High-angular resolution diffusion imaging generation using 3d u-net.

PURPOSE: To investigate the effects on tractography of artificial intelligence-based prediction of motion-probing gradients (MPGs) in diffusion-weighted imaging (DWI). METHODS: The 251 participants in this study were patients with brain tumors or epileptic seizures who underwent MRI to depict tractography. DWI was performed with 64 MPG directions and b = 0 s/mm2 images. The dataset was divided into a training set of 191 (mean age 45.7 [± 19.1] years), a validation set of 30 (mean age 41.6 [± 19.1] years), and a test set of 30 (mean age 49.6 [± 18.3] years) patients. Supervised training of a convolutional neural network was performed using b = 0 images and the first 32 axes of MPG images as the input data and the second 32 axes as the reference data. The trained model was applied to the test data, and tractography was performed using (a) input data only; (b) input plus prediction data; and (c) b = 0 images and the 64 MPG data (as a reference). RESULTS: In Q-ball imaging tractography, the average dice similarity coefficient (DSC) of the input plus prediction data was 0.715 (± 0.064), which was significantly higher than that of the input data alone (0.697 [± 0.070]) (p < 0.05). In generalized q-sampling imaging tractography, the average DSC of the input plus prediction data was 0.769 (± 0.091), which was also significantly higher than that of the input data alone (0.738 [± 0.118]) (p < 0.01). CONCLUSION: Diffusion tractography is improved by adding predicted MPG images generated by an artificial intelligence model.

[Assessment Tool of Image Quality for Medical Liquid-crystal Displays Using Commercially Available Digital Cameras].

We developed a simplified tool for measuring image quality of medical liquid-crystal displays (LCDs) using a commercially available color digital camera. This tool implemented as a plug-in software for ImageJ (open-source image processing program) was designed to compute modulation transfer functions (MTFs) and Wiener spectra (WS) of monochrome and color LCDs from LCD photographed images captured by a camera. The intensities of the red (R), green (G), and blue (B) signals of the unprocessed image data depend on the spectral sensitivity of the image sensor used in the camera. In order to evaluate image quality based on LCD luminance, the plug-in software calibrates the RGB signals from the camera using measured luminance of the LCD and converts them into grayscale signals that correspond to the luminance of the LCD. The MTFs and WS are determined based on the line response from a one-pixel line image and the one-dimensional noise profiles acquired by scanning the uniform image using numerically synthesized slit, respectively. With this plug-in software for ImageJ, we are able to readily compute MTFs and WS of both monochrome and color LCDs from unprocessed image data of cameras. Our simplified tool is helpful to evaluate and understand the physical performance of LCDs for a large number of display users in hospitals and medical centers.

[Questionnaire Survey of Radiation Protection Education in Hospitals].

PURPOSE: The present study aimed to investigate the current situation of radiation protection education for designated radiation workers in hospitals. METHODS: A web-based questionnaire survey was conducted at 1,883 hospitals nationwide with 200 or more beds. RESULTS: Responses from 186 hospitals were included in the analysis. Seven hospitals (6.7%) regulated by the Act on the Regulation of Radioisotopes and six hospitals (7.4%) regulated by only the Ordinance on Prevention of Ionizing Radiation Hazards did not implement radiation protection education. In approximately 6% of the hospitals, designated radiation workers-including physicians, nurses, and radiological technologist-did not attend the education program. The education program attendance rate of physicians was lower than that of nurses. In more than 90% of the hospitals, the frequency of the periodical education program was once every year and lecture time spanned one or less than one hour. The topics of lecture in more than 90% of the hospitals were health effects of radiation and methods of radiation protection for occupational exposure. The radiological technologist was the instructor of the education program in approximately 70% of the hospitals. CONCLUSION: The implementation of radiation protection for designated radiation workers varied from hospital to hospital, and some hospitals did not comply with laws and regulations. Effective and efficient radiation protection education models should be implemented in hospitals.

[Development of a Deep Learning Model for Judging Late Gadolinium-enhancement in Cardiac MRI].

