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Objective(s): A simple noninvasive microsphere (SIMS) method using 123I-IMP and an improved brain uptake ratio (IBUR) method using 99mTc-ECD for the quantitative measurement of regional cerebral blood flow have been recently reported. The input functions of these methods were determined using the administered dose, which was obtained by analyzing the time activity curve of the pulmonary artery (PA) for SIMS and the ascending aorta (AAo) for the IBUR methods for dynamic chest images. If the PA and AAo regions of interest (ROIs) can be determined using deep convolutional neural networks (DCNN) for segmentation, the accuracy of these ROI-setting methods can be improved through simple analytical operations to ensure repeatability and reproducibility. The purpose of this study was to develop new PA and AAo-ROI setting methods using a DCNN (DCNN-ROI method).Methods: A U-Net architecture based on convolutional neural networks was used to determine the PA and AAo candidate regions. Images of 290 patients who underwent 123I-IMP RI-angiography and 108 patients who underwent 99mTc-ECD RI-angiography were used. The PA and AAo-ROI results for the DCNN-ROI method were compared to those obtained using manual methods. The counts for the input function on the PA and AAo-ROI were determined by integrating the area under the curve (AUC) counts of the time-activity curve of PA and AAo-ROI, respectively. The effectiveness of the DCNN-ROI method was elucidated through a comparison with the integrated AUC counts of the DCNN-ROI and the manual ROI.Results: The coincidence ratio for the locations of the PA and AAo-ROI obtained using the DCNN method and that for the manual method was 100%. Strong correlations were observed between the AUC counts using the DCNN and manual methods.Conclusion: New ROI- setting programs were developed using a deep convolution neural network DCNN to determine the input functions for the SIMS and IBUR methods. The accuracy of these methods is comparable to that of the manual method.

In this study, we aimed to develop a deep convolutional neural network (DCNN)-based automatic time– activity curve (TAC) fitting method for input function determination. This will be achieved through a comparison between the DCNN method, manual method, and mathematical fitting methods using the expectation maximization algorithm (EM-method) to uncover the potential of the DCNN approach. A U-Net architecture based on convolutional neural networks was used to determine the TAC fittings. The area under the curve (AUC) values of the TAC by the EM and DCNN methods were compared to those obtained using the manual method. The AUC values for the EM-manual method exhibited similarity within an error range of approximately ±20%. Conversely, the error range for DCNN-manual method was approximately ±10%, signifying a reduction in the error range to approximately 1/2. Our findings indicate that the DCNN method provides accuracy equivalent to those of manual methods and even slightly superior to that of the EM method. [ABSTRACT FROM AUTHOR]

Objective: The γ-Ray Evaluation with iodoamphetamine for Cerebral Blood Flow Assessment (REICA) is a new method for quantifying cerebral blood flow (CBF) using single-photon emission computed tomography (SPECT) and [123I]N-isopropyl-p-iodoamphetamine (123I-IMP). The present study aimed to validate the REICA method using data including acetazolamide challenge test.Methods: The REICA and Graph-Plot (GP) methods were used to calculate mean CBF (mCBF) for 92 acquisitions (rest: 57, stress: 35) and cerebrovascular reactivity (CVR) in 33 patients. To obtain stress data, 15 mg/kg of acetazolamide was injected intravenously 10 min before the administration of 123I-IMP, and blood samples were collected under the same conditions as rest data. The reference standard was the Autoradiograph (ARG) method using arterial blood sampling, and the accuracy of the REICA method was analyzed by comparing it with each method.Results: For mCBF, the correlation coefficients (r) were 0.792 for the REICA method and 0.636 for the GP method. For CVR, r values were 0.660 for the REICA method and 0.578 for the GP method. In both acquisitions, the REICA method had a stronger correlation with the ARG method than the GP method. For mCBF, there was a significant difference in the correlation coefficient between the two correlation coefficients (p < 0.01).Conclusions: The REICA method was more accurate than the GP method in quantifying CBF and closer to the ARG method. The REICA method, which is a noninvasive method of cerebral blood flow quantification using 123I-IMP, has great medical usefulness. [ABSTRACT FROM AUTHOR]

