Double Dose Reduction in the Equilibrium Phase of Chest-Pelvic CT With Low Tube Voltage and Forward-Projected Model-Based Iterative Reconstruction Solution.

Objectives This study aimed to examine whether a new imaging method (80-kV forward-projected model-based iterative reconstruction solution [FIRST] protocol) that uses a combination of low tube voltage and FIRST can reduce radiation dose and contrast medium volume by comparing the quality of the resulting image with that of the image obtained by 120-kV adaptive iterative dose reduction 3D protocol in the equilibrium phase of chest-pelvic computed tomography (CT). Subjects and methods Twenty-seven patients underwent CT by both protocols on different days. Two radiologists subjectively assessed image quality by scoring axial images for sharpness, contrast enhancement, noise, artifacts, and overall quality. The mean CT values, standard deviations, contrast-to-noise ratios, and signal-to-noise ratios in the liver, aorta, and erector spinae muscles were used for objective assessment. Radiation dose parameters included the CT dose index volume, dose-length product, effective dose, and size-specific dose estimate. Results were compared for different body mass index categories. Results The 80-kV FIRST protocol helped achieve mean reductions of 36.3%, 35.7%, and 36.6% in CT dose index volume, effective dose, and size-specific dose estimate, respectively (p < 0.01). Therefore, this protocol was regarded as comparable to the conventional protocol in image quality, except for visual sharpness. Conclusions The 80-kV FIRST protocol is capable of reducing radiation dose and contrast medium volume compared to the adaptive iterative dose reduction 3D protocol in the equilibrium phase of chest-pelvic CT.

Early diagnosis of pancreatic necrosis based on perfusion CT to predict the severity of acute pancreatitis.

BACKGROUND: Perfusion CT can diagnose pancreatic necrosis in early stage of severe acute pancreatitis, accurately. However, no study to date has examined whether early diagnosis of pancreatic necrosis is useful in predicting persistent organ failure (POF). METHODS: We performed a multi-center prospective observational cohort study to investigate whether perfusion CT can predict the development of POF in the early stage of AP, based on early diagnosis of the development of pancreatic necrosis (PN). From 2009 to 2012, we examined patients showing potential early signs of severe AP (n = 78) on admission. Diagnoses for the development of PN were made prospectively by on-site physicians on the admission based on perfusion CT (diagnosis 1). Blinded retrospective reviews were performed by radiologists A and B, having 8 and 13 years of experience as radiologists (diagnosis 2 and 3), respectively. Positive diagnosis for the development of PN were assumed equivalent to positive predictions for the development of POF. We then calculated the area under the curve (AUC) of the receiver operating characteristic for POF predictions. RESULTS: Fourteen (17.9%) and 23 patients (29.5%) developed PN and POF, respectively. For diagnoses 1, 2, and 3, AUCs for POF predictions were 74, 68, and 73, respectively. CONCLUSIONS: Perfusion CT diagnoses pancreatic necrosis and on that basis predicts the development of POF; http://www.umin.ac.jp/ctr/index-j.htm,UMIN000001926 .

[Usefulness of Iterative Reconstruction Method in the Field of Acute Cerebral Infarction Computed Tomography Examination].

We evaluated clinical images to investigate the usefulness of adaptive iterative dose reduction algorithm (AIDR) in the field of acute cerebral infarction. We did receiver operating characteristic (ROC) analysis by 4 radiologists using 50 clinical images (abnormal case=24, normal case=26) which were reconstructed by AIDR and filtered back projection (FBP). The area under the curve (AUC) value from average ROC curve of observers were 0.79 with the FBP and 0.87 with the AIDR (P=0.31). The standard deviation of AUC was 0.06 with the FBP and 0.03 with the AIDR. More in detail, the AUC value of Expert group (over 10 years of experience) increased to 0.06 by using AIDR compared with FBP method. On the other hand, in Beginner group (less than 10 years of experience) there was 0.09 increase. Therefore, there was some possibility to reduce the variation of diagnostic accuracy among observer and the diagnostic accuracy improvement of the doctor in a few Experience group, by using AIDR for acute cerebral infarction computed tomography (CT) examination.

Continuous imaging of esophagogastric junction in patients with reflux esophagitis using 320-row area detector CT: a feasibility study.

BACKGROUND AND AIM: The function of the lower esophageal sphincter (LES) is evaluated using an esophageal manometric study. However, information regarding the surrounding organs is difficult to obtain with use of a sensor catheter. We investigated the utility of 320-row area detector computed tomography (CT) to evaluate morphological changes of the esophagogastric junction and surrounding organs. METHODS: The study subjects were 18 healthy volunteers and 29 patients with reflux esophagitis (RE). Immediately after swallowing a diluted contrast agent, continuous imaging of the esophagogastric junctional area was performed for 15 s. Using CT images, the presence or absence of esophageal hiatal hernia, His angle before and after swallowing, size of the diaphragmatic hiatus, morphologically identified-LES (MI-LES) length, intraluminal horizontal area of MI-LES during relaxation phase, MI-LES thickness, abdominal esophagus length, subcutaneous fat area, visceral fat area, and esophagogastric junction fat area were evaluated. RESULTS: Analysis of CT images showed more frequent occurrence of hiatal hernia, greater His angle, and a larger diaphragmatic hiatus in patients with severe RE, while the lengths of MI-LES and abdominal esophagus were shorter in those patients. Visceral and esophagogastric junction fat areas tended to be greater in patients with RE. In all subjects, the posterior wall of the MI-LES was thicker than the anterior wall. CONCLUSION: Continuous imaging with 320-row area detector CT is useful to evaluate morphological changes in the esophagogastric junction area in both normal individuals and patients with reflux esophagitis.