PURPOSE: To verify the usefulness of a deep learning model for determining the presence or absence of contrast-enhanced myocardium in late gadolinium-enhancement images in cardiac MRI. METHODS: We used 174 late gadolinium-enhancement myocardial short-axis images obtained from contrast-enhanced cardiac MRI performed using a 3.0T MRI system at the University of Tokyo Hospital. Of these, 144 images were used for training, extracting a region of interest targeting the heart, scaling signal intensity, and data augmentation were performed to obtain 3312 training images. The interpretation report of two cardiology specialists of our hospital was used as the correct label. A learning model was constructed using a convolutional neural network and applied to 30 test data. In all cases, the acquired mean age was 56.4±12.1 years, and the male-to-female ratio was 1 : 0.82. RESULTS: Before and after data augmentation, sensitivity remained consistent at 93.3%, specificity improved from 0.0% to 100.0%, and accuracy improved from 46.7% to 96.7%. CONCLUSION: The prediction accuracy of the deep learning model developed in this research is high, suggesting its high usefulness.

Cortical damage following traumatic brain injury evaluated by iomazenil SPECT and in vivo microdialysis.

[(123)I] iomazenil (IMZ) single photon emission computed tomography (SPECT) has been reported to be a useful marker of neuronal integrity. We evaluated cortical damage following traumatic brain injury (TBI) with IMZ SPECT at the acute stage. After conventional therapy for a cranial trauma, an IMZ SPECT re-evaluation was performed at the chronic stage. A reduction in IMZ uptake in the location of cerebral contusions was observed during the TBI acute phase; however, images of IMZ SPECT obtained during the chronic phase showed that areas with decreased IMZ distribution were remarkably reduced compared with those obtained during the acute phase. As a result of in vivo microdialysis study, the extracellular levels of glutamate in the cortex, where decreased IMZ distribution was shown during the acute phase, were increased during the 168-h monitoring period. During the chronic phase, IMZ uptake in the region with the microdialysis probes was recovered. The results suggest that this reduction in IMZ uptake might not be a sign of irreversible tissue damage in TBI.

Correlation between Post-Acute Electroconvulsive Therapy Alpha-Band Spectrum Power Increase and Improvement of Psychiatric Symptoms.

The results of quantitative electroencephalography (qEEG) studies on electroconvulsive therapy (ECT) have been inconsistent, and indicators of the efficacy of ECT have not been clearly identified. In this study, we examined whether qEEG could be used as an indicator of the effect of ECT by measuring it during the course of treatment. We analyzed qEEG data before and after acute-phase ECT in 18 patients with schizophrenia, mood disorders, and other psychiatric disorders. We processed the qEEG data and compared the spectral power between the data acquired before and after ECT. The spectral power increased significantly after ECT in the delta, theta, and alpha bands. There was a strong significant correlation between the increase in the spectral power of the alpha band after acute ECT and improvement in the Brief Psychiatric Rating Scale score. Our results suggest that an increase in the alpha-band spectral power may be useful as an objective indicator of the treatment effect of acute ECT.

Changes in the global spine alignment in the sitting position in an automobile.

BACKGROUND CONTEXT: Studies of the changes in spine alignment in the sitting position have been limited to specific spine segments. Because there have been few studies of global spinopelvic alignment in the sitting position, it is important to assess the changes associated with this position for such settings as developing future design of seats and achieving appropriate restoration of spine alignment. PURPOSE: This study aimed to measure changes in global spine alignment when people are sitting in car seats and to analyze the characteristics of those changes. STUDY DESIGN: This was a prospective, collaborative study of the radiological evaluation of changes in global spine alignment. PATIENT SAMPLE: The study included 113 asymptomatic adult participants (56 men and 57 women) without a history of spine disease or lower limb surgery, and with no current lower back or leg pain. OUTCOME MEASURES: Radiographic findings were assessed by measurement of various angles: cervical lordosis (CL), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), C7 sagittal vertical axis (C7-SVA), T1 spinopelvic inclination (T1SPI), and T1 pelvic angle (TPA). METHODS: Radiographs were obtained in the standing and sitting positions. The objective variables analyzed statistically were spine alignments (CL, TK, TLK, LL, C7-SVA, T1SPI, TPA, SS, PT, and PI) measured in the standing position, body alignments (CL, TK, TLK, LL, C7-SVA, T1SPI, TPA, SS, and PT) measured in the sitting position, and stand-to-sit changes (∆CL, ∆TK, ∆TLK, ∆LL, ∆C7-SVA, ∆T1SPI, ∆TPA, ∆SS, and ∆PT). Explanatory variables were sex, age, body height, and body mass index. RESULTS: Changing posture from standing to sitting decreased CL by an average of 5.3°, slightly decreased TK by an average of 1.3°, increased TLK by an average of 6.8°, decreased LL by an average of 35°, decreased SS by an average of 49.2°, increased PT by an average of 49.2°, shifted C7-SVA backward by an average of 106.7 mm, decreased T1SPI by an average of 18.8°, and increased TPA by an average of 21.1°. Statistical analysis revealed that ΔLL was significantly decreased in elderly participants. After the stand-to-sit change, ΔTLK and ∆TPA were significantly increased in taller participants and ΔT1SPI was significantly decreased in taller participants. CONCLUSIONS: Among other changes, most notably LL is decreased and the pelvic tilt is increased when a person is sitting in a car seat. However, these changes in spine alignment differ with age and height. These findings may be useful for the development of future design of seats and for achieving appropriate surgical restoration of spine alignment.

