner. 48 slices were obtained, with a thickness of 2.5 mm, with no gap and the total scan duration was 7-8 min. The fractional anisotropy (FA) and the mean diffusivity (MD) value of the salivary gland tumours was calculated and correlated with pathological findings. Image analysis was performed by one radiologist. The receiver operating characteristic curve was drawn to detect the cut-off point of FA and MD used to characterize salivary gland tumours. RESULTS: The mean FA and MD of malignant salivary gland tumours (n = 17) (0.41 ± 0.07 and 0.89 ± 0.15 × 10-3 mm2 s-1) was significantly different (p = 0.001) than that of benign tumours (n = 36) (0.19 ± 0.07 and 1.28 ± 0.42 × 10-3 mm2 s-1), respectively. Combined FA and MD used to differentiate malignant from benign tumours has an area under the curve (AUC) of 0.974, and an accuracy of 86%. There was a significant difference in FA between Warthin tumours and malignant tumours (p = 0.001). Selection FA of 0.35 to differentiate malignant tumours from Warthin tumours revealed AUC of 0.878 and an accuracy of 80%. There was a significant difference in FA and MD of malignant tumours and pleomorphic adenomas (p = 0.001). Combined FA and MD used to differentiate malignant tumours from pleomorphic adenomas revealed AUC of 0.993, and an accuracy of 93%. There was a significant difference in FA and MD of Warthin tumours and pleomorphic adenomas (p = 0.001). Combined FA and MD used to differentiate Warthin tumours from pleomorphic adenomas revealed AUC of 0.978, and an accuracy of 86%. CONCLUSIONS: Diffusion-weighed imaging is a promising non-invasive method and it may be useful for the characterization and differentiation of benign and malignant salivary gland tumours.

Three-Dimensional Constructive Interference in Steady State Sequences and Phase-Contrast Magnetic Resonance Imaging of Arrested Hydrocephalus.

OBJECTIVE: To evaluate the role of three-dimensional constructive interference in steady state (3D-CISS) sequences and phase-contrast magnetic resonance imaging (PC-MRI) in patients with arrested hydrocephalus. METHODS: A prospective study of 20 patients with arrested hydrocephalus was carried out. All patients underwent PC-MRI and 3D-CISS for assessment of the aqueduct. Axial (through-plane), sagittal (in-plane) PC-MRI, and sagittal 3D-CISS were applied to assess the cerebral aqueduct and the spontaneous third ventriculostomy if present. Aqueductal patency was graded using 3D-CISS and PC-MRI. Quantitative analysis of flow through the aqueduct was performed using PC-MRI. RESULTS: The causes of obstruction were aqueductal obstruction in 75% (n = 15), third ventricular obstruction in 5% (n = 1), and fourth ventricular obstruction in 20% (n = 4). The cause of arrest of hydrocephalus was spontaneous third ventriculostomy in 65% (n = 13), endoscopic third ventriculostomy in 10% (n = 2), and ventriculoperitoneal shunt in 5% (n = 1), and no cause could be detected in 20% of patients (n = 4). There is a positive correlation (r = 0.80) and moderate agreement (κ = 0.509) of grading with PC-MRI and 3D-CISS sequences. The mean peak systolic velocity of cerebrospinal fluid was 1.86 ± 2.48 cm/second, the stroke volume was 6.43 ± 13.81 µL/cycle, and the mean flow was 0.21 ± 0.32 mL/minute. CONCLUSIONS: We concluded that 3D-CISS and PC-MRI are noninvasive sequences for diagnosis of the level and cause of arrested hydrocephalus.