64-channel Multidetector Computed Tomography Research Articles

CT Fluoroscopy for Image-Guided Procedures: Physician Radiation Dose During Full-Rotation and Partial-Angle CT Scanning

PurposeTo determine physician radiation exposure when using partial-angle computed tomography (CT) fluoroscopy (PACT) vs conventional full-rotation CT and whether there is an optimal tube/detector position at which physician dose is minimized. Materials and MethodsPhysician radiation dose (entrance air kerma) was measured for full-rotation CT (360°) and PACT (240°) at all tube/detector positions using a human-mimicking phantom placed in a 64-channel multidetector CT. Parameters included 120 kV, 20- and 40-mm collimation, and 100 mA. The mean, standard deviation, and increase/decrease in physician dose compared with a full-rotation scan were reported. ResultsPhysician radiation exposure during CT fluoroscopy with PACT was highly dependent on the position of the tube/detector during scanning. The lowest PACT physician dose was when the physician was on the detector side (center view angle 116°; −35% decreased dose vs full-angle CT). The highest PACT physician dose was with the physician on the tube side (center view angle 298°; +34% increased dose vs full-angle CT), all doses P <.05 vs full-rotation CT. ConclusionsPartial-angle CT has the potential to both significantly increase or decrease physician radiation dose during CT fluoroscopy-guided procedures. The detector/tube position has a profound effect on physician dose. The lowest dose during PACT was achieved when the physician was located on the detector side (ie, distant from the tube). This data could be used to optimize CT fluoroscopy parameters to reduce physician radiation exposure for PACT-capable scanners.

Assessment of Filtered Back Projection, Adaptive Statistical, and Model-Based Iterative Reconstruction for Reduced Dose Abdominal Computed Tomography.

To compare standard of care and reduced dose (RD) abdominal computed tomography (CT) images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), model-based iterative reconstruction (MBIR) techniques. In an Institutional Review Board-approved, prospective clinical study, 28 patients (mean age 59 ± 13 years ), undergoing clinically indicated routine abdominal CT on a 64-channel multi-detector CT scanner, gave written informed consent for acquisition of an additional RD (<1 milli-Sievert) abdomen CT series. Sinogram data of RD series were reconstructed with FBP, ASIR, and MBIR and compared with FBP images of standard dose abdomen CT. Two radiologists performed randomized, independent, and blinded comparison for lesion detection, lesion margin, visibility of normal structures, and diagnostic confidence. Mean CT dose index volume was 10 ± 3.4 mGy and 1.3 ± 0.3 mGy for standard and RD CT, respectively. There were 73 "true positive" lesions detected on standard of care CT. Nine lesions (<8 mm in size) were missed on RD abdominal CT images which included liver lesions, liver cysts, kidney cysts, and paracolonic abscess. These lesions were missed regardless of patient size and types of iterative reconstruction techniques used for reconstruction of RD data sets. The visibility of lesion margin was suboptimal in (23/28) patients with RD FBP, (15/28) patients with RD ASIR, and (14/28) patients with RD MBIR compared to standard of care FBP images (P < 0.001). Diagnostic confidence for the assessment of lesions on RD images was suboptimal in most patients regardless of iterative reconstruction techniques. Clinically significant lesions (< 8 mm) can be missed on abdominal CT examinations acquired at a CT dose index volume of 1.3 mGy regardless of patients' size and reconstruction techniques (FBP, ASIR, and MBIR).

