MM2-type sporadic Creutzfeldt-Jakob disease: new diagnostic criteria for MM2-cortical type.

OBJECTIVE: To clinically diagnose MM2-cortical (MM2C) and MM2-thalamic (MM2T)-type sporadic Creutzfeldt-Jakob disease (sCJD) at early stage with high sensitivity and specificity. METHODS: We reviewed the results of Creutzfeldt-Jakob disease Surveillance Study in Japan between April 1999 and September 2019, which included 254 patients with pathologically confirmed prion diseases, including 9 with MM2C-type sCJD (MM2C-sCJD) and 10 with MM2T-type sCJD (MM2T-sCJD), and 607 with non-prion diseases. RESULTS: According to the conventional criteria of sCJD, 4 of 9 patients with MM2C- and 7 of 10 patients with MM2T-sCJD could not be diagnosed with probable sCJD until their death. Compared with other types of sCJD, patients with MM2C-sCJD showed slower progression of the disease and cortical distribution of hyperintensity lesions on diffusion-weighted images of brain MRI. Patients with MM2T-sCJD also showed relatively slow progression and negative results for most of currently established investigations for diagnosis of sCJD. To clinically diagnose MM2C-sCJD, we propose the new criteria; diagnostic sensitivity and specificity to distinguish 'probable' MM2C-sCJD from other subtypes of sCJD, genetic or acquired prion diseases and non-prion disease controls were 77.8% and 98.5%, respectively. As for MM2T-sCJD, clinical and laboratory features are not characterised enough to develop its diagnostic criteria. CONCLUSIONS: MM2C-sCJD can be diagnosed at earlier stage using the new criteria with high sensitivity and specificity, although it is still difficult to diagnose MM2T-sCJD clinically.

Arterial transit artifacts observed by arterial spin labeling in Moyamoya disease.

OBJECTIVES: Arterial spin labeling (ASL) is a magnetic resonance imaging (MRI) technique used to assess cerebral perfusion. When tissue perfusion is impaired, such as in Moyamoya disease, a hyperintense band called the arterial transit artifact (ATA) may occur, which interferes with accurate measurements on ASL-MRI. In this study, we evaluated the correlation of ATAs with magnetic resonance angiography (MRA) and single-photon emission computed tomography (SPECT) imaging results in Moyamoya disease. The aim of our study was to elucidate the pathophysiology of ATAs and risk factors for high ATA scores. MATERIALS AND METHODS: This retrospective study included 28 patients (56 hemispheres) with Moyamoya disease treated at our institution. MRI, MRA, ASL perfusion, and N-isopropyl-[123I] b-iodoamphetamine (123I-IMP) SPECT were performed. In order to semi-quantitatively evaluate the degree of ATA, the ATA scores were measured according to the number of hyperintense signal bands in the cerebral cortex. The relationship between the ATA scores and clinical and radiological factors were analyzed. RESULTS: Regional cerebral blood flow (rCBF) determined with ASL weakly correlated with that determined by 123I-IMP SPECT (ρ=0.31, p=0.027). There was no significant association between the ATA scores and rCBF values determined with 123I-IMP SPECT (p=0.872, 0.745, 0.743 at PLD1000 (post-labeling delay), 1500, and 2000, respectively). However, there was a significant correlation between ATA scores and MRA scores (ρ=0.427 p=0.001; ρ=0.612 p=0.001; ρ=0.563 p=0.001 at PLD1000, 1500, and 2000, respectively). An analysis of patient background characteristics revealed a significantly higher incidence of high ATA scores in female patients, patients with high MRA scores, and patients with a distinguishable ivy sign. A multivariate analysis confirmed that female sex, high MRA score, and presence of an ivy sign were risk factors for high ATA scores. CONCLUSION: ATA scores were moderately correlated with MRA scores, and presence of an ivy sign was the most predictive factor for high ATA scores. A high ATA score determined using ASL in a patient with Moyamoya disease might suggest an advanced disease stage and a reduction in cerebrovascular reserve capacity.

Significance of Quantitative Cerebral Blood Flow Measurement in the Acute Stage after Revascularization Surgery for Adult Moyamoya Disease: Implication for the Pathological Threshold of Local Cerebral Hyperperfusion.