Findings of hepatopulmonary syndrome on breath-hold perfusion SPECT-CT fusion images.

Pulmonary perfusion SPECT-CT fusion images were used to characterize CT manifestations of intrapulmonary arteriovenous communications (AVC) causing right-to-left shunt and hepatopulmonary syndrome (HPS). After scanning the whole body and obtaining multiple view images of the lung, deep-inspiratory breath-hold (DIBrH) SPECT was obtained in 2 patients with HPS, which was automatically and three-dimensionally co-registered with DIBrH CT. In both patients, the whole body scan depicted systemic organs and confirmed the existence of right-to-left shunt. DIBrH SPECT-CT fusion images showed that perfusion defects were predominantly located at subpleural reticulo-nodular opacities and/or dilated vessels in the lung base. Subpleural reticulo-nodular opacities and/or dilated vessels in the lung base appear to be characteristic CT manifestation of intrapulmonary AVC in HPS.

[Study of high speed rotation SPECT acquisition method with breath-hold -comparison between dual-head system and triple-head system-].

BACKGROUND: Because lung perfusion Tc-99m MAA of SPECT is generally acquired under the non-breath-hold condition, SPECT image quality is degraded for respiratory lung motion. To solve this problem, a new acquisition mode would need to be developed. We suggest that the acquisition mode is the detector rotating at high speed during the deep breath-hold condition and 20 sec. This acquisition method is known as high-speed detector rotation-multiplied projection single photon emission computed tomography (HSRMP-SPECT). Detail is reconstructed from projection data added while projection data are acquired several times under deep breath-hold sets. PURPOSE: The HSRMP-SPECT technique has been developed under the triple-head system. However, the triple-head system is a small field of view. Thus a description of the entire lung area was impossible under the deep breath-hold condition. The HSRMP-SPECT technique seems needed to make the shift to dual-head system, because the generally dual-head system has a large field of view. We were compared triple-head system with dual-head system, and researched some parameter. RESULT: With lung perfusion HSRMP-SPECT using the dual-head system, description of the entire lung area possible. The triple-head system of 5 projection data sets and dual-head system of 6 projection data sets nearly equaled the total count, and also the coefficient of variation is nearly same. Therefore, we were able to make the triple-head system to the dual-head system the shift on HSRMP-SPECT.

Relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism: assessment with breath-hold SPECT-CT pulmonary angiography fusion images.

PURPOSE: The relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism (PTE) was comprehensively assessed on deep-inspiratory breath-hold (DIBrH) perfusion SPECT-computed tomographic pulmonary angiography (CTPA) fusion images. MATERIALS AND METHODS: Subjects were 34 acute PTE patients, who had successfully performed DIBrH perfusion SPECT using a dual-headed SPECT and a respiratory tracking system. Automated DIBrH SPECT-CTPA fusion images were used to assess the relation between lung perfusion defects and intravascular clots detected by CTPA. RESULTS: DIBrH SPECT visualized 175 lobar/segmental or subsegmental defects in 34 patients, and CTPA visualized 61 intravascular clots at variable locations in 30 (88%) patients, but no clots in four (12%) patients. In 30 patients with clots, the fusion images confirmed that 69 (41%) perfusion defects (20 segmental, 45 subsegmental and 4 lobar defects) of total 166 defects were located in lung territories without clots, although the remaining 97 (58%) defects were located in lung territories with clots. Perfusion defect was absent in lung territories with clots (one lobar branch and three segmental branches) in four (12%) of these patients. In four patients without clots, nine perfusion defects including four segmental ones were present. CONCLUSION: Because of unexpected dissociation between intravascular clots and lung perfusion defects, the present fusion images will be a useful adjunct to CTPA in the diagnosis of acute PTE.

A stripe sign on 99mTc-Technegas SPECT in pulmonary emphysema.

