Bayesian estimation with advanced noise reduction (BEANR) in CT perfusion (CTP) could deliver more reliable cerebral blood flow (CBF) measurements than the commonly used reformulated singular value decomposition (rSVD). We compared the efficacy of CBF measurement by CTP using BEANR and rSVD, evaluating both relative to N-isopropyl-p-[(123) I]- iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT) as a reference standard, in patients with cerebrovascular disease. Thirty-one patients with suspected cerebrovascular disease underwent both CTP on a 320 detector-row CT system and SPECT. We applied rSVD and BEANR in the ischemic and contralateral regions to create CBF maps and calculate CBF ratios from the ischemic side to the healthy contralateral side (CBF index). The analysis involved comparing the CBF index between CTP methods and SPECT using Pearson’s correlation and limits of agreement determined with Bland–Altman analyses, before comparing the mean difference in the CBF index between each CTP method and SPECT using the Wilcoxon matched pairs signed-rank test. The CBF indices of BEANR and 123I-IMP SPECT were significantly and positively correlated (r = 0.55, p < 0.0001), but there was no significant correlation between the rSVD method and SPECT (r = 0.15, p > 0.05). BEANR produced smaller limits of agreement for CBF than rSVD. The mean difference in the CBF index between BEANR and SPECT differed significantly from that between rSVD and SPECT (p < 0.001). BEANR has a better potential utility for CBF measurement in CTP than rSVD compared to SPECT in patients with cerebrovascular disease.

PURPOSE:Diagnostic and neurosurgical procedures require the precise localization of small intracranial arteries, but this may be difficult using conventional computed tomography angiography (CTA). This study was conducted to evaluate the quality of CTA images acquired using a prototype ultra-high-resolution computed tomography (U-HRCT) system compared with those acquired using a conventional computed tomography (C-CT) system. MATERIALS AND METHODS:From July through September 2015, 10 adult patients (6 women and 4 men) previously scanned by C-CT were examined using U-HRCT to locate and assess cerebral aneurysms. The bilateral ophthalmic artery (Opth A), anterior choroidal artery (Acho A), and thalamoperforating arteries (TPAs) were visually evaluated in randomly presented CTA images. Images were graded on a 5-point scale, and differences in scores between U-HRCT and C-CT were evaluated by the Wilcoxon signed-rank test. A p value < 0.05 was considered statistically significant. RESULTS:Visual evaluation scores for images of the Opth A, Acho A, and TPAs were significantly higher for U-HRCT than for C-CT. U-HRCT images achieved good visualization (score > 3) for C-CT images with poor visualization (score < 3) in 66.7-100% of all the small arteries. CONCLUSION:U-HRCT is superior to C-CT for detecting and evaluating clinically significant small intracranial arteries.

BACKGROUND:Limitations of coronary computed tomography (CTA) include false-positive stenosis at calcified lesions and assessment of in-stent patency. A prototype of ultra-high resolution computed tomography (U-HRCT: 1,792 channels and 0.25-mm slice thickness×128 rows) with improved spatial resolution was developed. We assessed the diagnostic accuracy of coronary artery stenosis using U-HRCT. METHODS AND RESULTS:Seventy-nine consecutive patients who underwent CTA using U-HRCT were prospectively included. Coronary artery stenosis was graded from 0 (no plaque) to 5 (occlusion). Stenosis grading at 102 calcified lesions was compared between U-HRCT and conventional-resolution CT (CRCT: 896 channels and 0.5-mm slice thickness×320 rows). Median stenosis grading at calcified plaque was significantly improved on U-HRCT compared with CRCT (1; IQR, 1-2 vs. 2; IQR, 1-3, P<0.0001). Assessability of in-stent lumen was evaluated on U-HRCT in 79 stents. Stent strut thickness and luminal diameter were quantitatively compared between U-HRCT and CRCT. Of 79 stents, 83.5% were assessable on U-HRCT; 80% of stents with diameter 2.5 mm were regarded as assessable. On U-HRCT, stent struts were significantly thinner (median, 0.78 mm; IQR, 0.7-0.83 mm vs. 0.83 mm; IQR, 0.75-0.92 mm, P=0.0036), and in-stent lumens were significantly larger (median, 2.08 mm; IQR, 1.55-2.51 mm vs. 1.74 mm; IQR, 1.31-2.06 mm, P<0.0001) than on CRCT. CONCLUSIONS:U-HRCT with improved spatial resolution visualized calcified lesions with fewer artifacts. The in-stent lumen of stents with diameter ≥2.5 mm was assessable on U-HRCT.

