Nuclear medicine practice in Japan: a report of the sixth nationwide survey in 2007.

OBJECTIVE: The Subcommittee on the Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to provide detailed information on its present status. METHODS: Questionnaires were sent to all institutions known to the Japan Radioisotope Association to conduct nuclear medicine examinations. The questionnaires addressed the number and kind of nuclear medicine examinations performed as well as the kind and dose of the radiopharmaceuticals used during the month of June 2007. The annual number of total or specific examinations was then estimated. RESULTS: Of the institutions sent questionnaires, 1219 were for in vivo study, 49 for in vitro study, and 212 for positron emission tomography (PET) study. Of these, 92.2% provided answers. A total of 1569 gamma cameras were installed in 1119 institutions, of which 70% were dual-head cameras. The estimated total annual number of in vivo examinations expressed by the number of administered radiopharmaceuticals was 1.41 million, representing a decrease of 11.5% when compared with that of the previous survey (2002). The frequency of study with respect to single-photon emission computed tomography (SPECT) slightly increased to 42.3% from 39.9% in the previous survey. The most frequently performed scintigraphy was bone (38.3%), followed by myocardium (26.2%) and brain perfusion (14.1%). Brain perfusion scintigraphy slightly increased, whereas tumor scintigraphy decreased by one-half when compared with the previous survey. The most commonly used radiopharmaceutical for each scintigraphy was (99m)Tc-HMDP for bone, thallium-201 ((201)Tl)-chloride for myocardium, gallium-67 ((67)Ga)-citrate for tumor, and technetium-99m-ethylcysteinate dimmer ((99m)Tc-ECD) for brain. The number of PET institutes increased from 36 to 212. (18)F-fluorodeoxyglucose ((18)F-FDG)-PET dramatically increased 14.8-fold during the past 5 years. Radionuclide therapy also increased. (131)I therapy for thyroid cancer and hyperthyroidism was conducted yearly in 2373 and 4146 patients, respectively. A total of 13.1 million in vitro radioassays were carried out yearly, the number of which has been decreasing continuously since 1992. CONCLUSIONS: It was proved that the content of nuclear medicine practice in Japan has changed considerably in the past 5 years. Namely, (18)F-FDG-PET and radionuclide therapy increased. This report might be useful for understanding the present trends of nuclear medicine practice in Japan.

Correlation between anosognosia and regional cerebral blood flow in Alzheimer's disease.

The purpose of this study was to determine the brain regions associated with anosognosia in Alzheimer's disease (AD). Anosognosia for memory disturbance was assessed in 29 probable AD patients, based on the discrepancy between questionnaire scores of the patients and their caregivers. In I-123-IMP single photon emission computed tomography (SPECT), a significant association was found between anosognosia and decreased perfusion in the orbitofrontal cortex, using regression analysis. This result is consistent with the previous studies that have reported an association between frontal dysfunction and anosognosia, and further suggests that the orbitofrontal cortex specifically associates with anosognosia in AD within the frontal cortex.

Regional cerebral blood flow changes associated with interoceptive awareness in the recovery process of anorexia nervosa.

BACKGROUND: An abnormality in regional cerebral blood flow (rCBF) in anorexia nervosa (AN) patients has been reported. There are very few studies that have investigated the rCBF changes in the recovery process of AN. METHODS: For eight female AN patients, we performed (123)I-IMP single photon emission computed tomography (SPECT) and four psychological assessments (Eating Disorder Inventory (EDI), Eating Attitude Test (EAT), Self-Rating Depression Scale (SDS) and State-Trait Anxiety Inventory (STAI)) both before and after inpatient-behavioral therapy. SPECT images were analyzed using statistical parametric mapping software. We also performed correlational analysis between rCBF and clinical variables. RESULTS: Following treatment, the patients showed significant body weight recovery. They showed significant improvement in EAT, SDS, STAI and a subscale of EDI - interoceptive awareness (IA) - but not in total EDI or other EDI subscales. Significant rCBF increases were observed in the precuneus, posterior cingulate cortex (PCC), right dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC) and medial prefrontal cortex (MPFC) by the treatment. Significant correlation was observed between rCBF of right DLPFC and IA score before treatment. CONCLUSIONS: Changes of rCBF in right DLPFC, ACC, MPFC, PCC and precuneus were related to the AN recovery process and might be associated with improvement of IA following treatment.

A region-of-interest template for three-dimensional stereotactic surface projection images: initial application to the analysis of Alzheimer's disease and mild cognitive impairment.