OBJECTIVE: Superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis is a standard surgical procedure for adult patients with moyamoya disease (MMD) and plays a role in preventing ischemic and/or hemorrhagic stroke. Cerebral hyperperfusion (CHP) syndrome is a potential complication of this procedure that can result in deleterious outcomes, such as delayed intracerebral hemorrhage, but the exact threshold of the pathological increase in postoperative cerebral blood flow (CBF) is unclear. Thus, we analyzed local CBF in the acute stage after revascularization surgery for adult MMD to predict CHP syndrome under modern perioperative management. MATERIALS AND METHODS: Fifty-nine consecutive adult MMD patients, aged 17-66 years old (mean 43.1), underwent STA-MCA anastomosis with indirect pial synangiosis for 65 affected hemispheres. All patients were perioperatively managed by strict blood pressure control (systolic pressure of 110-130 mm Hg) to prevent CHP syndrome. Local CBF at the site of anastomosis was quantitatively measured using the autoradiographic method by N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography 1 and 7 days after surgery, in addition to the preoperative CBF value at the corresponding area. We defined CHP phenomenon as a local CBF increase over 150% compared to the preoperative value. Then, we investigated the correlation between local hemodynamic change and the development of CHP syndrome. RESULTS: After 65 surgeries, 5 patients developed CHP syndrome, including 2 patients with delayed intracerebral hemorrhage (3.0%), 1 with symptomatic subarachnoid hemorrhage (1.5%), and 2 with focal neurological deterioration without hemorrhage. The CBF increase ratio was significantly higher in patients with CHP syndrome (270.7%) than in patients without CHP syndrome (135.2%, p = 0.003). Based on receiver operating characteristic analysis, the cutoff value for the pathological postoperative CBF increase ratio was 184.5% for CHP syndrome (sensitivity = 83.3%, specificity =  94.2%, area under the curve [AUC] value  =  0.825) and 241.3% for hemorrhagic CHP syndrome (sensitivity =  75.0%, specificity =  97.2%, AUC value  =  0.742). CONCLUSION: Quantitative measurement of the local CBF value in the early postoperative period provides essential information to predict CHP syndrome after STA-MCA anastomosis in patients with adult MMD. The pathological threshold of hemorrhagic CHP syndrome was as high as 241.3% by the local CBF increase ratio, but 2 patients (3.0%) developed delayed intracerebral hemorrhage in this series that were managed following the intensive perioperative management protocol. Thus, we recommend routine CBF measurement in the acute stage after direct revascularization surgery for adult MMD and satisfactory blood pressure control to avoid the deleterious effects of CHP.

Anterior Choroidal Artery Infarction Evaluated with 123I-Imp Single-Photon Emission Computed Tomography and 7 Tesla Magnetic Resonance Imaging.

Anterior choroidal artery (AchA) infarction remains a challenging diagnosis although it was first described almost 100 years prior. N-isopropyl-p-[123I]-iodoamphetamine single-photon emission computed tomography (123I-IMP SPECT) and 7 Tesla magnetic resonance angiography (7T-MRA) are not routinely performed in cases of AchA infarction. Therefore, the application of 123I-IMP SPECT and 7T-MRA for AchA infarction has not been reported previously. A 67-year-old man presented with disturbed consciousness, gaze preference to the left, aphasia, right homonymous hemianopia, and right hemiparesis. Brain magnetic resonance imaging revealed infarction of the left posterior limb of the internal capsule. Left middle cerebral artery was clearly seen on MRA. However, 123I-IMP SPECT on day 13 showed cortical hypoperfusion which indicated thalamus involvement with neural deactivation. Additionally, 7T-MRA on day 15 revealed an intact left AchA suggesting reperfusion. The neurological deficits improved gradually after treatment and rehabilitation. This case demonstrates AchA infarction with cortical hypoperfusion associated with thalamus involvement, which was clarified by performing 123I-IMP SPECT and 7T-MRA. Perfusion analysis and evaluation of detailed vascular anatomy in stroke can be expected to elucidate pathological conditions.

Biphasic Development of Focal Cerebral Hyperperfusion After Revascularization Surgery for Adult Moyamoya Disease Associated With Autosomal Dominant Polycystic Kidney Disease.

