Topics of nuclear medicine research in Europe.

Last year in the European Journal of Nuclear Medicine and Molecular Imaging, we introduced some recent nuclear medicine research conducted in Japan. This was favorably received by European readers in the main. This year we wish to focus on the Annals of Nuclear Medicine on some of the fine nuclear medicine research work executed in Europe recently. In the current review article, we take up five topics: prostate-specific membrane antigen imaging, recent advances in radionuclide therapy, [18F]fluorodeoxyglucose positron-emission tomography (PET) for dementia, quantitative PET assessment of myocardial perfusion, and iodine-124 (124I). Just at the most recent annual meeting of the European Association of Nuclear Medicine 2016, Kyoto was selected as the host city for the 2022 Congress of the World Federation of Nuclear Medicine and Biology. We hope that our continuous efforts to strengthen scientific cooperation between Europe and Japan will bring many European friends and a great success to the Kyoto meeting.

Transseptal puncture and catheter ablation via the superior vena cava approach for persistent atrial fibrillation in a patient with polysplenia syndrome and interruption of the inferior vena cava: contact force-guided pulmonary vein isolation.

AIMS: We sought to establish the technical feasibility of transseptal puncture and left atrial (LA) ablation through the right internal jugular vein via the superior vena cava (SVC) approach in patients with an interrupted inferior vena cava (IVC). METHODS AND RESULTS: A 34-year-old man with persistent atrial fibrillation (AF) and polysplenia syndrome (hypoplasia of the left kidney, aplasia of the pancreas tail, bilaterally bilobed lungs, and an interrupted IVC) was referred to our hospital for radiofrequency ablation. Because transseptal puncture and LA ablation would be impossible by a standard IVC approach via the femoral vein, we performed transseptal puncture and LA ablation through the right internal jugular vein via the SVC approach using a manually curved Brockenbrough needle and intracardiac echocardiographic guidance. We accomplished pulmonary vein (PV) isolation using a deflectable guiding sheath and a contact force-sensing ablation catheter to monitor the contact force and the force-time integral of the tip of the ablation catheter. No complications occurred during or after the procedure. The patient was discharged home without recurrence of AF 3 days after the procedure. He had no recurrence of AF and was taking no medication 5 months after ablation. CONCLUSIONS: We successfully performed transseptal puncture in a patient with persistent AF, polysplenia syndrome, and complete interruption of the IVC using the superior route through the internal jugular vein. We also accomplished PV isolation using a deflectable guiding sheath and real-time monitoring of the contact force of the ablation catheter.

Clinical impact of "true whole-body" (18)F-FDG PET/CT: lesion frequency and added benefit in distal lower extremities.

OBJECTIVES: The purpose of this study was to evaluate the lesion frequency and incremental added benefit with "true whole-body" (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) of distal lower extremities. We compared this field of view with the typical whole-body view, from head to upper thighs, in numerous patients with known or suspected malignancy. METHODS: True whole-body (18)F-FDG PET/CT, from the top of the head to the bottom of the feet, was performed on 4574 consecutively registered patients with known or suspected malignancy. Using a variable sampling method, the PET images of head and torso were acquired for 90 s per bed position, and the images of lower extremities were acquired for 30 s per position, thus requiring between 22 and 24 min of emission scanning per patient. A log was maintained to record cases of abnormal findings in distal lower extremities outside the typical whole-body field of view. Suspected malignant lesions in distal lower extremities were verified by correlation with pathological findings and clinical follow-up. RESULTS: Abnormal findings in distal lower extremities were found in 647 (14.1 %; 95 % CI 13.1-15.2 %) of 4574 examinations. Increased FDG uptake was found in 559 examinations (12.2 %; 95 % CI 11.3-13.2 %). Lesions appeared malignant or equivocal in 67 examinations (1.5 %; 95 % CI 1.1-1.8 %) on the PET images. In 42 (0.9 %; 95 % CI 0.6-1.2 %) of 4574 examinations, these lesions were pathologically or clinically proven to be malignant. Detection of these malignancies resulted in changing clinical management in 21 (50 %) of 42 examinations. Definitive benign lesions were found in 492 examinations (10.7 %; 95 % CI 9.9-11.7 %) on the PET images. Abnormal findings were noted in 90 examinations (2.0 %; 95 % CI 1.6-2.4 %) consisting of 88 benign and 2 malignancies on the CT images alone. CONCLUSION: True whole-body (18)F-FDG PET/CT was not of high yield and appears to offer little additional benefit, as to detection of additional metastases and involvement, but it may affect clinical management in patients with known or suspected malignancy.