Objective: We developed a simple non-invasive I-123-N-isopropyl-p-iodoamphetamine (123I-IMP) quantification method by analyzing chest RI-angiography and single photon emission computed tomography (SPECT) images based on the microsphere model (SIMS method). Theoretically, the SIMS method could be changed to the simple non-invasive ARG (SIARG) method by modifying the integrated washout ratio (WR) to one-point WR. If the regional cerebral blood flow (rCBF) values derived from the SIARG and ARG methods correlate well, the facilities employing the ARG method can easily switch to the SIARG method. The purpose of this study was to develop the SIARG method by modifying the SIMS method and to confirm the feasibility of this method. Methods: The correlation between the input counts of the SIARG method and the blood counts was determined by linear regression analysis. The rCBF values determined by the SIARG method were compared with the values obtained with the ARG and SIMS methods. Results: There was a good linear correlation between the SIARG counts and the arterial blood counts obtained by the ARG method (r = 0.85, p < 0.001, n = 29). TherCBF values obtained by the ARG and SIARG methods (n = 29, 696 ROIs) correlated well (y = 1.01x – 3.6, r = 0.85, p < 0.001). Similarly, the rCBF values obtained by the SIARG and SIMS methods (n = 29, 696 ROIs) correlated well (y = 0.98x – 15.2, r = 0.90, p < 0.001). rCBF values obtained by the SIARG method were almost the same as the values obtained by the ARG method, and values of the SIMS method were 15 ml/100g/min higher that of those obtained by the SIARG method. Conclusions: The rCBF values obtained by the ARG, SIARG, and SIMS methods correlated very well. Therefore, the SIARG method is potentially useful for examinations in routine clinical practice.

Objectives: A simple noninvasive microsphere (SIMS) method using 123 I-IMP and an improved brain uptake ratio (IBUR) method using 99m Tc-ECD for the quantitative measurement of regional cerebral blood flow have been recently reported. The input functions of these methods were determined using the administered dose, which was obtained by analyzing the time activity curve of the pulmonary artery (PA) for SIMS and the ascending aorta (AAo) for the IBUR methods for dynamic chest images. If the PA and AAo regions of interest (ROIs) can be determined using deep convolutional neural networks (DCNN) for segmentation, the accuracy of these ROI-setting methods can be improved through simple analytical operations to ensure repeatability and reproducibility. The purpose of this study was to develop new PA and AAo-ROI setting methods using a DCNN (DCNN-ROI method)., Methods: A U-Net architecture based on convolutional neural networks was used to determine the PA and AAo candidate regions. Images of 290 patients who underwent 123 I-IMP RI-angiography and 108 patients who underwent 99m Tc-ECD RI-angiography were used. The PA and AAo-ROI results for the DCNN-ROI method were compared to those obtained using manual methods. The counts for the input function on the PA and AAo-ROI were determined by integrating the area under the curve (AUC) counts of the time-activity curve of PA and AAo-ROI, respectively. The effectiveness of the DCNN-ROI method was elucidated through a comparison with the integrated AUC counts of the DCNN-ROI and the manual ROI., Results: The coincidence ratio for the locations of the PA and AAo-ROI obtained using the DCNN method and that for the manual method was 100%. Strong correlations were observed between the AUC counts using the DCNN and manual methods., Conclusion: New ROI- setting programs were developed using a deep convolution neural network DCNN to determine the input functions for the SIMS and IBUR methods. The accuracy of these methods is comparable to that of the manual method., Competing Interests: The authors have no relevant financial or non-financial interests to disclose., (© 2024 mums.ac.ir All rights reserved.)