BACKGROUND: Cerebral hyperperfusion (CHP) syndrome is a potential complication of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease (MMD), but its biphasic and delayed development is extremely rare. CASE REPORT: A 47-year-old woman with autosomal dominant kidney disease (ADPKD) presented with transient ischemic attacks due to MMD, and underwent left STA-MCA anastomosis. N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography (123IMP-SPECT) 1 day after surgery revealed asymptomatic CHP at the site of anastomosis. Strict blood pressure control and minocycline hydrochloride relieved CHP at postoperative day 7. However, 2 days later, the patient complained of sensory aphasia, and 123IMP-SPECT demonstrated significant focal CHP at the site of anastomosis accompanying high-intensity signal on magnetic resonance (MR) imaging of fluid attenuated inversion recovery (FLAIR) in her left temporal lobe near the site of anastomosis. We continued strict blood pressure control and additionally administered free radical scavenger (Edaravone) and antiepileptic agents, which gradually improved sensory aphasia. MR imaging and 123IMP-SPECT also confirmed the amelioration of the FLAIR-high lesion and focal CHP in her left temporal lobe. Two months later, the patient underwent right STA-MCA anastomosis without complications. CONCLUSIONS: Although the underlying mechanism is unknown, biphasic development of focal CHP after revascularization surgery in an MMD patient with ADPKD is unique. Due to the potential vulnerability of the systemic vessels in ADPKD, it is conceivable that intrinsic vascular wall fragility in MMD could be enhanced by ADPKD and have partly led to this rare complication.

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.

A Case of Transient Global Amnesia with Small Left Putamen Infarction.

A 67-year-old right-handed woman experienced a sudden anterograde and retrograde short-term memory deficit that recovered on the next day. Magnetic resonance imaging (MRI) showed a spotty high-intensity lesion in the left putamen in the diffusion-weighted and fluid-attenuated inversion recovery images. Transient global amnesia due to lacunar infarction of the left putamen was diagnosed. Transient global amnesia is characterized by a sudden onset of anterograde amnesia that disappears within 24 hours. The cause of transient global amnesia is still uncertain. Some studies with MRI showed small lesions in the hippocampus at 24-74 hours after the episode. These lesions disappear within several weeks. However, our case of transient global amnesia showed a small lesion in the left putamen, not the hippocampus. Some studies with functional MRI reported that the stratum plays an important role in short-term memory and cognitive function. This case showed only a left putamen lesion, which indicates that a putamen lesion can cause transient global amnesia.

A preliminary feasibility study of simultaneous dual-isotope imaging with a solid-state dedicated cardiac camera for evaluating myocardial perfusion and fatty acid metabolism.

Simultaneous dual-isotope SPECT imaging with 201Tl and (123)I-ß-methyl-p-iodophenylpentadecanoic acid (BMIPP) is used to study the perfusion-metabolism mismatch. It predicts post-ischemic functional recovery by detecting stunned myocardium. On the other hand, (99m)Tc-MIBI is another radioisotope widely used in myocardial perfusion imaging because of its better image quality and lower radiation exposure than 201Tl. However, since the photopeak energies of (99m)Tc and (123)I are very similar, crosstalk hampers the simultaneous use of these two radioisotopes. To overcome this problem, we conducted simultaneous dual-isotope imaging study using the D-SPECT scanner (Spectrum-Dynamics, Israel) which has a novel detector design and excellent energy resolution. We first conducted a basic experiment using cardiac phantom to simulate the condition of normal perfusion and impaired fatty acid metabolism. Subsequently, we prospectively recruited 30 consecutive patients who underwent successful percutaneous coronary intervention for acute myocardial infarction, and performed (99m)Tc-MIBI/(123)I-BMIPP dual-isotope imaging within 5 days after reperfusion. Images were interpreted by two experienced cardiovascular radiologists to identify the infarcted and stunned areas based on the coronary artery territories. As a result, cardiac phantom experiment revealed no significant crosstalk between (99m)Tc and (123)I. In the subsequent clinical study, (99m)Tc-MIBI/(123)I-BMIPP dual-isotope imaging in all participant yielded excellent image quality and detected infarcted and stunned areas correctly when compared with coronary angiographic findings. Furthermore, we were able to reduce radiation exposure to significantly approximately one-eighth. In conclusion, we successfully demonstrated the practical application of simultaneous assessment of myocardial perfusion and fatty acid metabolism by (99m)Tc-MIBI and (123)I-BMIPP using a D-SPECT cardiac scanner. Compared with conventional (201)TlCl/(123)I-BMIPP dual-isotope imaging, the use of (99m)Tc-MIBI instead of (201)TlCl improves image quality as well as lowers radiation exposure.

