Assessment of Hemodynamic Compromise Using Computed Tomography Perfusion in Combination with 123I-IMP Single-Photon Emission Computed Tomography without Acetazolamide Challenge Test.

OBJECTIVES: The acetazolamide challenge test in conjunction with 123I-IMP single-photon emission computed tomography (SPECT) is a known method of assessing cerebrovascular reserve capacity. In this study, we investigated whether CT perfusion in combination with resting state 123I-IMP SPECT could be used instead of the acetazolamide challenge test to evaluate hemodynamic compromise in patients with atherosclerotic occlusive disease. METHODS: Twenty consecutive patients with unilateral internal carotid artery or middle cerebral artery steno-occlusive disease were enrolled. 123I-IMP SPECT was performed with and without the acetazolamide challenge test, and with CT perfusion. Cerebral blood flow (CBF), cerebral blood volume, and mean transit time (MTT) obtained by CT perfusion were compared with CBF and cerebrovascular reactivity (CVR) obtained by 123I-IMP SPECT. RESULTS: The asymmetry ratio of MTT as measured by CT perfusion showed a strong correlation with the CVR to acetazolamide as measured by 123I-IMP SPECT (ρ = -.780, P <.001). Based on the CBF obtained through 123I-IMP SPECT and the MTT obtained through CT perfusion, hemodynamic compromise was detected with high sensitivity (1.000) and specificity (.929), and a cutoff value of 30% was found to be suitable for the asymmetry ratio of MTT. MTT prolongation was significantly improved after revascularization surgery in hemodynamic compromise (P = .028). CONCLUSION: MTT as measured by CT perfusion in combination with CBF as measured by resting state 123I-IMP SPECT may be useful for evaluating hemodynamic compromise as an alternative to the acetazolamide challenge test.

Assessment of moyamoya disease using multidetector row computed tomography.

The recent introduction of multidetector row computed tomography (MDCT) scanners has enabled high-resolution 3-dimensional reconstruction. The purpose of this study was to establish a method to evaluate moyamoya disease using computed tomography angiography (CTA), specifically MDCT. Twenty-four patients (48 sides total) with moyamoya disease diagnosed by magnetic resonance angiography (MRA) were evaluated by means of CTA using MDCT by 3 independent observers, and the resulting 144 sides were analyzed. CTA and MRA were compared in terms of the steno-occlusive changes exhibited in each vessel. CTA and MRA scores were assigned on the basis of the severity of occlusive changes in the internal carotid artery, middle cerebral artery, anterior cerebral artery, and posterior cerebral artery. CTA scores were significantly correlated with MRA scores (P < .0001), and the 2 scores were in complete agreement in 57 sides (39.6%). The mean CTA score was significantly lower than the mean MRA score (P < .0001). Compared with CTA, MRA overestimated occlusion in 115 of the 576 vessels assessed. The mean MRA score was significantly higher in the overestimation group than in the good correlation group (P < .0001). CTA had a significantly higher rate of detection of moyamoya-affected vessels (P = .0001). Our data indicate that CTA using MDCT is a more reliable technique than MRA for diagnosing moyamoya disease. The ability to perform CTA quickly is a significant benefit for patients with moyamoya disease, particularly in pediatric and emergency cases.

Presurgical planning for arteriovenous malformations using multidetector row CT.

Microsurgical resection remains an important treatment for cerebral arteriovenous malformations (AVMs). We developed an accurate method for planning AVM resections using multidetector row CT (MDCT). Between January 2007 and January 2011, 21 consecutive patients with AVMs were enrolled in this study. Sixteen patients were symptomatic, and of these, 15 had a hemorrhagic onset. Preoperative CT angiography (CTA) was performed using an MDCT scanner (GE Lightspeed VCT; GE Healthcare, Milwaukee, WI, USA). In total, 1 to 1.2 mL/kg of iopamidol, a low-osmolar iodinated contrast material, was administered intravenously with the bolus tracking method. In all cases, three-dimensional CTA imaging demonstrated critical arterial feeders and their specific geometric associations with the nidus. Accurate visualization of the architecture of AVMs and surgical trajectory was possible with the volume rendering method, especially when using transparency imaging. Additionally, employing feeder extraction imaging with segmentation post-processing, clear preoperative identification of the feeding arteries around the surrounding structures allowed for not only intraoperative orientation but also planning for presurgical embolization. Moreover, the precise anatomical structures of the brain surface were obtained using fusion imaging with MRI. While it is difficult to scientifically assign a value to a technology, we sought to objectively assess the utility of the currently available CTA. The significant benefits of this modality for presurgical planning include enhanced surgeon confidence and optimization of the sequence of surgical procedures.