¹8F-Fluorodeoxyglucose uptake and clinicopathological features of recurrent or metastatic endometrial stromal sarcoma.

AIM: Maximum standardized uptake value on (18) F-fluorodeoxyglucose positron emission tomography was evaluated as a predictive surrogate marker in developing treatment strategies for recurrent or metastatic endometrial stromal sarcoma. METHODS: Clinical information was obtained from records of patients with recurrent or metastatic endometrial stromal sarcoma who underwent surgery or biopsy following (18)F-fluorodeoxyglucose positron emission tomography. Pathological features - including estrogen receptor, progesterone receptor and Ki-67 expression - were immunohistochemically evaluated. We classified lesions as 'positron emission tomography positive' if the maximum standardized uptake value was 3.0 or higher. Clinicopathological features were compared between patients with positive and negative positron emission tomography findings by using the χ(2)-test. RESULTS: Among eight recurrent and one metastatic endometrial stromal sarcoma patients, four (44%) had positron emission tomography-positive findings. Two positron emission tomography-positive patients were estrogen receptor negative and the five positron emission tomography-negative patients were estrogen receptor positive (P = 0.073). The Ki-67 index was 10% or higher in the four positron emission tomography-positive patients, but less than 5% in the five positron emission tomography-negative patients (P = 0.003). Three patients with positron emission tomography-positive tumors received more aggressive treatment (e.g. cytotoxic chemotherapy and additional surgery) than did those with positron emission tomography-negative tumors. One patient who died of disease had positron emission tomography-positive tumors, was negative for estrogen and progesterone receptors, and had a 20% Ki-67 index. CONCLUSION: (18)F-Fluorodeoxyglucose uptake was associated with tumor biology of recurrent or metastatic endometrial stromal sarcoma. (18)F-fluorodeoxyglucose-positron emission tomography was useful for developing treatment strategies for recurrent or metastatic endometrial stromal sarcoma.

Nuclear neuroimaging in acute and subacute ischemic stroke.

Neuroimaging in ischemic stroke continues to be one of the most developing fields in nuclear medicine. Many studies have established the efficacy of blood flow and metabolism measurements in acute ischemic stroke. Although the release of recombinant tissue plasminogen activator in clinical practice has minimized the use of SPECT or PET in the first few hours of ischemic stroke onset, implementing these techniques into a set of initial examinations is still beneficial to exclude risky patients for reperfusion therapy beyond several hours after onset. Rescuing of viable tissue suffering ischemic penumbra is an important target of early therapeutic strategy. Ischemic penumbra can be visualized by means of perfusion imaging, central type benzodiazepine receptor imaging, and hypoxy imaging. In the later phase of subacute ischemic stroke, inflammation and apoptosis can be visualized by means of peripheral-type benzodiazepine receptor imaging and annexin V imaging, respectively. Imaging of the penumbra and cellular responses will help evaluate the effects of drugs and interventions for ischemic stroke, suggesting its potential as a marker of the efficacy of future therapeutic regimens.

Blood pressure lowering with valsartan is associated with maintenance of cerebral blood flow and cerebral perfusion reserve in hypertensive patients with cerebral small vessel disease.