OBJECTIVE: By focusing on a stripe sign (interposed preserved radioactivity between central defects and pleural surface of the lung), the cross-sectional ventilation difference between the central and peripheral lung in pulmonary emphysema was evaluated on Tc-Technegas SPECT, and compared with other forms of chronic obstructive pulmonary disease (COPD). METHODS: Technegas and perfusion SPECT were performed in 47 patients with relatively advanced emphysema, 15 patients with other forms of COPD without alveolar destruction and six controls. The presence or absence of a stripe sign was evaluated at upper, middle and lower lung zones on both SPECT. At stripe sign-positive lung zones on Technegas SPECT in pulmonary emphysema, the pattern of low attenuation areas (LAAs) distribution on X-ray CT was also evaluated. RESULTS: Of the total of 282 lung zones in patients with emphysema, a stripe sign was positive on Technegas SPECT at 153 (54.2%) zones in 27 (57.4%) patients, although less frequently positive on perfusion SPECT at 166 (58.8%) zones in 30 (63.8%) patients. This sign was negative on Technegas SPECT throughout the stripe sign-negative zones on perfusion SPECT. Throughout the lung zones in controls and patients with other forms of COPD, this sign was negative both on Technegas and perfusion SPECT. On X-ray CT, 124 (81%) of 153 stripe-positive lung zones on Technegas SPECT in pulmonary emphysema showed central lung-dominant LAA. CONCLUSION: In contrast to other forms of COPD, a stripe sign was frequently positive on Technegas SPECT in relatively advanced emphysema, with central-lung dominant LAA on X-ray CT. Relative preservation of peripheral lung ventilation seems to be a characteristic feature of this disease, indicating a lower susceptibility of the peripheral lung for alveolar destruction.

Assessment of anatomic relation between pulmonary perfusion and morphology in pulmonary emphysema with breath-hold SPECT-CT fusion images.

OBJECTIVE: Anatomic relation between pulmonary perfusion and morphology in pulmonary emphysema was assessed on deep-inspiratory breath-hold (DIBrH) perfusion single-photon emission computed tomography (SPECT)-CT fusion images. METHODS: Subjects were 38 patients with pulmonary emphysema and 11 non-smoker controls, who successfully underwent DIBrH and non-BrH perfusion SPECT using a dual-headed SPECT system during the period between January 2004 and June 2006. DIBrH SPECT was three-dimensionally co-registered with DIBrH CT to comprehend the relationship between lung perfusion defects and CT low attenuation areas (LAA). By comparing the appearance of lung perfusion on DIBrH with non-BrH SPECT, the correlation with the rate constant for the alveolar-capillary transfer of carbon monoxide (DLCO/VA) was compared between perfusion abnormalities on these SPECTs and LAA on CT. RESULTS: DIBrH SPECT provided fairly uniform perfusion in controls, but significantly enhanced perfusion heterogeneity when compared with non-BrH SPECT in pulmonary emphysema patients (P < 0.001). The reliable DIBrH SPECT-CT fusion images confirmed more extended perfusion defects than LAA on CT in majority (73%) of patients. Perfusion abnormalities on DIBrH SPECT were more closely correlated with DLCO/VA than LAA on CT (P < 0.05). CONCLUSIONS: DIBrH SPECT identifies affected lungs with perfusion abnormality better than does non-BrH SPECT in pulmonary emphysema. DIBrH SPECT-CT fusion images are useful for more accurately localizing affected lungs than morphologic CT alone in this disease.

Automated breath-hold perfusion SPECT/CT fusion images of the lungs.

OBJECTIVE: The purpose of this study was to evaluate the clinical applicability and feasibility of deep-inspiratory breath-hold (DIBrH) perfusion SPECT for improving adverse respiratory motion effects and for accuracy of SPECT/CT image fusion. MATERIALS AND METHODS: Eighty-seven consecutive patients with chronic obstructive pulmonary disease (COPD) (n = 43), acute pulmonary thromboembolism (PTE) (n = 26), and interstitial lung disease (ILD), (n = 18), underwent respiratory-monitored DIBrH SPECT with a dual-headed SPECT system. Two COPD and four acute PTE patients were excluded because of inappropriate scanning due to DIBrH difficulty. DIBrH SPECT was automatically fused with DIBrH CT. Perfusion defect clarity and heterogeneity and SPECT/CT matching were compared between DIBrH SPECT and non-breath-hold SPECT. RESULTS: Compared with non-breath-hold SPECT, DIBrH SPECT significantly enhanced defect clarity in acute PTE (p < 0.0001) and perfusion heterogeneity (coefficient of variations [CV] of pixel counts) in COPD and ILD (p < 0.0001). CV in COPD was also better correlated with lung diffusing capacity for carbon monoxide (p < 0.05). DIBrH SPECT also significantly improved SPECT/CT matching (p < 0.0001), with excellent matching of CT lung internal landmarks and pathology with corresponding defects. Fusion images confirmed wedge-shaped defects extending along specific pulmonary arterial branches in acute PTE and heterogeneous defects associated with airway or lung parenchymal abnormalities in COPD and ILD, with perfusion distribution consistent with lung CT attenuation changes. CONCLUSION: DIBrH SPECT is acceptable for routine application to improve respiratory motion effects and accuracy of SPECT/CT image fusion. Confirmative perfusion-morphologic correlation with reliable fusion images appears useful for clarifying the cause of perfusion defects and abnormal lung CT attenuation.