Visceral obesity in Japanese patients with metabolic syndrome: reappraisal of diagnostic criteria by CT scan.

To reappraise the cutoff level of abdominal circumference (AC) for diagnosis of visceral obesity in Japanese, we examined the association of visceral fat deposition with other constituents of metabolic syndrome and atherosclerotic cardiovascular disease (ASCD). CT was used for determination of visceral-fat area (VFA), subcutaneous-fat area (SFA) and AC on CT (AC(CT)) in 420 Japanese patients with (n=180) or without ASCD (n=240). VFA cutoff levels were calculated by receiver operating characteristic (ROC) analysis. AC(CT) correlated with VFA (r=0.828), SFA (r=0.795), and AC measured with an anthropometric tape (AC(M), r=0.96). The VFA cutoff levels yielding the maximum sensitivity and specificity to predict two or more components of metabolic syndrome were 92 cm(2) in males and 63 cm(2) in females, which correspond to AC(M) values of 83 cm and 78 cm, respectively. The male AC(M) cutoff level was similar to the AC in current Japanese criteria (85 cm), but the female AC(M) cutoff level was considerably smaller than the criteria, and this change in cutoff level increased the prevalence of metabolic syndrome in females three-fold. The cutoff levels of VFA for predicting presence of ASCD were 98 cm(2) in males and 75 cm(2) in females, corresponding to AC(M) values of 84 cm and 80 cm, respectively. The present results obtained by CT support the validity of the current Japanese criteria for visceral obesity in males but not in females. AC(M) of 78 cm appears to be a cutoff level suitable for diagnosing visceral obesity in Japanese females, though further confirmation is needed.

[Evaluation of three-dimensional enhanced brain surface imaging using CT (3D surface CT angiography) and magnetic resonance imaging (3D surface MR angiography)].

The optimal imaging conditions for 3D brain surface imaging by magnetic resonance imaging (MRI) and multi-slice CT were investigated. Visualization of the sulci, gyri, and veins on the brain's surface was also compared between 3D surface images acquired using multi-slice CT and conventional single-slice CT and MRI. Various imaging parameters, including slice thickness, dose, and matrix size, were evaluated using our original brain surface phantom and longitudinal direction evaluation phantom as well as images obtained from healthy volunteers. Subjects of the clinical study were patients with arteriovenous malformations and brain tumors who underwent CT-angiography at the same time as MR-angiography. The quality of 3D images of the brain surface is most strongly influenced by partial volume effects related to slice thickness. In multi-slice CT, a slice thickness of 0.5 mm can be employed to minimize the partial volume effect, providing results that are far superior to those that can be achieved by conventional single-slice 3D-CT. In addition, the excellent S/N of multi-slice CT permits the veins on the brain's surface to be clearly visualized without the use of contrast medium. With regard to visualization of the sulci and gyri, although some problems remain to be overcome, multi-slice CT was found to be equivalent to 3D surface imaging using MRI.

[Image quality assessment of Step&Shoot overlap reconstruction (SSOR) for cardiac computed tomography (CT)].

BACKGROUND: Step&Shoot cardiac computed tomography (CT) provides the benefit of significant reduction in radiation dose compared to helical cardiac CT acquisitions. We think that a difference occurs in image quality by presence of overlap reconstruction (fractionated sentence, attempted to clarify). PURPOSE: We studied the utility of Step&Shoot overlap reconstruction (SSOR). METHODS: We evaluated image quality of SSOR by comparing z-axis spatial resolution on various s in scanners that SSOR is possible and for those that are impossible. RESULTS: SSOR indicated better z-axis spatial resolution and less variation over the field of view (FOV) (in z & x-y directions) as compared with Step&Shoot without overlap reconstruction (SS). In addition, SS showed inadequate image reproducibility due to aliasing error in z-direction (lack of sampling interval). CONCLUSIONS: SSOR would contribute to improvement of the image quality of Step&Shoot cardiac CT.