Multidetector Computed Tomography for the Evaluation of Coronary Artery Disease; The Diagnostic Accuracy in Calcified Coronary Arteries, Comparing with IVUS Imaging

PurposeContrast enhanced multidetector computed tomography (MDCT) has been used as an alternative to coronary angiography for the assessment of coronary artery disease in the patient of the intermediate risk group. However, coronary calcium is a known limiting factor for MDCT evaluation. We investigated the diagnostic accuracy of 64-channel MDCT with each coronary artery calcium score (CACS) by compared with intravascular ultrasound (IVUS) imaging.Materials and MethodsA total of 54 symptomatic patients with intermediate-risk (10 females, mean age 59.9±6.9 years, Framingham point scores 9-20) with 162 sites who had a culprit lesion on 64-channel MDCT before performing coronary angiography with IVUS were enrolled. Patients were divided into 4 subgroups depending on CACS: 0, 1-99, 100-399, and >400. Lesion length, external elastic membrane (EEM) cross sectional area (CSA), minimal luminal area, and plaque area were measured and compared between IVUS and MDCT.ResultsThe correlation coefficients for the measurements of the EEM CSA, lumen CSA, and plaque area were r=0.514, r=0.837, and r=0.578, respectively. Furthermore, there were close correlation of plaque area between four subgroups of CACS (r=0.671, r=0.623, r=0.562, r=0.571, respectively).ConclusionDespite the increase in CACS, the geometric analysis of coronary arteries using with 64-channel MDCT was comparable with IVUS in symptomatic patient of the intermediate risk group.

Perfusion CT in Colorectal Cancer: Comparison of Perfusion Parameters with Tumor Grade and Microvessel Density

ObjectiveThe purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC.Materials and MethodsPre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD.ResultsIn 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD.ConclusionBF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs.

Sixty-four MDCT achieves higher contrast in pancreas with optimization of scan time delay

To compare different multidetector computed tomography (MDCT) protocols to optimize pancreatic contrast enhancement. Forty consecutive patients underwent contrast-enhanced biphasic MDCT (arterial and portal-venous phase) using a 64-slice MDCT. In 20 patients, the scan protocol was adapted from a previously used 40-channel MDCT scanner with arterial phase scanning initiated 11.1 s after a threshold of 150 HU was reached in the descending aorta, using automatic bolus tracking (Protocol 1). The 11.1-s delay was changed to 15 s in the other 20 patients to reflect the shorter scanning times on the 64-channel MDCT compared to the previous 40-channel system (Protocol 2). HU values were measured in the head and tail of the pancreas in the arterial and portal-venous phase. Using an 11.1-s delay, 74.2 HU (head) were measured on average in the arterial phase and 111.2 HU (head) were measured using a 15-s delay (P < 0.0001). For the pancreatic tail, the average attenuation level was 76.73 HU (11.1 s) and 99.89 HU (15 s) respectively (P = 0.0002). HU values were also significantly higher in the portal-venous phase [pancreatic head: 70.5 HU (11.1 s) vs 84.0 HU (15 s) (P = 0.0014); pancreatic tail: 67.45 HU (11.1 s) and 77.18 HU (15 s) using Protocol 2 (P = 0.0071)]. Sixty-four MDCT may yield a higher contrast in pancreatic study with (appropriate) optimization of scan delay time.

Anatomical analysis of incidental left atrial diverticula in patients with suspected coronary artery disease using 64-channel multidetector CT

To describe and evaluate anatomical characterizations of incidental left atrial (LA) diverticula in patients with suspected coronary artery disease using 64-channel multidetector computed tomography (MDCT). From October 2008 to June 2009, 2059 patients with suspected coronary artery disease underwent electrocardiogram-gated 64-channel MDCT. Five hundred and thirty-two LA diverticula were identified in 377 patients (18.3%, male to female ratio: 216:161, mean age 59±10.89 years, range from 20 to 91 years). Two radiologists retrospectively analysed the number (single or multiple), size (diameter and length), shape (cystiform or tubiform), surface (smooth or irregular), and location (right or mid or left/upper or lower/lateral or posterior). If the length/diameter was <1.5, the diverticular shape was considered to be cystiform. Among 532 LA diverticula, single (270/532, 51.1%), cystiform (411/532, 77.3%), and smooth (332/532, 62.4%) diverticula were found. The right upper region (255/532, 47.9%) was the most common location, followed by the left lateral area (172/532, 32.3%). The average diameter was 4.7±2 mm (range from 1-19 mm), and the average length was 4.7±2.1 mm (range 1-13 mm). The average ratio of length to diameter was 1.15 (range 0.25-1.45). The average number of diverticula was 2±1.06 (range 1-5). Incidental LA diverticulum is not an uncommon finding in patients with suspected coronary artery disease. MDCT can provide anatomical details of LA diverticula. However, further studies are needed to determine their clinical significance.