BACKGROUND: The purpose of this study was to determine the effect of systemic blood pressure-lowering treatment with an angiotensin II receptor blocker, valsartan, on cerebral hemodynamics in patients with hypertension and evidence of cerebral small vessel disease. METHODS: We used positron emission tomography and acetazolamide challenge tests to measure cerebral blood flow (CBF) and cerebrovascular reserve (CVR) in 8 patients with hypertension (mean age 70.8 years) with lacunar infarcts and white matter lesions before and after valsartan therapy. RESULTS: Systemic blood pressure was significantly decreased from baseline after treatment with valsartan. The baseline global CBFs before and after treatment were 38.2 +/- 5.6 mL/min/100 g and 39.9 +/- 9.0 mL/min/100 g, respectively. The CVRs before and after treatment were 52.2 +/- 18.4% and 39.7 +/- 18.9%, respectively. Differences in these parameters were not significant. Both regional CBF and CVR in the corona radiata with moderate or severe white matter lesions were also preserved after valsartan therapy compared with those before treatment. CONCLUSIONS: Cerebral hemodynamics were preserved after blood pressure lowering with valsartan therapy. Valsartan could be a feasible antihypertensive regimen in terms of cerebral circulation in patients with cerebral small vessel disease.

[Clinical utility of PET-CT for esophageal cancer].

It is important to diagnose the exact clinical staging according to the improvement of treatment for esophageal cancer. PET examinations for esophageal cancer are now covered by Japanese government health insurance, so the number of PET scans is now gradually increased in many institutions and their utility has been reported. In this report, we reviewed the conventional diagnostic tools for esophageal cancer and evaluated the clinical significance of PET-scans conventionally associated with it. The depth of tumor invasion of a primary tumor is detectable in more than 80% of cases of SM2 or deeper invasion. With lymph node metastasis, the sensitivity was 66. 7% and specificity 93. 5%. With distant metastasis, there is reportedly a high detection rate in bone metastasis and liver metastasis. However, with lung metastasis, reference to CT scans rather than PETscans is important in making a carefull diagnosis. In judging the effect of preoperative chemoradiotherapy, PET-CT was suggested to be an effective diagnostic tool. In addition, PET may be a useful diagnostic tool for postoperative follow-up patients. Finally, further investigation may well be necessary in the future.

Relationship between cerebral blood flow and later cognitive decline in hypertensive patients with cerebral small vessel disease.

Vascular risk factors are thought to be important for dementia. However, there is little evidence for a prospective association between cerebral blood flow and the risk of cognitive decline. Twenty-seven cognitively intact hypertensive patients aged 55 years and older with lacunar infarction or white matter lesions in magnetic resonance imaging (MRI) underwent positron emission tomography (PET) to measure cerebral blood flow (CBF) and cerebral vascular reactivity (CVR). Cognitive function was assessed at baseline and 3 years later with the mini-mental state examination (MMSE). Patients whose MMSE score fell by more than three points were classified as having cognitive decline. Six patients showed cognitive decline. Baseline CBF in these patients was significantly lower than that of the 21 patients without cognitive decline (31.2+/-2.4 vs. 42.6+/-5.9 ml per 100 g min(-1), respectively; P<0.001). A moderate linear association was found between CBF and change in MMSE score over a 3-year period (r=0.59, P=0.001), not between CBF and baseline MMSE score. In contrast, no association between CVR and later cognitive decline was found. This study suggests that cerebral hypoperfusion is associated with later cognitive decline.

Functional brain areas associated with manipulation of a prehensile tool: a PET study.