Objective: With the advancement of reperfusion therapy in stroke patients, assessment of perfusion status after therapy is gaining importance. Hyperperfusion tends to be underestimated by the conventional early imaging of 123I-IMP brain perfusion SPECT. We evaluated the utility of super-early imaging as an adjunct to early imaging for the assessment of postischemic hyperperfusion in stroke patients.Methods: Sixty-seven patients who underwent 123I-IMP brain perfusion SPECT within 14 days after the onset of cerebral infarction were retrospectively analyzed. Super-early (4-10 min) and early (15-45 min) images were acquired using a dual-headed gamma camera. Postischemic hyperperfusion was visually assessed using the early images alone and then using both the super-early and early images, and the frequency of postischemic hyperperfusion and the confidence level of the judgement were evaluated. For quantitative evaluation of image contrast, the contrast ratios (the count ratios of the hyperperfused to normal areas) were calculated.Results: The frequency of postischemic hyperperfusion was significantly higher using both the super-early and early images (28/67 patients) than using the early images alone (17/67 patients, p < 0.001). In 56 patients in whom judgement regarding the presence or absence of postischemic hyperperfusion was unchanged, the confidence level was increased in 8 patients using both image sets. The addition of the super-early SPECT images was judged to be useful and marginally useful in 14 and 15 patients, respectively. The contrast ratio was significantly higher on the super-early images (1.48 ± 0.25) than on the early images (1.26 ± 0.18, p < 0.001).Conclusions: The addition of super-early imaging to the conventional early imaging aids assessment of postischemic hyperperfusion by 123I-IMP brain perfusion SPECT and may contribute to management of stroke patients in the era of reperfusion therapy. [ABSTRACT FROM AUTHOR]

I-123-labeled N-isopropyl- p-iodoamphetamine (123I-IMP) is used for the measurement of regional cerebral blood flow (rCBF). A continuous or single arterial blood sampling (ABS) is necessary to estimate an integral of arterial input function (AIF) for the measurement of rCBF by using a microsphere model analysis. Therefore, a method of measuring rCBF without any blood sampling is desired. The aim of this study was to establish a method to estimate the AIF from the time–activity curve of the lungs after an injection of 123I-IMP, using a regression analysis for the measurement of rCBF without any blood sampling. Thirty-seven prospective studies in 10 consecutive patients were enrolled. A chest planar dynamic imaging for 3 min and continuous ABS for 5 min after a bolus injection of 167MBq 123I-IMP were performed in all studies. Data from the chest imaging were analyzed in comparison with ABS data (AIF(5)) in the first 10 studies, and an equation for estimation yielding accurate AIF(5) from the total counts cleared from the lungs, during 5 min after injection of 123I-IMP (TCL(5)), was derived. The validity of the proposed method was evaluated in the subsequent 27 studies. A good correlation was obtained between the AIF and TCL by regression analysis in the first 10 studies ( r = 0.94, P < 0.001). An equation for the estimation of AIF by the regression analysis in the first 10 studies was defined as follows: estimated AIF = 2147 + 4.174 × TCL(5). In the subsequent 27 studies, a good linear correlation was obtained between the measured and the estimated AIF(5) by using the equation ( r = 0.79, P < 0.001). AIF(5) can be accurately estimated from TCL(5). Therefore, estimated AIF(5) can be used for the measurement of rCBF instead of ABS data. [ABSTRACT FROM AUTHOR]

When N-isopropyl-4-iodoamphetamine (123I-IMP) single-photon emission computed tomography (SPECT) studies at rest and after acetazolamide (ACZ) challenge are conducted in a day, the time-dependent change in IMP in the brain at rest should be estimated accurately. We devised the method and investigated whether our one-day method for measuring the rate of increase in SPECT counts allowed reduction in the acquisition time. Sequential, 5-min SPECT scans were performed. We estimated the time-dependent change in the brain using the change in slopes of two linear equations derived from the first three SPECT counts. For the oneday method, ACZ was administered 15 min or 20 min after IMP administration. The second IMP was administered 10 min after ACZ administration. Time-dependent changes in the brain were classified into 13 patterns when estimation was started at 5 min after IMP administration and 6 patterns when estimation was started at 10 min, and fitting coefficients were determined. The correlation between actual measurements at 37.5 min and estimates was high with a correlation coefficient of 0.99 or greater. Rates of increase obtained from 20-min data were highly correlated with those obtained from 15-min or 10-min data ( r = 0.97 or greater). In patients with unilateral cerebrovascular disease, the rate of increase on the unaffected side was 44.4 ± 10.9% when ACZ was administered 15 min later and 48.0 ± 16.0% when ACZ was administered 20 min later, and the rates of increase with different timings of administration were not significantly different. The examination time may be reduced from 50 min to 45 min or 40 min as needed. The rate of increase was not influenced by the time frame for determination or the timing of ACZ administration. These findings suggest that our estimation method is accurate and versatile. [ABSTRACT FROM AUTHOR]