OBJECTIVE: To construct a region-of-interest (ROI) template for Z-score images of three-dimensional stereotactic surface projections (3-D SSP) and to assess whether the ROI template can be a useful tool for evaluation of brain perfusion abnormalities of neurological disorders. MATERIALS AND METHODS: We constructed the ROI template for Z-score images of 3-D SSP based on the standardized magnetic resonance imaging data of 10 healthy volunteers. We assigned a total of 26 ROIs to Z-score images and superimposed it on Z-score images constructed from the brain perfusion SPECT data of 15 patients with Alzheimer's disease and 10 patients with mild cognitive impairment (MCI) who developed Alzheimer's disease within the following 2 years. We then obtained the mean Z-scores of each ROI and examined them to determine whether the hypoperfusion typical of Alzheimer's disease had been demonstrated quantitatively. We also visually inspected the Z-score image of each patient in both groups to determine whether the areas with the highest Z-scores were demonstrated within the ROIs of regions typical of Alzheimer's disease. RESULTS: In the patients with Alzheimer's disease, our ROI template quantitatively demonstrated hypoperfusion in regions typical of the disease and the Z-scores were very high. In the MCI patients, the mean Z-scores of the ROI in the posterior cingulated gyrus were the highest among all regions. Visual inspection of the Z-score images of each patient in both groups confirmed that the areas with the highest Z-scores were demonstrated within the ROIs in regions typical of Alzheimer's disease in all cases. CONCLUSION: Use of 3-D SSP methods and our ROI template enables automated quantitative evaluation of brain function images over the entire brain surface. In addition, the ROI template may facilitate visual interpretation of functional images of individual patients with neurological disorders.

Age-related changes in the hemodynamics of the femoral head as evaluated by early phase of bone scintigraphy.

OBJECTIVE: The femoral head is reported to be in a markedly hypoemic state as compared with other tissues even under normal conditions, and it is therefore necessary to understand its hemodynamics to investigate the pathogenesis of hip disorders. It is known that aspects of intraosseous hemodynamics including blood flow and blood pool can be evaluated soon after radioisotope administration. In this study, hemodynamic changes in the femoral head according to gender and age were examined by investigating accumulation of radioisotope in the tissue during the early phase of bone scintigraphy. METHODS: The subjects of this study consisted of 58 joints of 31 men and 75 joints of 41 women, whose ages ranged from 15 to 87 years (average age: 67.9 years). Images of bone scintigraphy were obtained for 15 to 20 minutes at 5 minutes and at 3 hours after radioisotope administration. The ratio of accumulation in the femoral head to that in the diaphysis (head-to-diaphysis ratio, HD ratio) was calculated. RESULTS: HD ratios obtained 15-20 minutes later ranged from 0.01 to 7.35 (1.88 +/- 0.91, mean +/- SD). HD ratios decreased with age, and a significant inverse correlation was observed between age and HD ratio, demonstrating a correlation coefficient of -0.27 (p = 0.001). The HD ratio among men was 0.01-3.57 (1.66 +/- 0.71), while that among women was 0.53-7.35 (2.05 +/- 1.01), and a significant difference was observed in HD ratio between men and women (p = 0.02). There was a significant difference in HD ratios between men and women in their teens to forties (p = 0.03), while no significant differences was observed in the other age groups.. HD ratios obtained 3 hours later ranged from 0.44 to 6.32 (1.95 +/- 0.79, mean +/- SD), and no significant correlation was observed between age and HD ratio, demonstrating a correlation coefficient of -0.14. CONCLUSION: The present study demonstrated that blood flow and blood pool of the femoral head decrease with aging particularly in women. This hemodynamic deterioration of the femoral head caused by aging may have an effect on the onset and progression of hip disorders by influencing bone metabolism.

Swyer-James Syndrome in a 7-Year-Old Female.

Swyer-James syndrome is a rare syndrome that occurs as a result of repeated bronchiolitis and pneumonitis in childhood. Most cases are asymptomatic, and subsequent diagnosis may not occur until adulthood. We present the case of a 7-year-old female with Swyer-James syndrome, which was initially diagnosed and treated as asthma. The patient developed respiratory distress and atelectasis which were treated with biphasic cuirass ventilation. This case suggests that Swyer-James syndrome should be a concern in patients with chronic cough and wheezing, and highlights the importance of taking a careful history and appropriate radiological investigations for diagnosis. Once Swyer-James syndrome is diagnosed, prophylaxis and appropriate management of respiratory infections becomes important.

Assessment of the solid-state gamma camera to depict axillary sentinel lymph nodes in breast cancer patients.

PURPOSE: The solid-state gamma camera is now commercially available offering the advantages of a compact and portable system, currently used mainly in the cardiac region. We evaluate the ability of the solid-state gamma camera to depict axillary sentinel lymph nodes (SLNs) in breast cancer patients. MATERIALS AND METHODS: Preoperative SLN lymphoscintigraphy (LSG) was performed in 19 patients with breast cancer using the solid-state gamma camera. Immediately thereafter, we performed a second LSG using a single detector Anger-type gamma camera, and compared the findings from the two cameras. RESULTS: Concordant results were obtained in 12 (63%) patients with both cameras. In 4 (21%) patients, axillary SLNs were correctly identified only with the solid-state gamma camera. In these patients, the distance between the SLN and the radiopharmaceutical injection site was closer than that of patients who had concordant results (p = 0.001). CONCLUSION: We can depict correctly axillary SLNs with the solid-state gamma camera in comparison with the Anger-type gamma camera. This technique would be useful for assessing SLNs in breast cancer patients.