Using PET, brain areas representing the use of a well-learned tool (chopsticks) were investigated in 10 normal common users. The experimental task was to hold the tool in their right hand and use it to pick up and transport a small pin from a table. Data for the same task performed using only the fingers were also obtained as a control. The results showed an extensive overlap in activated areas with and without the use of the tool. The tool-use prehension, compared to the finger prehension, was associated with higher activities in the caudal-ventral premotor, dorsal premotor, superior parietal, posterior intraparietal, middle temporal gyrus, and primary sensory, occipital cortices, and the cerebellum. These are thus considered to be the human cortical and subcortical substrates representing the use of the tool studied. The activity of the posterior intraparietal area was negatively correlated with the number of drops of the pin, whereas occipital activity was positively correlated with the same error parameter. The caudal-ventral premotor and posterior intraparietal areas are together known to be involved in tool use-related modulation in peripersonal space. The correlation results suggest that this modulation depends on the level of performance. The coactivated left middle temporal gyrus further suggests that familiarity with a tool as well as the knowledge about its usage plays a role in peripersonal space modulation. Superior parietal activation, along with occipital activation, indicates the involvement of visual-spatial attention in the tool use, possibly reflecting the effect of interaction between the prehension (task) and the tool.

Statistical parametric analysis of cerebral blood flow in vascular dementia with small-vessel disease using Tc-HMPAO SPECT.

BACKGROUND: Subcortical ischemic vascular dementia (SVD) caused by small-artery disease is a major cause of dementia. It still remains unclear, however, whether SVD may present with localized regional cerebral blood flow (rCBF) changes. We aimed to clarify the local rCBF changes associated with dementia in patients with early-stage SVD. METHODS: The subjects consisted of 15 patients with early-stage SVD [Mini Mental State Examination (MMSE) score: 20 +/- 3.5] without apparent brain atrophy (SVD group), 11 patients without dementia with white matter lesions (non-dementia-WML group) and 16 age-matched controls. All the subjects were right-handed and underwent brain perfusion single photon emission computed tomography (SPECT), magnetic resonance imaging and cognitive function testing. Statistical analysis of the differences in the SPECT rCBF was performed by SPM2. The degree of severity of the WMLs was evaluated based on the Scheltens rating scale. RESULTS: The results of SPM analysis revealed that the rCBF in the SVD group was significantly decreased in the pulvinar nuclei of the thalamus of both sides as compared with that in the controls, and in the left pulvinar nucleus as compared with that in the non-dementia-WML group. On the other hand, SPM analysis revealed no significant reduction in rCBF in the non-dementia-WML group as compared with that in the controls. The WMLs in the left parietal region were severer in the SVD group than in the non-dementia-WML group. CONCLUSIONS: In patients with early-stage SVD without apparent brain atrophy, significant rCBF reduction in the bilateral pulvinar nuclei as compared with that in normal controls, and in the left pulvinar nucleus as compared with that in patients without dementia with WMLs was found.

Cerebral hemodynamics and oxygen metabolism in patients with moyamoya syndrome associated with atherosclerotic steno-occlusive arterial lesions.

BACKGROUND: Patients with major cerebral artery steno-occlusion and the formation of the moyamoya-like vessels associated with some other disorders have been distinguished from moyamoya disease and classified as moyamoya syndrome. The hemodynamic and metabolic backgrounds of the moyamoya syndrome associated with atherosclerosis have not yet been investigated. We aimed to elucidate the hemodynamic and metabolic characteristics associated with the development of basal moyamoya-like vessels in moyamoya syndrome with atherosclerosis. METHODS: Twenty-one patients with chronic unilateral atherosclerotic steno-occlusive lesions of the internal carotid artery or middle cerebral artery (MCA) were enrolled in the study. Based on the angiographic findings, the patients were classified into 2 groups: the moyamoya syndrome group (n = 7) and the non-moyamoya-syndrome group (n = 14). We conducted angiographic evaluations of the extent of the development of basal moyamoya-like vessels in the moyamoya syndrome group. The cerebral blood flow, cerebral metabolic rate of oxygen, oxygen extraction fraction (OEF) and cerebral blood volume were measured using PET in the ipsilateral MCA area in the patients and in normal controls (n = 6). RESULTS: The OEF in the ipsilateral MCA area, except in the basal ganglia, was significantly higher in the moyamoya syndrome group than in the non-moyamoya-syndrome group (p < 0.001). The extent of the development of basal moyamoya-like vessels was closely correlated with the elevation of the OEF (r > 0.999, p < 0.001). CONCLUSION: The basal moyamoya-like vessels are evidence of misery perfusion in patients with unilateral chronic atherosclerotic steno-occlusive lesions of major cerebral artery trunks.