Arterial input function represents the delivery of intravascular tracer to the brain. The optimal setting of this function is essential for measuring regional cerebral blood flow (rCBF) based on the microsphere model using N-isopropyl-4-[123I]iodoamphetamine (123I-IMP), in which the arterial123I-IMP concentration (integral value) during the initial 5 min is usually applied. We developed a novel method in which the arterial123I-IMP concentration is estimated from that in venous blood samples. Brain perfusion SPECT with123I-IMP was performed in 110 patients with disorders of the central nervous system. A causality analysis determined the relationship between various SPECT parameters and the ratio of the octanol-extracted arterial radioactivity concentration during the first 5 min (Caoct) to the octanol-extracted venous radioactivity concentration at 27 min after an intravenous injection of123I-IMP (Cvoct). The Caoct/Cvoct value was estimated using various SPECT parameters and compared with the directly measured value. The measured and estimated values of Caoct/ Cvoct (r = 0.856, n = 50) closely correlated when the following 7 parameters were included in the regression formula: radioactivity concentration in venous blood sampled at 27 min (Cv), Cvoct, Cvoct/Cv, and 4 parameters related to cerebral tissue accumulation that were measured using a four-head gamma camera 5 and 28 min after123I-IMP injection. Furthermore, the rCBF values obtained using the input function estimated by this method also closely correlated with the rCBF values measured using the continuous arterial blood sampling (r = 0.912, n = 180). These results suggest that this method would serve as a convenient and less invasive method of rCBF measurement in the clinical setting. [ABSTRACT FROM AUTHOR]

Unlabelled: The limited spatial resolution of SPECT causes a partial volume effect (PVE) and can lead to the significant underestimation of regional tracer concentration in the small structures surrounded by a low tracer concentration, such as the cortical gray matter of an atrophied brain. The aim of the present study was to determine, using 123I-IMP and SPECT, normal CBF of elderly subjects with and without PVE correction (PVC), and to determine regional differences in the effect of PVC and their association with the regional tissue fraction of the brain.Methods: Quantitative CBF SPECT using 123I-IMP was performed in 33 healthy elderly subjects (18 males, 15 females, 54-74 years old) using the autoradiographic method. We corrected CBF for PVE using segmented MR images, and analyzed quantitative CBF and regional differences in the effect of PVC using tissue fractions of gray matter (GM) and white matter (WM) in regions of interest (ROIs) placed on the cortical and subcortical GM regions and deep WM regions.Results: The mean CBF in GM-ROIs were 31.7 +/- 6.6 and 41.0 +/- 8.1 ml/100 g/min for males and females, and in WM-ROIs, 18.2 +/- 0.7 and 22.9 +/- 0.8 ml/100 g/min for males and females, respectively. The mean CBF in GM-ROIs after PVC were 50.9 +/- 12.8 and 65.8 +/- 16.1 ml/100 g/min for males and females, respectively. There were statistically significant differences in the effect of PVC among ROIs, but not between genders. The effect of PVC was small in the cerebellum and parahippocampal gyrus, and it was large in the superior frontal gyrus, superior parietal lobule and precentral gyrus.Conclusion: Quantitative CBF in GM recovered significantly, but did not reach values as high as those obtained by invasive methods or in the H2(15)O PET study that used PVC. There were significant regional differences in the effect of PVC, which were considered to result from regional differences in GM tissue fraction, which is more reduced in the frontoparietal regions in the atrophied brain of the elderly. [ABSTRACT FROM AUTHOR]

Recently, techniques for converting site-specific normal databases to other databases have been required for SPECT image statistical analysis. To implement scatter correction, we developed an image conversion technique named image-based scatter correction (IBSC). Furthermore, we evaluated the applicability of IBSC for SPM analysis. SPECT studies were performed on 28 normal volunteers and 10 patients with Alzheimer''s disease (AD) using 123I-IMP. Two sets of scatter uncorrected images, IACμb, and a corrected image by TEW, ITEW, were reconstructed with attenuation correction using Chang''s method. Scatter corrected images by IBSC, IIBSC, were generated from IACμb. Normal databases of IACμb, ITEW and IIBSC were compared by SPM analysis. The Z-score (=(mean-AD)/S.D.) of ITEW was compared with that of IACμb. Significant differences (p<0.05) between normal databases of IACμb and ITEW observed at the global posterior cingulate and precuneus regions almost disappeared when ITEW and IIBSC were compared. The Z-score at the posterior cingulate by ITEW was increased compared with that of IACμb. We conclude that for SPM analysis of IMP-SPECT, IBSC can convert a normal database of scatter uncorrected images into corrected images, which is equivalent to correction by a conventional TEW method. Scatter correction may improve the ability to detect AD. [Copyright &y& Elsevier]

