Conventional Multislice Computed Tomography Research Articles

Usefulness of the spectral shaping dual-source computed tomography imaging technique in posterior corrective fusion for adolescent idiopathic scoliosis.

Since childhood exposure to radiation has been demonstrated to increase cancer risk with increase in radiation dose, reduced radiation exposure during computed tomography (CT) evaluation is desired for adolescent idiopathic scoliosis (AIS). Therefore, this retrospective study aimed to investigate the radiation dose of dual-source CT using a spectral shaping technique and the accuracy of the thoracic pedicle screw (TPS) placement for posterior spinal fusion (PSF) in patients with AIS. Fifty-nine female patients with thoracic AIS who underwent PSF using CT-guided TPSs were included and divided into two groups comprised of 23 patients who underwent dual-source CT (DSCT) with a tin filter (DSCT group) and 36 who underwent conventional multislice CT (MSCT group). We assessed the CT radiation dose using the CT dose index (CTDIvol), effective dose (ED), and accuracy of TPS insertion according to the established Neo's classification. The DSCT and MSCT groups differed significantly (p < 0.001) in the mean CTDIvol (0.76 vs. 3.31mGy, respectively) and ED (0.77 vs. 3.47mSv, respectively). Although the correction rate of the main thoracic curve in the DSCT group was lower (65.7% vs. 71.2%) (p = 0.0126), the TPS accuracy (Grades 0-1) was similar in both groups (381 screws [88.8%] vs. 600 screws [88.4%], respectively) (p = 0.8133). No patient required replacement of malpositioned screws. Spectral shaping DSCT with a tube-based tin filter allowed a 75% radiation dose reduction while achieving TPS insertion accuracy similar to procedures based on conventional CT without spectral shaping.

Postoperative computed tomography imaging of pediatric patients with craniosynostosis: radiation dose and image quality comparison between multi-slice computed tomography and O-arm cone-beam computed tomography

BackgroundWhen postoperative multi-slice computed tomography (MSCT) imaging of patients with craniosynostosis is used, it is usually performed a few days after surgery in a radiology department. This requires additional anesthesia for the patient. Recently, intraoperative mobile cone-beam CT (CBCT) devices have gained popularity for orthopedic and neurosurgical procedures, which allows postoperative CT imaging in the operating room.ObjectiveThis single-center retrospective study compared radiation dose and image quality of postoperative imaging performed using conventional MSCT scanners and O-arm CBCT.Materials and methodsA total of 104 pediatric syndromic and non-syndromic patients who were operated on because of single- or multiple-suture craniosynostosis were included in this study. The mean volumetric CT dose index (CTDIvol) and dose-length product (DLP) values of optimized craniosynostosis CT examinations (58 MSCT and 46 CBCT) were compared. Two surgeons evaluated the subjective image quality.ResultsCBCT resulted in significantly lower CTDIvol (up to 14%) and DLP (up to 33%) compared to MSCT. Multi-slice CT image quality was considered superior to CBCT scans. However, all scans were considered to be of sufficient quality for diagnosis.ConclusionThe O-arm device allowed for an immediate postoperative CBCT examination in the operating theater using the same anesthesia induction. Radiation exposure was lower in CBCT compared to MSCT scans, thus further encouraging the use of O-arms. Cone-beam CT imaging with an O-arm is a feasible method for postoperative craniosynostosis imaging, yielding less anesthesia to patients, lower health costs and the possibility to immediately evaluate results of the surgical operation.

COPD Imaging on a 3rd Generation Dual-Source CT: Acquisition of Paired Inspiratory-Expiratory Chest Scans at an Overall Reduced Radiation Risk.

As stated by the Fleischner Society, an additional computed tomography (CT) scan in expiration is beneficial in patients with chronic obstructive pulmonary disease (COPD). It was thus the aim of this study to evaluate the radiation risk of a state-of-the-art paired inspiratory-expiratory chest scan compared to inspiration-only examinations. Radiation doses to 28 organs were determined for 824 COPD patients undergoing routine chest examinations at three different CT systems–a conventional multi-slice CT (MSCT), a 2nd generation (2nd-DSCT), and 3rd generation dual-source CT (3rd-DSCT). Patients examined at the 3rd-DSCT received a paired inspiratory-expiratory scan. Organ doses, effective doses, and lifetime attributable cancer risks (LAR) were calculated. All organ and effective doses were significantly lower for the paired inspiratory-expiratory protocol (effective doses: 4.3 ± 1.5 mSv (MSCT), 3.0 ± 1.2 mSv (2nd-DSCT), and 2.0 ± 0.8 mSv (3rd-DSCT)). Accordingly, LAR was lowest for the paired protocol with an estimate of 0.025 % and 0.013% for female and male patients (50 years) respectively. Image quality was not compromised. Paired inspiratory-expiratory scans can be acquired on 3rd-DSCT systems at substantially lower dose and risk levels when compared to inspiration-only scans at conventional CT systems, offering promising prospects for improved COPD diagnosis.