Arterial Spin Labeling Perfusion Magnetic Resonance Image with Dual Postlabeling Delay: A Correlative Study with Acetazolamide Loading (123)I-Iodoamphetamine Single-Photon Emission Computed Tomography.

BACKGROUND: Perfusion magnetic resonance image with arterial spin labeling (ASL) provides a completely noninvasive measurement of cerebral blood flow (CBF). However, arterial transient times can have a marked effect on the ASL signal. For example, a single postlabeling delay (PLD) of 1.5 seconds underestimates the slowly streaming collateral pathways that maintain the cerebrovascular reserve (CVR). To overcome this limitation, we developed a dual PLD method. SUBJECTS AND METHODS: A dual PLD method of 1.5 and 2.5 seconds was compared with (123)I-iodoamphetamine single-photon emission computed tomography with acetazolamide loading to assess CVR in 10 patients with steno-occlusive cerebrovascular disease. RESULTS: In 5 cases (Group A), dual PLD-ASL demonstrated low CBF with 1.5-second PLD in the target area, whereas CBF was improved with 2.5-second PLD. In the other 5 cases (Group B), dual PLD-ASL depicted low CBF with 1.5-second PLD, and no improvement in CBF with 2.5-second PLD in the target area was observed. On single-photon emission computed tomography, CVR was maintained in Group A but decreased in Group B. CONCLUSIONS: Although dual PLD methods may not be a completely alternative test for (123)I-iodoamphetamine single-photon emission computed tomography with acetazolamide loading, it is a feasible, simple, noninvasive, and repeatable technique for assessing CVR, even when employed in a routine clinical setting.

New Regression Equation for 123I-IMP Non-invasive Cerebral Blood Flow Measurement Using the Graph Plot Method.

PURPOSE: A graph plot (GP) method using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) has been proposed as a simple and non-invasive estimation of quantitative cerebral bloodflow (CBF). A regression equation for the GP method was estimated by the data of resting state. Therefore, the accuracy of CBF values in high flow range may be an underestimated possibility in this method.The aim of this study was to formulate a new regression equation for the GP method by the data of resting state and acetazolamide (ACZ) challenge, and to clarify the accuracy of it. METHODS: The images of 26 consecutive patients who underwent both 123I-IMP chest radioisotope-angiography (RIA) and single photon emission computed tomography (SPECT) examinations were used to construct the new regression equation. Examinations of the resting state and ACZ challenge were performed in different days. All patients were analyzed by both the GP method and autoradiography (ARG) method which is the conventional examination with the one-point arterial blood sampling. A linear regression equation between the index of the input function was obtained by the GP method and CBF value of ARG. The linear regression equation based on the resting data was compared with the equation based on the resting and ACZ challenge (rest+stress) data. RESULTS: Goodliner correlation was obtained between the index of the input function obtained by the GP method and CBF value of the ARG method in the rest+stress state (y=2.75x+15.1, r=0.78). In contrast, correlation results between the index of the input function obtained by the GP method and CBF value of the ARG method in the resting state was expressed as y=2.28x+18.4, r=0.54 rCBF values based on the resting data was 20% underestimated in the high flow range compared with values based on the rest+stress data. CONCLUSION: The new linear regression equation for the GP method is useful for clinical study. Key words: non-invasive cerebral blood flow measurement method, graph plot (GP), autoradiography (ARG), 123I-N-isopropyl-p-iodoamphetamine (123I-IMP).

Pathophysiological decrease in the regional cerebral blood flow in Hashimoto's encephalopathy: a multiple-case SPECT study.