Respiratory lung motion analysis using a nonlinear motion correction technique for respiratory-gated lung perfusion SPECT images.

OBJECTIVE: This study evaluated the respiratory motion of lungs using a nonlinear motion correction technique for respiratory-gated single photon emission computed tomography (SPECT) images. METHODS: The motion correction technique corrects the respiratory motion of the lungs nonlinearly between two-phase images obtained by respiratory-gated SPECT. The displacement vectors resulting from respiration can be computed at every location of the lungs. Respiratory lung motion analysis is carried out by calculating the mean value of the body axis component of the displacement vector in each of the 12 small regions into which the lungs were divided. In order to enable inter-patient comparison, the 12 mean values were normalized by the length of the lung region along the direction of the body axis. RESULTS: This method was applied to 25 Technetium (Tc)-99m-macroaggregated albumin (MAA) perfusion SPECT images, and motion analysis results were compared with the diagnostic results. It was confirmed that the respiratory lung motion reflects the ventilation function. A statistically significant difference in the amount of the respiratory lung motion was observed between the obstructive pulmonary diseases and other conditions, based on an unpaired Student's t test (P < 0.0001). CONCLUSIONS: A difference in the motion between normal lungs and lungs with a ventilation obstruction was detected by the proposed method. This method is effective for evaluating obstructive pulmonary diseases such as pulmonary emphysema and diffuse panbronchiolitis.

Semi-quantitation of pulmonary perfusion heterogeneity on respiratory-gated inspiratory and expiratory perfusion SPECT in patients with pulmonary emphysema.

OBJECTIVE: Pulmonary perfusion heterogeneity (PPH) in pulmonary emphysema (PE) was semi-quantified by functional lung volume rate (FLVR) curves obtained from respiratory-gated inspiratory and expiratory single-photon emission computed tomography (SPECT). METHODS: Gated and ungated SPECT were obtained in 36 PE patients [25 with stage IIA and 11 with stage IIB for global initiative for chronic obstructive lung disease (GOLD) stage classification] and 12 controls, using a triple-head SPECT system and a respiratory tracking device. On gated SPECT, the voxel numbers calculated at the 10% cutoff threshold for the maximum lung radioactivity were assumed to be the functional lung volume of the lung (V). FLVR (%) was calculated as FLV divided by V at every additional 10% thresholds, yielding inspiratory and expiratory FLVR curves. The dissociations between these curves (DeltaFLVRinsp-exsp) and the total difference (D index) of these curves from the normal standard curve (averaged inspiratory and expiratory curve in controls) were calculated. D index and the extent of low attenuation area (%LAA) on CT were correlated with the transfer coefficient for carbon monoxide (KCO) in PE patients. RESULTS: Although gated and ungated SPECT showed fairly uniform perfusion in controls, gated SPECT-enhanced PPH compared with ungated SPECT in PE patients, with significantly higher dissociation (DeltaFLVRinsp-exsp) than that in controls (24.9%+/-9.5% vs. 4.5%+/-1.3%; P<0.0001). DeltaFLVRinsp-exsp was significantly higher even in stage IIA patients (P<0.0001). Expiratory D index was significantly higher than the inspiratory one in PE patients (P<0.01). This index was significantly higher in stage IIB patients than in stage IIA patients (44.1%+/-19.0% vs. 29.4%+/-13.7%; P<0.05), and was significantly correlated with KCO (R=0.642, P<0.0001) in all PE patients, although %LAA was not correlated with KCO. CONCLUSIONS: FLVR curve analysis on gated SPECT appears useful for semi-quantitation of respiratory change of PPH in PE. Expiratory D index may better reflect the lung pathophysiology of PE than morphologic CT.