Hepatic Blood Volume Imaging with the Use of Flat-Detector CT Perfusion in the Angiography Suite: Comparison with Results of Conventional Multislice CT Perfusion

PurposeTo prospectively determine the feasibility of flat-detector (FD) computed tomography (CT) perfusion to measure hepatic blood volume (BV) in the angiography suite in patients with hepatocellular carcinoma (HCC). Materials and MethodsTwenty patients with HCC were investigated with conventional multislice and FD CT perfusion. CT perfusion was carried out on a multislice CT scanner, and FD CT perfusion was performed on a C-arm angiographic system, before transarterial chemoembolization procedures. BV values of conventional and FD CT perfusion were measured within tumors and liver parenchyma. The arterial perfusion portion of CT perfusion BV was extracted from CT perfusion BV by multiplying it by a hepatic perfusion index. Relative values (RVs) for CT perfusion arterial BV and FD CT perfusion BV (FD BV) were defined by dividing BV of tumor by BV of parenchyma. Relationships between BV and RV values of these two techniques were analyzed. ResultsIn all patients, both perfusion procedures were technically successful, and all 33 HCCs larger than 10 mm were identified with both imaging methods. There were strong correlations between the absolute values of FD BV and CT perfusion arterial BV (tumor, r = 0.903; parenchyma, r = 0.920; both P < .001). Bland–Altman analysis showed a mean difference of −0.15 ± 0.24 between RVs for CT perfusion arterial BV and FD BV. ConclusionsThe feasibility of FD CT perfusion to assess BV values of liver tumor and surrounding parenchyma in the angiographic suite was demonstrated.

Intra-operative assessment of femoral antetorsion using ISO-C 3D: A cadaver study

AimThe aim of this study was to check the feasibility and accuracy of measuring antetorsion during surgery using a mobile image intensifier (IF) with computed tomography (CT) function (ISO-C 3D; Siemens, Erlangen, Germany) in comparison to a conventional multi-slice CT scanner (LightSpeed QX/I CT; GE Healthcare, VA, USA). Materials and methodsA total of 10 intact femora with intact soft tissue of five fresh frozen cadavers were used. After fixation on a surgical table, IF CT scans of the hip and knee were performed at both 190° and 120° of scanning rotation. Afterwards, a conventional CT scan was performed. Antetorsion was calculated according to the method of Jend et al. Analysis of variance (ANOVA) and Lin's concordance correlation coefficient (LCC) were used to test the agreement between the three measurement techniques. ResultsThere was no significant difference in femoral antetorsion angle measurements between the different techniques (P>0.05). The mean time required to perform a scan using the ISO-C 3D was 9±3min. The mean time required to measure antetorsion was 8±2min. We found a high positive correlation between CT-based measurements and measurements performed using both the ISO-C 3D at 190° (LCC=0.99; mean difference=0.02°±1.8°) and the ISO-C 3D at 120° (LCC=0.99; mean difference=0.6°±1.5°), and a high positive correlation was also seen between both ISO-C 3D methods (LCC=0.99; mean difference=0.6°±1.7°). ConclusionsMeasuring femoral antetorsion using an intra-operative IF with CT function is a feasible and accurate method. This technique could be used when there is doubt about the antetorsion angle in the operated femur and it could help decrease the need for a separate revision surgery.