Purpose: We evaluated the diagnostic performance of histogram analysis of data from a combination of dynamic susceptibility contrast (DSC)-MRI and dynamic contrast-enhanced (DCE)-MRI for quantitative differentiation between central nervous system lymphoma (CNSL) and high-grade glioma (HGG), with the aim of identifying useful perfusion parameters as objective radiological markers for differentiating between them. Methods: Eight lesions with CNSLs and 15 with HGGs who underwent MRI examination, including DCE and DSC-MRI, were enrolled in our retrospective study. DSC-MRI provides a corrected cerebral blood volume (cCBV), and DCE-MRI provides a volume transfer coefficient (K-trans) for transfer from plasma to the extravascular extracellular space. K-trans and cCBV were measured from a round region-of-interest in the slice of maximum size on the contrast-enhanced lesion. The differences in t values between CNSL and HGG for determining the most appropriate percentile of K-trans and cCBV were investigated. The differences in K-trans, cCBV, and K-trans/cCBV between CNSL and HGG were investigated using histogram analysis. Receiver operating characteristic (ROC) analysis of K-trans, cCBV, and Ktrans/cCBV ratio was performed. Results: The 30th percentile (C30) in K-trans and 80th percentile (C80) in cCBV were the most appropriate percentiles for distinguishing between CNSL and HGG from the differences in t values. CNSL showed significantly lower C80 cCBV, significantly higher C30 K-trans, and significantly higher C30 K-trans/C80 cCBV than those of HGG. In ROC analysis, C30 K-trans/C80 cCBV had the best discriminative value for differentiating between CNSL and HGG as compared to C30 K-trans or C80 cCBV. Conclusion: The combination of K-trans by DCE-MRI and cCBV by DSC-MRI was found to reveal the characteristics of vascularity and permeability of a lesion more precisely than either K-trans or cCBV alone. Histogram analysis of these vascular microenvironments enabled quantitative differentiation between CNSL and HGG.

Noncontrast computed tomography (NCCT) has been used for the detection of early ischemic change (EIC); however, correct interpretation of NCCT findings requires much clinical experience. This study aimed to assess the accuracy of time maximum intensity projection computed tomography technique (tMIP), which reflects the maximum value for the time phase direction from the dynamic volume data for each projected plane, for detection of EIC, against that of NCCT.Retrospective review of NCCT, cerebral blood volume in CT perfusion (CTP-CBV), and tMIP of 186 lesions from 280 regions evaluated by Alberta Stroke Program Early CT Score (ASPECTS) in 14 patients with acute middle cerebral artery stroke who had undergone whole-brain CTP using 320-row area detector CT was performed. Four radiologists reviewed EIC on NCCT, CTP-CBV, and tMIP in each ASPECTS region at onset using the continuous certainty factor method. Receiver operating characteristic analysis was performed to compare the relative performance for detection of EIC. The correlations were evaluated.tMIP-color showed the best discriminative value for detection of EIC. There were significant differences in the area under the curve for NCCT and tMIP-color, CTP-CBV (P<.05). Scatter plots of ASPECTS showed a positive significant correlation between NCCT, tMIP-gray, tMIP-color, and the follow-up study (NCCT, r=0.32, P=.0166; tMIP-gray, r=0.44, P=.0007; tMIP-color, r=0.34, P=.0104).Because tMIP provides a high contrast parenchymal image with anatomical and vascular information in 1 sequential scan, it showed greater accuracy for detection of EIC and predicted the final infarct extent more accurately than NCCT based on ASPECTS.

This study aimed to (1) evaluate changes in bolus and air volumes in the pharyngo-laryngeal cavity during swallowing and (2) determine how differences in these volumes during swallowing are influenced by bolus amount using 320-row area detector computed tomography (320-ADCT). Three-, 10-, and 20-ml honey-thick liquids (5% w/v) were presented to ten healthy subjects placed in a 45° reclining position. 3D images were created in 29 phases at an interval of 0.1 s for 3.15 s. Changes in bolus and air volumes in the pharyngo-laryngeal cavity were calculated. The two one-sided tests were used to determine equivalency of the pharyngo-laryngeal volume of each event (i.e., onset of hyoid elevation, soft palate closure, true vocal cord closure, closure of laryngeal vestibule, epiglottis inversion, pharyngo-esophageal sphincter opening) for each bolus volume. The pharyngo-laryngeal volume during swallowing was about 20 ml before swallowing. The volume temporarily increased with tongue loading, but decreased to about 0 ml with pharyngeal contraction. Subsequently, the volume returned to the original volume after airway opening. Most of the air was released from the pharyngo-laryngeal space before the bolus flowed into the esophagus during swallowing. As the bolus volume to be swallowed increased, the maximal pharyngo-laryngeal volume increased, but changes in air volume remained constant. 320-ADCT allowed for analysis of dynamic volume changes in the pharyngo-laryngeal cavity, which will increase our knowledge of kinematic and volumetric mechanisms during swallowing.

Introduction: One of the limitations of coronary CT angiography (CTA) is the difficulty to evaluate the luminal stenosis at calcified plaques. Novel CT scanner with higher spatial resolution was de...