BACKGROUND: The aim of this study was to evaluate the changes in regional cerebral blood flow (rCBF) in multiple cases of Hashimoto's encephalopathy (HE). METHODS: Seven untreated patients with HE and 10 age-matched healthy controls underwent brain single photon emission computed tomography (SPECT) with N-isopropyl-p-[(123)I]iodoamphetamine. All patients had anti-NH2-terminal of α-enolase autoantibodies (Abs), which served as a useful diagnostic marker for HE, in addition to anti-thyroid Abs in their sera and responded to corticosteroid therapy. The obtained SPECT images were compared between the patients and the controls using 3D-SSP analysis. RESULTS: The rCBF of all patients with HE was significantly decreased in the bilateral anterior cingulate areas and left prefrontal cortex compared with the controls (p < 0.05). Focusing on the HE patients with acute neuropsychiatric symptoms (n = 5) such as consciousness disturbance and/or psychosis, the decreased rCBF in these areas was more significant, and the rCBF in the right frontal cortex was also decreased. CONCLUSION: Statistical analysis of these multiple-case SPECT images revealed the regions of decreased CBF associated with clinical symptoms, especially acute neuropsychiatric symptoms, in HE patients. This study shed light on the pathophysiological decrease in rCBF observed in HE.

Surgical treatment for carotid stenoses with highly calcified plaques.

BACKGROUND: The aim of this study was to clarify both the present status of treatment for carotid stenosis with highly calcified plaques and the appropriate treatment. METHODS: A total of 140 consecutive treatments for carotid stenoses (carotid endarterectomy [CEA]:carotid artery stenting [CAS] 81:59) were enrolled in the study. We classified the patients into low-calcified plaque (LCP) and high-calcified plaque (HCP) groups by calcium score, determined by a receiver operating characteristic analysis, and we compared the results after both treatments. RESULTS: The mean degree of residual stenosis and improvement rates of the stenosis after CAS for the HCP group were 9.7% ± 13.3% and 87.0% ± 16.8%, respectively, whereas those for the LCP group were 1.7% ± 6.1% and 97.9% ± 7.9% (both P < .001). A multiple logistic regression analysis revealed that only the calcium score was an independent pre-CAS predictor of residual stenosis. Restenosis at 6 months was observed frequently in the HCP group after both CAS and CEA (18.8% and 20.0%, respectively). Cerebral hyperperfusion syndrome was observed in 2 cases of CAS, 1 for each plaque group. The 30-day and 6-month rates for any stroke or death after CAS were 2.3% and 12.5% for the LCP and HCP groups, respectively, whereas those after CEA were 1.6% and 0%. CONCLUSIONS: Carotid stenoses with HCP (calcium score ≥420) treated by CAS showed a disadvantage in the degree of stent expansion compared to carotid stenoses with LCP, suggesting that CEA may be recommended as a surgical option.

[A case of Holmes tremor in which 123I-IMP SPECT and MRI findings suggest damage to the cerebellothalamic tract and the dentato-rubro-olivary pathway].

A 75-year-old woman was referred to our department in October 2022 with ataxia and involuntary movements of the right upper and lower limbs. She had experienced a left pontine hemorrhage in March 2021, which was managed conservatively. However, she had residual right-sided hemiplegia. In addition, she had cerebellar ataxia and a 2 |Hz resting tremor of the right upper and lower limbs, which was enhanced while maintaining posture and contemplation. Based on her history, and the findings of MRI and nuclear medicine imaging, we diagnosed the patient with Holmes tremor due to pontine hemorrhage. Holmes tremor is a rare movement disorder secondary to brainstem and thalamic lesions, characterized by a unilateral low-frequency tremor. In this case, 123I-IMP SPECT and MRI shows damage to the cerebellothalamic tract and dentaro-rubro-olivary pathway.

Neuropsychological deficits associated with destruction of the right nigrostriatal pathway.

Hemiparkinsonism secondary to a vascular mesencephalic lesion is infrequent; these patients offer an exceptional opportunity to study neuropsychological alterations attributable to unilateral dopaminergic denervation, shedding light on the pathophysiology of cognitive disorders in early-stage idiopathic Parkinson's disease (PD). From the investigation of our case, we conclude that destruction of the right nigrostriatal pathway is accompanied by deficits in executive functioning and verbal/visual memory similar to those observed in many patients with early-stage idiopathic PD. The more complex neuropsychological dysfunction developed by other PD patients must therefore be related to the additional involvement of other brain structures.

Changes in clinical management and diagnosis following DaTscan SPECT imaging in patients with clinically uncertain parkinsonian syndromes: a 12-week follow-up study.