Otosclerosis

To assess the use of cone beam computed tomography (CBCT) compared with multi-slice computed tomography (MSCT) in otosclerosis, with special emphasis on middle- and inner-ear anatomy. Prospective study. Twenty patients who underwent a stapedectomy 30 years ago were selected on the basis of bone conduction threshold values. Their mean age was 65 years (range, 48-76 yr). All patients underwent CBCT and MSCT with a slice thickness of 0.5 to 0.6 mm. Sixteen middle- and inner-ear anatomic structures and stapedial prostheses were analyzed by visual grading analysis. To assess critical reproduction and thereby the clinical applicability of CBCT, a dichotomization was made. Assessment of otosclerotic foci was performed using a grading system dividing the lesions in; (1) sole fenestral lesions, (2) retrofenestral lesions with or without fenestral lesions and (3) severe retrofenestral lesions. The 16 anatomic structures were clearly reproduced by both imaging techniques. However, there was an interobserver variation in judging the superiority of 1 method in favor of the other. Otosclerotic lesions were diagnosed in 80/95% using MSCT and 50/85% using CBCT (evaluators 1 and 2, respectively). Retrofenestral lesions were diagnosed in 5 of 10 of ears with severe-to-profound hearing loss, whereas no retrofenestral lesions were diagnosed in the 10 ears with mild-to-moderate hearing loss. The stapedial prostheses were adequately or very well reproduced by both methods. CBCT is a new imaging technique with a considerably lower radiation dose than conventional MSCT. Our study indicates that CBCT is suitable and, in many ways, equivalent to MSCT, for temporal bone imaging in otosclerosis.

Real three-dimensional assessment of left atrial and left atrial appendage volumes by 64-slice spiral computed tomography in individuals with or without cardiovascular disease

Context Left atrial (LA) volume is a prognosis factor of cardiovascular morbidity in patients with cardiovascular disease (CD). Recent developments of multislice computed tomography (MSCT) have made non invasive coronary angiography reliable for selected patients and new software facilitates truly volume measurements without geometrical assumptions. Objective To define, by using MSCT, LA and left atrial appendage (LAA) volumes in patients with or without CD. Methods and results In the population of patients referred to our laboratory for a conventional MSCT coronary angiography, 40 individuals without CD (Normal group) and 80 patients with CD (CD group) were prospectively selected. The CD group was constituted from 4 subgroups of patients with either coronary artery disease ( n = 20), idiopathic dilated cardiomyopathy ( n = 20), left ventricular hypertrophy ( n = 20) or severe mitral regurgitation (MR group, n = 20). LAA and LA volumes were measured on a commercially available workstation. LA maximal and minimal volumes were lower in Normal group than in CD group, as LA ejection fraction (54 ± 10 versus 67 ± 20 ml/m 2, p < 0.0001; 31 ± 8 versus 46 ± 20 ml/m 2, p < 0.0001; 43 ± 8% versus 33 ± 14%, p < 0.001). LAA volume was larger in MR group than in Normal group (15 ± 7 ml versus 9 ± 3 ml, p < 0.0001). Conclusion This MSCT study provides normal values of LA and LAA volumes for patients who underwent MSCT coronary angiography and suggests that MSCT is helpful to assess the changes of LA volumes related to various CD.

Superiority of synchrony of 256-slice cone beam computed tomography for acquiring pulsating objects. Comparison with conventional multislice computed tomography

Purpose A prototype 256-slice cone beam computed tomography (CT) provides complete volumetric data within a single gantry rotation (1 s/rotation) with 0.5 mm slice-thickness. Materials and Methods Calcified phantoms (200–400 HU) were attached to the balloon of a pulsating phantom and moved at a rate of 5–90/min. Acquisition was performed during one to-and-fro motion at each pulsation rate without electrocardiogram (ECG)-gating. Each period was divided into 10 phases, and compared to conventional multislice CT scanning without ECG-gating. Results At 5–20/min, the configuration of calcified phantoms continued to the through-plane without gaps. At 60/min, duplicated calcified phantoms at end-systole and end-diastole were observed without motion. At 90/min, motion could be observed without gaps but was more blurred, and total calcified volume, Agatston scores, mean and max CT values of three phantoms were almost equal compared with those at static state. However, at 60/min, total calcified volume, scores, mean and max CT values of three phantoms were decreased to 64%, 37%, 80% and 56%, respectively, compared with those at static state. In multislice CT, even at lower rates, there were gaps in the through-plane. At 60/min, total calcified volume, scores, mean and max CT values of three phantoms were decreased to only 8%, 3%, 79% and 53%, respectively, compared with static state. Conclusion This new prototype's unique character (synchrony) enables the acquisition of pulsating objects. These can be acquired without gaps in the through-plane even in the absence of ECG-gating. However, its present temporal resolution only permits accurate quantitative evaluation of calcium up to 20/min.