OBJECTIVE:We aimed to clarify the cause of shortened mean transit time (MTT) in acute ischemic cerebrovascular disease and examined its relationship with reperfusion.METHODS:Twenty-three patients with acute ischemic cerebrovascular disease underwent whole-brain computed tomography perfusion (CTP). The maximum MTT (MTTmax), minimum MTT (MTTmin), ratio of maximum and minimum MTT (MTTmin/max), and minimum cerebral blood volume (CBV) (CBVmin) were measured by automatic region of interest analysis. Diffusion weighted image was performed to calculate infarction volume. We compared these CTP parameters between reperfusion and nonreperfusion groups and calculated correlation coefficients between the infarction core volume and CTP parameters.RESULTS:Significant differences were observed between reperfusion and nonreperfusion groups (MTTmin/max: P = 0.014; CBVmin ratio: P = 0.038). Regression analysis of CTP and high-intensity volume on diffusion weighted image showed negative correlation (CBVmin ratio: r = -0.41; MTTmin/max: r = -0.30; MTTmin ratio: r = -0.27).CONCLUSIONS:A region of shortened MTT indicated obstructed blood flow, which was attributed to the singular value decomposition method error.

The American College of Radiology opened the computed tomography (CT) dose index registry (DIR) for general participation by all facilities in 2011. For each CT examination, data on volume CT dose index (CTDIvol), dose-length product (DLP), and, for body examinations, size-specific dose estimate (SSDE) were collected. However, effective dose is not estimated in DIR. The primary objective of this study was to estimate k-factor profile in detail at various scan positions with modified the ImPACT CT patient dosimetry. A tool that easily estimates the k-factor of suitable scan areas is essential for practical dose estimation in the DIR. We evaluated k-factor (effective dose/ DLP) profiles between a medical international radiation dose-five (MIRD-5) phantom positions using aImPACT software. As a result of this study, practicality of the k-factor profile method in clinical use was clarified. We speculate that a flexible k-factor improves the appropriateness of the E in hospital settings.

The relationship between heart rate (HR) and computed tomography dose index (CTDI) was evaluated using an electrocardiogram (ECG) gate scan for scan applications such as prospective triggering, Ca scoring, target computed tomography angiography (CTA), prospective CTA and retrospective gating, continuous CTA/CFA (cardiac functional analysis) and CTA/CFA modulation. Even in the case of a volume scan, doses for the multiple scan average dose were similar to those for CTDI. Moreover, it was found that the ECG gate scan yields significantly different doses. When selecting the optimum scan, the doses were dependent on many factors such as HR, scan rotation time, active time, prespecified cardiac phase and modulation rate. Therefore, it is necessary to take these results into consideration when selecting the scanning parameters.

Objective: We compared cerebral blood flow (CBF) measured using computed tomographic (CT) perfusion (CTP) and N-isopropyl-p-[(123) I]-iodoamphetamine cerebral perfusion single-photon emission computed tomography (SPECT).Methods: We used a 320-row area detector CT and N-isopropyl-p-[(123) I]-iodoamphetamine cerebral perfusion SPECT under similar conditions in patients with chronic cerebrovascular disease. Images were automatically aligned 3-dimensionally for voxel-by-voxel comparisons.Results: Linear positive correlations were observed between CTP-CBF including high-blood-flow areas and SPECT-CBF over the whole brain (r = 0.001-0.6, P < 0.01), superior cerebral level (r = 0.45-0.93, P < 0.01), basal ganglia level (r = 0.44-0.77, P < 0.01), and skull base (r = 0.02-0.66, P < 0.01). Correlations between CTP-CBF excluding high-blood-flow areas were significantly higher (P < 0.0001).Conclusions: Computed tomographic perfusion overestimated CBF compared with SPECT and showed poor correlation at the skull base. Computed tomographic perfusion CTP excluding high-blood-flow areas improved the correlation over the whole brain in patients with chronic cerebrovascular disease.

Personal dose equivalent, H p (10) and H p (0.07) doses were measured using an ionization chamber and personal electric dosimeters to estimate the exposure dose for medical staff members and carers as received from 89 Sr therapy patients.The H p (10) for medical workers was measured using personal dosimeters and was found to be <1 μSv during the measurement period.H p (0.07) for medical workers did not exceed 5 μSv per case during routine work, although the dose on the patient's skin surface was about 20 times that on the medical staff.To investigate the contribution of electrons to the measured dose, the dose on the patient's skin surface as obtained from uniformly distributed 89 Sr in a similar MIRD phantom was calculated using EGS5 code.The peak energy of the incident photons was approximately 0.6 MeV.The estimated H p (10) and H p (0.07) doses for the medical staff were 0.43 and 91 μSv/h, respectively.The contribution of electrons to the calculated H p (0.07) was approximately 200 times that of photons.Thus, the high H p (0.07) for medical staff is attributed to the strong contribution of electrons. Keywords: 89 Sr for bone