The purpose of this study is to characterize the time course of N-isopropyl- p-[123I]-iodoamphetamine (123I-IMP) uptake of primary central nervous system lymphomas (PCNSL) comparing with those of other common brain tumors such as malignant gliomas and meningioma. Ten patients with PCNSL, 14 with malignant gliomas and 7 with meningioma underwent 123I-IMP single photon emission computerized tomography (SPECT). Four (40%), 7 (70%) and 9 cases (90%) of PCNSL showed IMP index more than 1 on early (15min), delayed (6h) and extra-delayed (24h) SPECT images, respectively. In contrast with those IMP index was less than 1 on any image of both malignant gliomas and meningioma. The PCNSL cases with IMP index more than 1 could be distinguished from malignant gliomas and meningioma visually. The mean value of IMP index of PCNSL was increased time-dependently and was higher than those of the other two brain tumor groups on SPECT images of any time phases, and statistically different from those of malignant gliomas, however, not from those of meningioma. Interestingly, the retention rates of 123I-IMP from early to extra-delayed image and delayed to extra-delayed image in PCNSL were significantly higher than those of both malignant gliomas and meningioma. The high 123I-IMP retention on SPECT image is regarded as characteristic in PCNSL and the evaluation of this character is suggested to be more useful for diagnosis of this tumor than that of 123I-IMP up-take on a single SPECT image. [ABSTRACT FROM AUTHOR]

Quantitative crossed cerebellar diaschisis (CCD) and the correlation with a reduction in supratentorial regional cerebral blood flow (rCBF) and cerebrovascular reserve capacity (CVR) were investigated in clinically stable patients with major cerebral artery occlusion by the iodine-123-N-isopropyl-p-iodoamphetamine (I-123 IMP) single photon emission computed tomography (SPECT) method. Thirty patients with major cerebral artery occlusion underwent SPECT by the I-123 IMP autoradiographic method. Regional CBF was measured in the cerebral hemisphere, frontal and parietal lobes, temporo-parietal lobe, and cerebellum both at rest and after administration of acetazolamide. Eighteen of 30 patients (60%) had CCD. CCD was significantly related to magnetic resonance imaging evidence of infarction. Quantitative CCD was 17% and the CVR in the cerebellum was preserved in patients with CCD. There was a significant difference in CBF and CVR between the affected and normal sides in all regions of interest in the patients without CCD [CBF (ml/100 g/min): hemisphere (H), normal side (N): 31.4 +/- 6.8, affected side (A): 27.5 +/- 7.4; p < 0.05. CVR: H, N: 0.56 +/- 0.38, A: 0.42 +/- 0.18; p < 0.01]. CCD is common in patients with major cerebral artery occlusion, and quantitative I-123 IMP SPECT is helpful in detecting CCD in clinically stable patients with occlusion of major cerebral arteries. [ABSTRACT FROM AUTHOR]