Nonlinear motion correction of respiratory-gated lung SPECT images.

We propose a method for correcting the motion of the lungs between different phase images obtained by respiratory-gated single photon emission computed tomography (SPECT). This method is applied to SPECT images that show a preserved activity distribution in the lungs such as 99m-Tc macro aggregated albumin (99m-Tc-MAA) perfusion images and 99m-Tc-Technegas ventilation images. In the proposed method, an objective function, which consists of both the degree of similarity between a reference image and a deformed image, and the smoothness of deformation is defined and optimized using a simulated annealing algorithm. For the degree of similarity term in the objective function, an expansion ratio, defined as the ratio of change in local volume due to deformation, is introduced to preserve the total activity during the motion correction process. This method was applied to data simulated from computer phantoms, data acquired from a physical phantom, and 17 sets of clinical data. In all cases, the motion correction between inspiration and expiration phase images was successfully achieved.

[Development of a new method of high-speed rotation multiplied projection single photon emission computed tomography of the triple-headed type: lung MAA SPECT based on phantom study].

PURPOSE: A chest phantom study was conducted to evaluate the image quality of newly developed high-speed rotation multiplied projection-single photon emission computed tomography (HSRMP-SPECT) images. MATERIALS AND METHODS: HSRMP-SPECT images of a chest phantom consisting of a simulated lung structure filled with 5000 ml of water containing 185 MBq Tc-99m-pertechnetate, and several small 11 mm simulated lung nodules of glass balls and one large 35 mm simulated lung nodule of a plastic sphere filled with water were obtained using a triple-headed SPECT system. During image acquisition, this phantom was regularly moving in the head-to-caudal direction with a range of 12 mm at a frequency of 15 cycles/min to simulate respiratory motion, and 360 degrees projection data of this moving phantom was acquired with an image acquisition time of 20 sec, which was repeated 10 times. To eliminate the setting time between projection and acquisition of multiple temporal samples of data, each detector was continuously rotated in the clockwise direction for 20 sec around a 120-degree arc. On the perspective SPECT images reconstructed from various numbers of the 20-sec projection data, the perfusion heterogeneity of the simulated lungs and perfusion defect clarity of the simulated nodules were assessed by the coefficient of variation (CV) of pixel counts and the defect-to-lung radioactivity ratios, respectively. The results were compared with those on conventional SPECT images of the moving phantom obtained with a data acquisition time of 8 min, and SPECT images of the standing phantom obtained with the same data acquisition time. RESULTS: The average CV value of 0.28+/-0.01 on the SPECT image reconstructed from 5 projection data sets was not significantly different from that of 0.27+/-0.01 on the SPECT image reconstructed from 10 projection data sets (p<0.05). The perfusion defect contrast of the simulated nodules obtained from 5 projection data was significantly higher than that on conventional SPECT images (0.50 vs. 0.73) . CONCLUSIONS: The present phantom study indicated that HSRMP-SPECT could be a useful technique for quickly obtaining high-quality SPECT images of a moving subject, thereby improving perfusion defect clarity in comparison with the conventional technique. This technique may have potential utility for obtaining high-quality breath-hold SPECT images of the chest in clinical practice.

[Examination of three-detector high-speed-rotation SPECT acquisition under breathhold in body: clinical application of 99mTc-MAA].

In traditional pulmonary perfusion single photon emission computed tomography (SPECT), respiratory lung motion and cyclically varying changes in lung volume during image acquisition inherently degrade the image sharpness of ill-defined perfusion defects. However, because of the lack of an adequate fast imaging technique, perfusion SPECT has never been acquired under breathhold conditions, whereas breathhold images are commonly used for pulmonary magnetic resonance (MR) and computed tomographic (CT) images. Although a high-speed imaging technique combined with a multidetector SPECT system may enable SPECT images to be obtained during a short period of breathholding, image quality would be degraded owing to decreased radioactivity counts and increased statistical noise. To resolve this problem, we developed an innovative SPECT imaging technique using a triple-head SPECT system and the high-speed-detector rotation-multiplied projection (HSRMP) technique, where a single SPECT image was reconstructed from multiple respiratory dimensional breathhold projection data obtained at the same angle. HSRMP provided noiseless high-quality perfusion SPECT images by compensating for decreased radioactivity counts caused by high-speed imaging, and significantly improved image quality and perfusion defect clarity compared with traditional non-breathhold SPECT images.