Prospective Evaluation of the Accuracy of MDCT Angiography for Living Kidney Donor

PurposeIn donor nephrectomy, it is important to understand the exact anatomy of the blood vessels during minimally invasive surgery. We prospectively analyzed the accuracy of the vessel structures obtained by use of 64-row multi-detector computed tomography (MDCT) angiography compared with the actual vessel structure observed during surgery.Materials and MethodsWe analyzed 238 patients who underwent donor nephrectomy from July 2007 to August 2010. Before the operation, MDCT angiography was performed, and after the operation, the surgeons themselves wrote the protocol. The ipsilateral artery, the number of veins, the association with the run of the hilar vessel, and other vascular anomalies in computed tomography (CT) angiography and in the donor protocol were summarized.ResultsAmong 238 patients, nephrectomy was performed on the left side in 199 patients. The accuracy of MDCT for the artery and the vein was 93.3% and 92.4%, respectively. Accuracy did not differ significantly on the left and right sides (artery: p=0.124; vein: p=0.174). In 199 patients, the CT findings for the lumbar vein were compared with the surgical findings. The overall accuracy was shown to be 84.9%, and the accuracy of the group drained to the inferior vena cava (54%) was significantly different (p<0.01) from that of the group drained to the renal vein (98.6%). Thus, it may be necessary to pay close attention to the interpretation of the findings for the lumbar vein.ConclusionsMDCT angiography is important for understanding the exact anatomy of blood vessels before minimally invasive surgery. We showed that 64-channel MDCT has high accuracy in the main vessel and hilar vessels. However, close attention to the interpretation of the CT findings for the lumbar vein may be required.

Origem Anômala da Coronária (ALCAPA) em tomógrafo de 64 canais

Multidetector computed tomography (MDCT) with 64 channels provides to clinical practice an excellent method to detect coronary artery anomalies. The diagnosis of coronary anomalies consisting of origin of left coronary artery in the pulmonary trunk in adults with no history of congenital disease has few reports in literature. We report a case in a 30-year old female patient complaining of fatigue on major efforts and positive scintigraphy for ischemia. The diagnosis was made through 64-channel MDCT and thus it appears that the method can be used as baseline.

Optimal Multidetector Row CT Parameters for Evaluations of the Breast: A Phantom and Specimen Study

The use of breast computed tomography (CT) has been limited by radiation hazard and image quality. The objective of this study was to compare radiation doses and image quality for different 64-channel multidetector row CT (MDCT) parameters, and to potentially provide optimal CT parameters for breast imaging. For assessment of radiation doses, CT dose index (CTDI(100)) values were obtained at various x-ray tube voltages (80, 120, 140 kVp) and currents (30, 50, 100, 150, 200 mAs) using a standard CT body dose phantom. To evaluate image quality, four fresh mastectomy specimens were scanned and three radiologists graded images for overall image quality, glandular tissue-fat conspicuity, and Cooper's ligament sharpness. Statistically, linear regression analyses and multiple comparisons were used for investigation of the relationship between radiation dose, image qualities, and CT parameters. CTDI(100) values of < or =6 mGy were obtained at 80 kVp and any mAs, 120 kVp and 30 or 50 mAs, and 140 kVp and 30 or 50 mAs. Image quality at 80 kVp and 200 mAs, 120 kV and 50, 100, 150, or 200 mAs, and 140 kVp and all mAs values tested were significantly superior to those at 80 kVp and 30, 50, 100, or 150 mAs and 120 kV and 30 mAs (P < .05). Based on our results, 80 kVp and 200 mAs, 120 kVp and 50 mAs, 140 kVp and 30 mAs, or 140 kVp and 50 mAs can be used for breast MDCT scanning to reduce radiation dose and preserve image quality and 140 kVp at 30 mAs is the optimal setting.