We modified the Imaging Performance Assessment of CT scanners (ImPACT) to evaluate the organ doses and the effective dose based on the International Commission on Radiological Protection (ICRP) Publication 110 reference male/female phantom with the Aquilion ONE ViSION Edition scanner. To select the new CT scanner, the measurement results of the CTDI100, c and CTDI100, p for the 160 (head) and the 320 (body) mm polymethylmethacrylate phantoms, respectively, were entered on the Excel worksheet. To compute the organ doses and effective dose of the ICRP reference male/female phantom, the conversion factors obtained by comparison between the organ doses of different types of phantom were applied. The organ doses and the effective dose were almost identical for the ICRP reference male/female and modified ImPACT. The results of this study showed that, with the dose assessment of the ImPACT, the difference in sex influences only testes and ovaries. Because the MIRD-5 phantom represents a partially hermaphrodite adult, the phantom has the dimensions of the male reference man including testes, ovaries, and uterus but no female breasts, whereas the ICRP male/female phantom includes whole-body male and female anatomies based on high-resolution anatomical datasets. The conversion factors can be used to estimate the doses of a male and a female accurately, and efficient dose assessment can be performed with the modified ImPACT.

In patients with unilateral pharyngeal paresis and dysphagia, the head is rotated to the paretic side to prevent food flow to the rotated side during swallowing. Only a few studies to date have reported on pyriform sinus morphology upon head rotation. The purpose of this study was to measure the volume, depth, and cross-sectional area of the pyriform sinus during head rotation using 320-row area detector computed tomography. We imaged the neck during head rotation at 0° and at 30°, 45°, and 60° to the left or right in nine healthy young adults and determined the volume, depth, and cross-sectional area of the pyriform sinus in each position. On the rotated side, volume and cross-sectional area were significantly decreased at 60°. In contrast, volume, cross-sectional area, and depth were all significantly increased on the opposite side at 60°. These results suggest that head rotation at 60° significantly increases the volume, cross-sectional area, and depth of the opposite side, and significantly decreases the volume and depth of the rotated side of the pyriform sinus.

We report here a case of rupture of a substitute urinary bladder due to a relapse of bladder cancer detected incidentally on a bone scan. The radionuclides used in bone scans accumulate in the bone and are excreted in the urine. Incidental detection of rupture of a substitute urinary bladder may lead to appropriate intermediate neobladder repair.

OBJECTIVE:The Eustachian tube is difficult to evaluate because it is located deep in the head. However, the introduction of 320-row area detector CT has made it possible to evaluate this region. In the present study, movement of the Eustachian tube during sniffing was visualized using area detector CT in patients with patulous Eustachian tube.METHODS:Four patients with patulous Eustachian tube were examined using an area detector CT scanner (Aquilion ONE, Toshiba). This scanner supports 320-row scanning of 0.5-mm slices at up to 0.275 s/rot., eliminating temporal mismatch between various parts of the acquired images and permitting 4-dimensional CT (4DCT) images to be obtained by continuous scanning. The scan conditions were 120 kV, 120 to 150 mA, 0.5 mm × 280 to 320 slices, and 0.35 seconds per rotation × 9 rotations. The patient was seated on a reclining chair tilted to 45 degrees and was instructed to sniff during continuous scanning. Images of the Eustachian tube were generated at 0.1-second intervals.CONCLUSION:At the start of sniffing, the cartilaginous portion of the Eustachian tube closed from the isthmus toward the pharynx. The starting point differed from patient to patient. In patients with patulous Eustachian tube, sniffing (an unconscious habit that helps to relieve ear discomfort) is an important factor in the development of middle ear diseases. We have successfully depicted this event for the first time, demonstrating various patterns of Eustachian tube closure during sniffing in patients with patulous Eustachian tube. This method may be useful for evaluating Eustachian tube dysfunction.

BACKGROUND:Radiation pneumonitis (RP) and organizing pneumonia (OP) are the two main types of lung damage that can occur after lung irradiation. The goal of this study was to evaluate the relationship between RP and OP after irradiation for breast cancer.METHODS:Four hundred and twenty-eight patients who underwent radiotherapy for breast cancer were identified. The whole breast was irradiated with two tangential photon beams. Chest computed tomography (CT) scan were performed when patients showed any symptoms that were suspicious for pneumonitis.RESULTS:Five patients (1.2%) were diagnosed with OP. All five patients showed ground glass opacities and consolidation of the border of the lesion of RP in the radiation fields. Infiltration of OP spread from the site of RP to the hilum of the ipsilateral lung. Between RP and OP, a free region space (FRS) could be detected.CONCLUSIONS:OP is closely related to RP. All OP lesions developed near the site of RP.