FDG-PET in a case of multiple bone metastases of gastric cancer.

F-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is useful for surveys to detect bone metastasis because of its greater specificity than bone scintigraphy. However, FDG-PET is also known to yield false-positive results in acute fractures and inflammatory lesions, and distinguishing between benign and malignant lesions is difficult, even when semiquantitative methods are used. We report a case of multiple bone metastases of gastric cancer. One of the bone lesions that was positive for FDG uptake was benign, suggesting that FDG-PET can yield false-positive results.

Do short-time SPECT images of bone scintigraphy improve the diagnostic value in the evaluation of solitary lesions in the thoracic spine in patients with extraskeletal malignancies?

OBJECTIVE: Single photon emission computed tomography (SPECT) images provide many details of the anatomical structure. Also about bone scintigraphy, there are many reports of the improvement of diagnosis by SPECT images. Although SPECT is useful, it requires much time. So to perform SPECT for all cases is difficult in the clinical situation. Recently, due to technical improvements in gamma cameras, we can get SPECT images in a short time. We examined diagnosis of solitary hot spots of thoracic spine in cancer patients using short-time SPECT. And we considered whether short-time SPECT contributes to the precise diagnosis of the lesion. MATERIAL AND METHODS: We performed bone scintigraphy image acquisition and both planar and short-time SPECT of the chest. Short-time SPECT was acquired in 6 minutes. We selected 36 cases with malignancy, whose bone scintigraphy demonstrated a solitary accumulation hot spot in the thoracic spine. Three experienced radiologists in nuclear medicine and 4 beginners diagnosed the images. They interpreted planar, short-time SPECT and maximum intensity projection (MIP) view of the chest of each case. The observers' response data were analyzed with receiver operating characteristic (ROC) curve analysis. RESULTS: Of the three types of images, the Az (the area under ROC curve) values of short-time SPECT were the highest in all the observers except for only one beginner. Compared with experienced observers, beginners scored lower Az values of short-time SPECT. MIP images were constructed using SPECT data, but the Az values of MIP images were not higher than those of planar images. As to diagnosis, beginners tended to interprete most of the accumulations as metastatic lesions. CONCLUSION: Short-time SPECT can be helpful to some degree, but to provide greater benefit, the observers require considerable exercise and experience.

123I-Metaiodobenzylguanidine uptake in the nape of the neck of children: likely visualization of brown adipose tissue.

UNLABELLED: The distribution of radioiodinated metaiodobenzylguanidine (MIBG) has been studied primarily in patients with neuroendocrine tumors-in pediatrics, particularly with neuroblastomas. Sometimes, symmetric accumulation in which no tumor is identified is seen in the nape-of-the-neck region. We estimated visually whether accumulation was found in the nape of the neck and studied the characteristics of the accumulation. METHODS: Retrospectively, we investigated 266 (123)I-MIBG scintigraphic studies performed on pediatric patients who had been treated for neuroendocrine tumors or who were suspected of having such tumors. RESULTS: Accumulation in the nape of the neck was seen in 32 of 266 studies (12%); in none of these cases was the accumulation identified as a tumor by other imaging modalities or follow-up studies. In the same individuals, the accumulation varied and it was observed more often during winter. CONCLUSION: Symmetric (123)I-MIBG accumulations in the nape-of-the-neck region observed in children are thought to be related to the uptake in brown adipose tissue.

(123)I- or (125)I-metaiodobenzylguanidine visualization of brown adipose tissue.

UNLABELLED: (123)I-Metaiodobenzylguanidine (MIBG) accumulations that do not correspond to any tumor are observed occasionally on the medial aspect of the upper back or shoulder of children. The true nature of such accumulations is unknown, and we hypothesized that they represent interscapular brown adipose tissue (IBAT) visualized by scintigraphy. METHODS: Wistar rats (7 wk old) received MIBG labeled with (123)I or (125)I. Autoradiography was performed, and concentrations of the tracer in the interscapular subcutaneous tissue were identified histopathologically. The effects of 6-hydroxydopamine, reserpine, and beta 3-adrenergic receptor agonist (CL316,243) on the accumulation were investigated to elucidate the mechanism of uptake into BAT. RESULTS: Autoradiography showed well-defined distinct accumulation in the subcutaneous tissue on the upper back, and hematoxylin-eosin and anti-uncoupling protein 1 antibody staining confirmed that it was BAT. The percentage injected dose per gram in BAT was as high as that in the heart and was quite different from the concentration in white adipose tissue. Preadministration of 6-hydroxydopamine or reserpine resulted in lower MIBG concentrations in BAT. Activation of the beta 3-adrenergic receptor accelerated the washout of MIBG in BAT and caused an increase in concentration in white adipose tissue. CONCLUSION: MIBG accumulates in the adrenergic nervous system in BAT, and IBAT is distinguished from the surrounding white adipose tissue. To our knowledge, BAT has not been visualized previously. We showed that MIBG scintigraphy might be suitable for the investigation of BAT and treatment of human obesity.