MRI-based correction for partial-volume effect improves detectability of intractable epileptogenic foci on 123I-iomazenil brain SPECT images.

UNLABELLED: (123)I-Iomazenil brain SPECT has been used for the detection of epileptogenic foci, especially when surgical intervention is considered. Although epileptogenic foci exhibit a decrease in (123)I-iomazenil accumulation, normal cerebral cortices often exhibit similar findings because of thin cortical ribbons, gray matter atrophy, or pathologic brain structures. In the present study, we created (123)I-iomazenil SPECT images corrected for gray matter volume using MRI and tested whether the detectability of the epileptogenic foci improved. METHODS: Seven patients (1 male patient and 6 female patients; mean age +/- SD, 34 +/- 17 y) with intractable epilepsy were surgically treated by resecting the cerebral cortex after surface electroencephalography. Histopathologic examination of the resected specimens and a good outcome after surgery indicated that the resected lesions were epileptogenic foci. These patients underwent (123)I-iomazenil SPECT and 3-dimensional T1-weighted MRI examinations before their operations. Each SPECT image was coregistered to the corresponding MR image, and its partial-volume effect (PVE) was corrected on a voxel-by-voxel basis with a smoothed gray matter distribution image. Four nuclear medicine physicians visually evaluated the (123)I-iomazenil SPECT images with and without the PVE correction. The SPECT count ratio of the suspected focus to the contralateral cerebral cortex was evaluated as an asymmetry index (%) based on the volume of interest. RESULTS: The sensitivity, specificity, and accuracy of focus detection by visual assessment were higher after PVE correction (88%, 99%, and 98%, respectively) than before correction (50%, 92%, and 87%, respectively). The mean asymmetry index for the surgically resected lesions was significantly higher on the PVE-corrected SPECT images (22%) than on the PVE-uncorrected ones (16%) (P = 0.006). CONCLUSION: MRI-based PVE correction for (123)I-iomazenil brain SPECT improves the sensitivity and specificity of the detection of cortical epileptogenic foci in patients with intractable epilepsy.

Hemodynamic influences of azelnidipine, a novel calcium channel blocker, on cerebral circulation in hypertensive patients with ischemic white matter lesions.

Calcium channel blockers have been widely used for the treatment of hypertension because several clinical trials have demonstrated their strong action on lowering blood pressure and their role in preventing cardiovascular events such as stroke and coronary heart disease. However, there have been few reports on the effects on cerebral hemodynamics when blood pressure is lowered with this class of drug. In this study, we used positron emission tomography and acetazolamide challenge tests to measure cerebral blood flow and cerebrovascular reserve before and after administration of a novel calcium channel blocker, azelnidipine, in nine hypertensive patients (mean age, 66.1 years) with ischemic white matter lesions. Systemic blood pressure was significantly decreased from baseline (153.8+/-15.5/92.1+/-8.5 mmHg) after treatment with azelnidipine (138.4+/-16.3/81.8+/-6.2 mmHg). The baseline global cerebral blood flow values before and after treatment were 40.1+/-7.2 mL/min/100 g and 39.2+/-8.2 mL/min/100 g, respectively. The cerebrovascular reserve values before and after treatment were 58.6+/-21.7% and 56.3+/-21.3%, respectively. Differences in these parameters were not significant. A regional analysis showed no statistical differences in regional cerebral blood flow or cerebral perfusion reserve throughout the brain before and after treatment. No associations between the decreased blood pressure and the changes in cerebral blood flow or cerebrovascular reserve were found in the whole brain or in the deep white matter with ischemic lesions. In conclusion, we found that the cerebral blood flow and cerebral vascular reserve were preserved after blood pressure lowering with azelnidipine administration in hypertensive patients with ischemic white matter lesions. Azelnidipine, a novel calcium channel blocker, could be a feasible antihypertensive regimen in terms of cerebral circulation in patients with ischemic white matter lesions.