BACKGROUND: An accurate diagnosis is important for timely and adequate treatment in patients with clinically uncertain parkinsonian syndrome (CUPS). OBJECTIVE: The objective of this study was to assess safety and changes in clinical management, diagnosis and quality of life (QoL) at 4 and 12 weeks following DaTscan (ioflupane [(123)I] injection) imaging in patients with CUPS. METHODS: This randomized, open-label, single-dose, multicenter trial was carried out in patients with CUPS who were randomized to either a DaTscan imaging group or to a control group without imaging. The main outcome measures were the proportions of patients with changes in clinical management and diagnosis from baseline through to 12 weeks after DaTscan. A total of 19 university hospital centers in Europe and the USA participated in the study. There were 267 patients enrolled and randomized (131 DaTscan, 136 control). RESULTS: Significantly more DaTscan patients had changes in clinical management after 12 weeks (p = 0.004) compared to the control group, and significantly more DaTscan patients had changes in diagnosis at 4 weeks and at 12 weeks (both p < 0.001) compared to control patients. No significant difference in total score for QoL was observed between groups during the study duration. DaTscan was safe and well-tolerated. No deaths, serious adverse events (AEs) or withdrawals due to AEs occurred during the study. One patient had a headache following treatment with a suspected relationship to DaTscan. CONCLUSION: DaTscan imaging significantly affected the clinical management and diagnosis of patients with CUPS. DaTscan is safe and well-tolerated and is a useful adjunct to differential diagnosis of CUPS.

123I-IMP-SPECT in a patient with cerebral proliferative angiopathy: a case report.

Cerebral proliferative angiopathy (CPA) is a new clinical entity demonstrating a diffuse network of densely enhanced vascular abnormalities with intermingled normal brain parenchyma and is distinguishable from classical arteriovenous malformations by specific clinical and imaging markers. However, the pathophysiological nature of this disease is unclear, and there is no consensus on the treatment. We describe cerebral perfusion abnormalities in a patient with CPA by using N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography (123I-IMP-SPECT) and perfusion-weighted magnetic resonance imaging. The patient, a 13-year-old boy, had reversible focal neurological deficits unrelated to cerebral hemorrhage. 123I-IMP-SPECT at resting state showed preserved uptake within the vascular lesion, yet lower uptake in the area adjacent to the lesion. In addition, acetazolamide-stressed 123I-IMP-SPECT exhibited severely impaired cerebrovascular reactivity over the affected hemisphere, suggesting that his focal neurological deficits were related to the cerebral ischemia. The perfusion abnormalities on 123I-IMP-SPECT in a CPA patient have never been previously reported. The concept of vascular malformation-related hypoperfusion is discussed.

Arterial spin-labeling magnetic resonance imaging after revascularization of moyamoya disease.

Arterial spin labeling (ASL) magnetic resonance imaging (MRI) is a technique for depicting cerebral perfusion without contrast medium. The purpose of this study was to determine whether ASL can be used to detect hyperperfusion after revascularization for moyamoya disease as effectively as N-isopropyl-[123I]ß-iodoamphetamine ((123)I-IMP) single-photon emission computed tomography (SPECT). Fifteen consecutive patients with moyamoya disease were included in the study. All patients underwent surgical revascularization. Postoperatively, regional cerebral blood flow (rCBF) was measured by flow-sensitive alternating inversion recovery (FAIR) ASL and (123)I-IMP SPECT during the acute stage, and rCBF of the operative side was compared with the other side. The asymmetry ratio (AR) was then calculated from the rCBF as measured using each modality. The postoperative AR of ASL was moderately correlated with that of (123)I-IMP SPECT (y = 0.180x + 0.819; R = 0.80; P = .0003). In this series, 2 patients (13.3%) suffered symptomatic hyperperfusion after revascularization and accordingly exhibited increased AR of ASL. Our data indicate that early increases in rCBF in patients with hyperperfusion could be detected using FAIR ASL supplemental to (123)I-IMP SPECT after revascularization. Our data indicate that FAIR ASL is a convenient method for evaluating hyperperfusion that can be performed repeatedly without the use of contrast medium or radioisotopes.

[Application of N-isopropyl-p-[123I] iodoamphetamine quantification of regional cerebral blood flow using iterative reconstruction methods: selection of the optimal reconstruction method and optimization of the cutoff frequency of the preprocessing filter].