Detection of Vascular Injuries in Patients with Blunt Pelvic Trauma by Using 64-Channel Multidetector CT

Vascular injuries are a major source of morbidity and mortality in patients with blunt pelvic trauma. Digital subtraction angiography (DSA) has traditionally been used to detect pelvic arterial injuries and to treat active arterial hemorrhage. Improvements in the technology of computed tomography (CT) have facilitated the implementation of CT angiography, which is beginning to replace DSA in the evaluation of patients with acute trauma. Pelvic CT angiography can reliably depict various pelvic arterial injuries and can help differentiate arterial hemorrhage from venous hemorrhage on the basis of multiphasic acquisitions, a method that may be used to tailor the subsequent clinical approach. With the use of a 64-channel multidetector CT scanner, multiphasic pelvic CT angiography can be integrated into the evaluation of trauma patients by using 1.25-mm reconstructed section thickness, pitch of 1:0.987, and gantry revolution time of 0.5 second to achieve near-isotropic results. A standard dose of 100 mL intravenous contrast material is injected at a rate of 5 mL/sec, and 30 mL saline solution, also at 5 mL/sec, is injected as a "chasing" bolus to follow the contrast material.

Evaluation of Biliary Abnormalities with 64-Channel Multidetector CT

Precise preoperative assessment of the vascular and biliary anatomy is important in ensuring the safety of hepatobiliary surgical procedures, including laparoscopic cholecystectomy, living donor liver transplantation, and tumor resection of the liver. Endoscopic retrograde cholangiography and percutaneous transhepatic cholangiography clearly depict the biliary anatomy but are considered invasive procedures. Magnetic resonance cholangiopancreatography is noninvasive but sometimes fails to depict the normal intrahepatic bile ducts. Multidetector computed tomography (CT) has contributed greatly to the evaluation of the normal anatomy, anatomic variants, and disease extent in this setting. With 64-channel multidetector CT, high-resolution three-dimensional images can be reconstructed from isotropic data with a 0.625-mm section thickness. Because of its capacity for thin-section scanning and multiplanar reformation, 64-channel multidetector CT cholangiography can clearly demonstrate the biliary anatomy, a variety of anatomic variants, and the extent of disease--information that is indispensable for successful hepatobiliary surgery.

Automated Segmentation and Morphometric Analysis of the Human Airway Tree from Multidetector CT Images

Remarkable advances in computed tomography (CT) technology geared our research toward investigating the integrative function of the lung and the development of a database of the airway tree incorporating anatomical and functional data with computational models. As part of this project, we are developing the algorithm to construct an anatomically realistic geometric model of airways from CT images. The basic concept of the algorithm is to segment as many airway trees as possible from CT images and later correct quantified parameters based on CT values. CT images are acquired with a 64-channel multidetector CT, and the airway is then extracted from them by the region-growing method while maintaining connectivity. Using this method, we extracted 428 airways up to the 14th branching generation. Although the airway diameters up to the 4th generation showed good agreement with those reported in an autopsy study, those in later generations were all greater than the reported values because of the limited resolution of the CT images. We corrected the errors in diameters by assessing the relationship between the diameter and median value of Hounsfield unit (HU) intensity of each airway; consequently, the diameters up to generation 8 agreed well with the reported values. Based on these results, we conclude that the use of HU-based correction algorithm combined with rough segmentation can be another way to improve data accuracy in the morphometric analysis of airways from CTs.