N-isopropyl-4-[123I]iodoamphetamine (123I-IMP) products: a difference in radiochemical purity, unmetabolized fraction, and octanol extraction fraction in arterial blood and regional brain uptake in rats.

N-isopropyl-4-[123I]iodoamphetamine (123I-IMP) is a lipophilic compound utilized for cerebral blood flow (CBF) measurement with single photon emission computed tomography (SPECT). Two different 123I-IMP products (IMP(A) and IMP(B)) are commercially available. We examined the radiochemical purity, unmetabolized fraction, and octanol extraction fraction in arterial blood, and the regional brain uptake of IMP(A) and IMP(B) in a rat model. IMP(B) (96.4% +/- 0.08%, P < 0.05) showed significantly higher radiochemical purity than IMP(A) (95.5% +/- 0.20%). The mean unmetabolized fraction in arterial blood taken at 10 min after intravenous administration of IMP(B) (69.5% +/- 4.4%, P < 0.01) was significantly higher than that of IMP(A) (59.6% +/- 2.6%). The mean octanol extraction fraction of IMP(B) (75.0% +/- 1.3%, P < 0.01) was also significantly higher than that of IMP(A) (67.2% +/- 0.8%). The mean levels of radioactivity in arterial blood sampled at 10 min after injection and mean regional brain radioactivity (cerebral cortices, basal ganglia, brain stem, and cerebellum) at 10-12 min after injection were not significantly different between IMP(A) and IMP(B). The present study indicates differences in the radiochemical purity and the unmetabolized and octanol extraction fraction in arterial blood between the two commercially available 123I-IMP products. The appropriate octanol extraction fractions for IMP(A) and IMP(B) should be determined in humans and employed for quantitative CBF measurement in clinical SPECT.

Differential brain processing of audiovisual sexual stimuli in men: comparative positron emission tomography study of the initiation and maintenance of penile erection during sexual arousal.

The human male psychosexual cycle consists of four phases: excitation, plateau, orgasm, and resolution. Identification of the specific neural substrates of each phase may provide information regarding the brain's pathophysiology of sexual dysfunction. We previously analyzed regional cerebral blood flow (rCBF) with H(2)15O-positron emission tomography (PET) during the excitation phase (initiation of penile erection) induced by audiovisual sexual stimuli (AVSS) and identified activation of the cerebellar vermis, the bilateral extrastriate cortex, and right orbitofrontal cortex, suggesting a role of cognition/emotion in the excitement phase. In the present study, we analyzed rCBF of the same six healthy volunteers during the plateau phase (maintenance of penile erection) induced by AVSS and compared the results with those of the excitation phase. Penile rigidity was monitored in real time with RigiScan Plus during PET scanning. Images were analyzed by statistical parametric mapping (SPM) software, and rCBF in the amygdala, hypothalamus, anterior cingulate, and insula was measured. During the plateau phase, primary subcortical activation was noted in the right ventral putamen, indicating motivational factors in the sexual response via the limbic reward circuit. A significant increase in rCBF in the left hypothalamus was also observed during the plateau phase. The right anterior cingulate and left insula were specifically activated during the excitation phase but not during the plateau phase. These results indicate a significant role of the ventral putamen and the hypothalamus in the plateau phase and confirm that paralimbic and limbic components of the human brain differentially coordinate the sexual response in a psychosexual phase-dependent manner.