Unlabelled: The purpose of this study was to validate a double-injection (DI) method with N-isopropyl-[123I]p-iodoamphetamine (IMP) to measure regional cerebral blood flow (rCBF) twice in a single session of dynamic SPECT and to elucidate a possible role of this method to identify patients with occlusive disease of major cerebral arteries, who might benefit from cerebral revascularization procedures (CR).Materials and Methods: Fourteen patients with occlusion or severe stenosis of the internal carotid or middle cerebral artery were studied before and after CR to assess hemodynamic changes after revascularization treatment. We quantitatively measured rCBF before and after acetazolamide (ACZ) challenge along with cerebrovascular reserve capacity (CVR) with two injections of IMP in a single session of dynamic SPECT scans (DI method). The reliability and reproducibility of the DI method were validated by means of a simulation study and in eight patients who were examined without ACZ challenge to measure baseline rCBF twice.Results: The analysis of simulated noisy data with realistic noise levels showed that the errors of the estimates for the first and the second rCBF and for the increase in rCBF were 2.6%, 8.1% and 10.4%, respectively. In the 8 patients examined by the DI method to measure baseline rCBF twice, the mean and the SD of percentage differences between the two consecutive measurements in rCBF were -1.3% and 5.5%, respectively. Eight out of 14 patients with occlusive disease had at least one region with a CVR less than 10%. They showed a significant increase in resting rCBF after CR, not only in the ipsilateral hemisphere (from 26.1 +/- 6.4 to 33.4 +/- 4.7) but also in the contralateral one (from 28.3 +/- 7.0 to 34.7 +/- 4.7) with a recovery of the ipsilateral CVR from 9.3 +/- 17.2 to 41.2 +/- 20.1%. The remaining six patients with good-moderate CVR did not show an increase in rCBF after CR (from 28.0 +/- 2.7 to 28.3 +/- 3.4). The three of them with a moderate CVR (10-25%) before CR showed normalization of CVR after CR.Conclusion: Patients with decreased rCBF and reduced CVR benefited from CR in terms of an increase in rCBF and recovery of CVR. The quantitative double-injection IMP-SPECT has the ability to identify those patients who may benefit from CR. [ABSTRACT FROM AUTHOR]

Objectives: We developed a simple non-invasive I-123-N-isopropyl-p-iodoamphetamine ( 123 I-IMP) quantification method by analyzing chest RI-angiography and single photon emission computed tomography (SPECT) images based on the microsphere model (SIMS method). Theoretically, the SIMS method could be changed to the simple non-invasive ARG (SIARG) method by modifying the integrated washout ratio (WR) to one-point WR. If the regional cerebral blood flow (rCBF) values derived from the SIARG and ARG methods correlate well, the facilities employing the ARG method can easily switch to the SIARG method. The purpose of this study was to develop the SIARG method by modifying the SIMS method, and to confirm the feasibility of this method., Methods: The correlation between the input counts of the SIARG method and the blood counts was determined by linear regression analysis. The rCBF values determined by the SIARG method were compared with the values obtained with the ARG and SIMS methods., Results: There was a good linear correlation between the SIARG counts and the arterial blood counts obtained by the ARG method (r=0.85, P<0.001, n=29). The rCBF values obtained by the ARG and SIARG methods (n=29, 696 ROIs) correlated well (y=1.01x - 3.6, r=0.85, P<0.001). Similarly, the rCBF values obtained by the SIARG and SIMS methods (n=29, 696 ROIs) correlated well (y=0.98x - 15.2, r=0.90, P<0.001). rCBF values obtained by the SIARG method were almost the same as the values obtained by the ARG method, and values of the SIMS method were 15 ml/100g/min higher that of those obtained by the SIARG method., Conclusion: The rCBF values obtained by the ARG, SIARG, and SIMS methods correlated very well. Therefore, the SIARG method is potentially useful for examinations in routine clinical practice.

Purpose: Our purpose was to identify the causal factors for the perfusion distribution obtained with ASL-MRI by comparing ASL-MRI with clinical information and other MRI findings in moyamoya disease., Methods: Seventy-one patients with moyamoya disease underwent ASL-MRI and other MRI, including fluid-attenuated inversion recovery imaging (FLAIR) and three-dimensional time-of-flight magnetic resonance angiography (MRA) on 3.0-Tesla MRI system. Cerebral blood flow (CBF) values (ASL values) for the cerebral hemispheres (142 sides) were measured on CBF maps generated by ASL-MRI. Relationships between the ASL values and the following 9 factors were assessed: sex, family history, revascularization surgery, age at MR exam, age at onset, the steno-occlusive severity on MRA (MRA score), degree of basal collaterals, degree of leptomeningeal high signal intensity seen on FLAIR, and size of ischemic or hemorrhagic cerebrovascular accident lesion (CVA score)., Results: Patients with a family history had significantly higher ASL values than those without such a history. There were significant negative correlations between ASL values and age at MR exam, MRA score, and CVA score., Conclusions: ASL-MRI may have cause-and-effect or mutual associations with family history, current patient age, size of CVA lesion, and intracranial arterial steno-occlusive severity in Moyamoya disease., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)