In cerebral blood flow tests using N-Isopropyl-p-[123I] Iodoamphetamine "I-IMP, quantitative results of greater accuracy than possible using the autoradiography (ARG) method can be obtained with attenuation and scatter correction and image reconstruction by filtered back projection (FBP). However, the cutoff frequency of the preprocessing Butterworth filter affects the quantitative value; hence, we sought an optimal cutoff frequency, derived from the correlation between the FBP method and Xenon-enhanced computed tomography (XeCT)/cerebral blood flow (CBF). In this study, we reconstructed images using ordered subsets expectation maximization (OSEM), a method of successive approximation which has recently come into wide use, and also three-dimensional (3D)-OSEM, a method by which the resolution can be corrected with the addition of collimator broad correction, to examine the effects on the regional cerebral blood flow (rCBF) quantitative value of changing the cutoff frequency, and to determine whether successive approximation is applicable to cerebral blood flow quantification. Our results showed that quantification of greater accuracy was obtained with reconstruction employing the 3D-OSEM method and using a cutoff frequency set near 0.75-0.85 cycles/cm, which is higher than the frequency used in image reconstruction by the ordinary FBP method.

Non-invasive regional cerebral blood flow quantification in the 123I-IMP autoradiography using artificial neural network.

PURPOSE: Regional cerebral blood flow (rCBF) quantification using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) requires an invasive, one-time-only arterial blood sampling for measuring the 123I-IMP arterial blood radioactivity concentration (Ca10). The purpose of this study was to estimate Ca10 by machine learning (ML) using artificial neural network (ANN) regression analysis and consequently calculating rCBF and cerebral vascular reactivity (CVR) in the dual-table autoradiography (DTARG) method. MATERIALS AND METHODS: This retrospective study included 294 patients who underwent rCBF measurements through the 123I-IMP DTARG. In the ML, the objective variable was defined by the measured Ca10, whereas the explanatory variables included 28 numeric parameters, such as patient characteristic values, total injection 123I-IMP radiation dose, cross-calibration factor, and the distribution of 123I-IMP count in the first scan. ML was performed with training (n = 235) and testing (n = 59) sets. Ca10 was estimated in testing set by our proposing model. Alternatively, the estimated Ca10 was also calculated via the conventional method. Subsequently, rCBF and CVR were calculated using estimated Ca10. Pearson's correlation coefficient (r-value) for the goodness of fit and the Bland-Altman analysis for assessing the potential agreement and bias were performed between the measured and estimated values. RESULTS: The r-value of Ca10 estimated by our proposed model was higher compared with the conventional method (0.81 and 0.66, respectively). In the Bland-Altman analysis, mean differences of 4.7 (95% limits of agreement (LoA): -18-27) and 4.1 (95% LoA: -35-43) were observed using proposed model and the conventional method, respectively. The r-values of rCBF at rest, rCBF after the acetazolamide challenge, and CVR calculated using the Ca10 estimated by our proposed model were 0.83, 0.80 and 0.95, respectively. CONCLUSION: Our proposed ANN-based model could accurately estimate the Ca10, rCBF, and CVR in DTARG. These results would enable non-invasive rCBF quantification in DTARG.

Disappearance of hemichorea as the initial presentation of moyamoya disease after revascularization surgery regardless of residual hypoperfusion evaluated by quantitative N-isopropyl-p-123I-iodoamphetamine SPECT.

BACKGROUND AND IMPORTANCE: Although hypoperfusion of the basal ganglia or the frontal subcortical matter is suspected, the pathology of chorea in moyamoya disease remains unclarified. Herein, we report a case of moyamoya disease presenting with hemichorea and evaluate pre- and postoperative perfusion using single photon emission computed tomography with N-isopropyl-p-123I-iodoamphetamine (123I-IMP SPECT). CLINICAL PRESENTATION: An 18-year-old woman presented with choreic movement of her left limbs. Magnetic resonance imaging revealed an ivy sign, and 123I-IMP SPECT demonstrated decreased cerebral blood flow (CBF) and cerebral vascular reserve (CVR) values in the right hemisphere. The patient underwent direct and indirect revascularization surgery to improve cerebral hemodynamic impairment. The choreic movements entirely resolved immediately after surgery. Although CBF and CVR values in the ipsilateral hemisphere demonstrated by quantitative SPECT increased, these did not reach the normal values threshold. CONCLUSION: Choreic movement in moyamoya disease may be related to cerebral hemodynamic impairment. Further studies are required to elucidate its pathophysiological mechanisms.