Crossed cerebellar diaschisis: a positron emission tomography study with L-[methyl-11C]methionine and 2-deoxy-2-[18F]fluoro-D-glucose.

OBJECTIVE: Crossed cerebellar diaschisis (CCD) is defined as a depression of blood flow and oxidative metabolism of glucose in the cerebellum contralateral to a supratentorial brain lesion, as detected with positron emission tomography (PET) and single photon emission computed tomography. We examined whether L-[methyl-11C]methionine (MET) uptake is affected in CCD. METHODS: In 12 patients with a unilateral supratentorial brain tumor, we evaluated the uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and MET in the cerebellar hemispheres by means of PET. Asymmetry index (AI) was defined as a difference in the average count between the ipsilateral and contralateral cerebellar hemispheres divided by the average count in both cerebellar hemispheres. Patients with AI of FDG PET more than 0.1 and those with AI equal to 0.1 or less than 0.1 were classified as CCD-positive and CCD-negative, respectively. RESULTS: Six patients were CCD-positive and others were CCD-negative in the FDG PET study. Between CCD-positive and CCD-negative patients, mean AI of MET was not significantly different (0.017 +/- 0.023 and 0.014 +/- 0.039, respectively). CONCLUSIONS: Different from glucose metabolism, cerebellar MET uptake was not affected in CCD. The present study may indicate that cerebellar MET uptake is independent of suppression of cerebellar neuronal activity.

Decreased cerebral blood flow and prognosis of Alzheimer's disease: a multicenter HMPAO-SPECT study.

PURPOSE: To determine the usefulness of brain perfusion SPECT for evaluating the severity and progression of Alzheimer's disease (AD). METHODS: Eighty-four AD patients were included. At entry, 99mTc-HMPAO-SPECT, the Mini Mental State Examination (MMSE), Mental Function Impairment Scale (MENFIS), and the Raven Colored Progression Matrix (RCPM) were performed for all 84 patients. During the follow-up periods, two individual MMSE evaluations in 34 patients, two MENFIS evaluations in 30 patients, and two RCPM evaluations in 20 patients were performed. Based on the regions of decreased cerebral blood flow demonstrated on 3D-SSP images of SPECT, the cases were classified as type A (no decrease), type B (decreased blood flow in the parietal or temporal lobe), type C (decreased blood flow in the frontal lobe and parietal or temporal lobe), type Pc (decreased blood flow in posterior cingulate gyrus only), and "other types". The types of decreased blood flow, scores on neuropsychological evaluations, and symptom progression were analyzed. RESULTS: The MENFIS, MMSE, and RCPM scores were poorest in type C patients at entry. The degree of decrease of these scores during the follow-up periods was also greatest in type C. The greatest difference between patients with and without rapid progression in SPECT data of the mild AD patients (MMSE score > or = 24) was in the frontal lobe. CONCLUSION: Decreased blood flow in the frontal lobe of AD patients is correlated not only with reduced cognitive function at the time of the evaluation but with rapid progression in the subsequent clinical course.

[Evaluation of the product-specific standard input function for the IMP-ARG method].

To confirm the previous reports demonstrating the difference in the octanol extraction fractions between the currently available two N-isopropyl-4-iodoamphetamine (123I) products (IMP(A) and IMP(B)), we newly developed the standard input function for IMP(B) in 19 healthy volunteers and compared it with the established standard input function, which has been originally generated with IMP(A). The octanol extraction fractions of IMP(B) were stable from 5 minutes to 16 minutes post injection and significantly higher than those of IMP(A). The mCBFs calculated with IMP(B) by using the established standard input function for IMP(A) tended to be higher than those with the combination of IMP(A) and the established standard input function though the difference was not significant. When measured with IMP(B) combined with the correspondent standard input function, mCBFs were identical to those calculated with IMP(A) with the established standard input function, suggesting that the appropriate standard input function should be used according to the product used.

Effect of linearization correction on statistical parametric mapping (SPM): a 99mTc-HMPAO brain perfusion SPECT study in mild Alzheimer's disease.

OBJECTIVE: Statistical parametric mapping (SPM) was employed to investigate the regional decline in cerebral blood flow (rCBF) as measured by 99mTc-hexamethyl propylene amine oxime (HMPAO) single photon emission computed tomography (SPECT) in mild Alzheimer's disease (AD). However, the role of the post reconstruction image processing on the interpretation of SPM, which detects rCBF pattern, has not been precisely studied. We performed 99mTc-HMPAO SPECT in mild AD patients and analyzed the effect of linearization correction for washout of the tracer on the detectability of abnormal perfusion. METHODS: Eleven mild AD (NINCDS-ADRDA, male/female, 5/6; mean+/-SD age, 70.6+/-6.2 years; mean+/-SD mini-mental state examination score, 23.9+/-3.41; clinical dementia rating score, 1) and eleven normal control subjects (male/female, 4/7; mean+/-SD age, 66.8+/-8.4 years) were enrolled in this study. 99mTc-HMPAO SPECT was performed with a four-head rotating gamma camera. We employed linearization uncorrected (LU) and linearization corrected (LC) images for the patients and controls. The pattern of hypoperfusion in mild AD on LU and LC images was detected by SPM99 applying the same image standardization and analytical parameters. A statistical inter image-group analysis (LU vs. LC) was also performed. RESULTS: Clear differences were observed between the interpretation of SPM with LU and LC images. Significant hypoperfusion in mild AD was found on the LU images in the left posterior cingulate gyrus, right precuneus, left hippocampus, left uncus, and left superior temporal gyrus (cluster level, corrected p < 0.005). With the LC images, significant hypoperfusion in AD was found only in the bilateral posterior cingulate gyrus and left precuneus (cluster level, corrected p < 0.005). A pattern of greater rCBF distribution at the high flow cortices and low flow cortices was observed on LC and LU images, respectively, in the case of both controls and mild AD patients. CONCLUSION: Hippocampal hypoperfusion could be detected by means of SPM in the LU images but not in the LC images. The results of SPM may vary in 99mTc-HMPAO SPECT with or without linearization correction, which should be carefully evaluated when interpreting the pattern of rCBF changes in mild Alzheimer's disease.

Brain processing of audiovisual sexual stimuli inducing penile erection: a positron emission tomography study.

PURPOSE: Penile erection is dependent on commands from the central nervous system. Although basic studies of animals and neuroimaging studies of humans have been conducted to identify key brain regions associated with sexual arousal, to our knowledge no reliable studies of the first excitation phase of sexual arousal leading to penile erection have been reported. MATERIALS AND METHODS: We used H(2)(15)O-positron emission tomography to analyze regional cerebral blood flow just before penile erection in heterosexual volunteers. The subjects viewed 3 different types of audiovisual materials-sexually explicit clips, nonsexual neutral clips and dynamic mosaic image control clips-presented in random order, and penile rigidity was monitored in real time with a RigiScan(R) Plus device. Positron emission tomography scanning was initiated simultaneously when each clip was started, and images obtained when the subjects showed appropriate penile response were analyzed and compared. RESULTS: The advanced audiovisual cortices and cerebellar vermis in the right hemisphere were activated for sexually explicit-dynamic mosaic image control clip contrast, and only the right middle frontal gyrus was activated for sexually explicit- nonsexual neutral clip contrast. Several primary visual and audio regions were activated for dynamic mosaic image control-sexually explicit clip contrast and nonsexual neutral-sexually explicit clip contrast. CONCLUSIONS: We speculate that advanced audiovisual activity with imagination, not primary visual and audio activity, occurs when men experience sexual arousal inducing penile erection. Furthermore, the cerebellar vermis may be a key region for induction of penile erection in humans.