Relationship between cognitive function and regional cerebral blood flow in Alzheimer's disease.

The Mini-Mental State examination (MMSE) is frequently used to assess the cognitive function of neurological patients. The purpose of this study was to investigate associations between regional cerebral blood flow (rCBF) and MMSE scores in Alzheimer's disease (AD) and localization of cognitive functions. Fifty-nine patients with probable AD (21 males and 38 females; mean age 74 years) and 12 normal volunteers (five males and seven females; mean age 73 years) were studied. CBF was measured by SPECT using the N-isopropyl-p-[(123)I]iodoamphetamine autoradiography method. The CBF images were reconstructed in parallel with the orbitomeatal line and parallel to the long axis of the temporal cortex. Regions of interest were set in the cerebral and cerebellar cortex. Multivariate analysis was performed by the step-wise method, using each section of the MMSE as the dependent variable and the rCBF ratio as the independent variable. The decline in rCBF in the parietal cortex and hippocampus reflected disorientation, and the most significant cortex affecting scores on each section of the MMSE were found to be the anterior temporal cortex for registration, the frontal cortex for attention and calculation, the medial temporal cortex for recall, and the posterior temporal cortex for language.

Pattern of 111In-chloride bone marrow scintigraphy in myelodysplastic syndrome; comparison with clinical characteristics.

111In-chloride bone marrow scintigraphy (bone marrow scintigraphy) was performed in patients with myelodysplastic syndrome (MDS), tracer accumulation was classified into patterns, and the relationship between the accumulation patterns and prognostic factors was investigated to assess the usefulness of bone marrow scintigraphy. The subjects were 14 patients diagnosed with MDS. Accumulation of the bone marrow scintigraphy tracer was classified according to the degree of accumulation in the axial bone marrow and peripheral expansion. International Prognostic Scoring System (IPSS), which are frequently used for prognostic evaluation of MDS, and conversion to leukemia were investigated in prognostic factors. We also investigated the relationship between enlargement of the liver and spleen and the prognostic factors. The accumulation patterns were as follows: pattern I, The normal accumulation pattern (2 cases); pattern II, the expanded accumulation pattern (6 cases); pattern III, low accumulation pattern (5 cases); and pattern IV, heterogeneous accumulation pattern (1 case). The relationships between the two prognostic factors and accumulation patterns were investigated, and the prognosis was found to be significantly poorer in the patients with the low accumulation pattern than the expanded accumulation pattern. Enlargement of the liver and spleen was not significantly correlated with the prognostic factors.

Measurement of cerebral blood flow using graph plot analysis and I-123 iodoamphetamine.

PURPOSE: N-isopropyl-p[I-123]iodoamphetamin (IMP) is transiently taken up by the lungs after intravenous injection and its concentration in arterial blood varies depending on the degree of I-123 IMP uptake and subsequent washout. A method that does not require arterial blood sampling would be valuable to measure cerebral blood flow (CBF) using I-123 IMP. METHODS: The authors developed a new theory and a convenient new method of CBF determination using I-123 IMP that does not require blood sampling. Dynamic images of the head and chest were acquired immediately after intravenous injection of I-123 IMP in a series of 42 consecutive patients with cerebrovascular disorders or other brain diseases (31 men, 11 women; mean age, 58 +/- 11 years). Changes in the I-123 IMP counts of the regions of interest set in the head and pulmonary trunk were analyzed by the graph plot method, and the F values (CBF index slope) determined were compared with the mean CBF levels obtained by simultaneous autoradiography. RESULT: The F values correlated well with the mean CBF obtained by autoradiography (r = 0.818, P < 0.001). CONCLUSIONS: This innovative I-123 IMP graph plot analysis method using the time-activity curve of the head and pulmonary trunk alone is a noninvasive, convenient way to measure CBF. It is expected to become the most useful clinical technique for measuring CBF with I-123 IMP. This method can be used for patient follow-up and for comparing different patient groups evaluated in regional CBF studies.

Transient aphasia as late-onset seizure after embolization for dural arteriovenous malformation.

Tc-99m HMPAO single photon emission computed tomography was performed in a patient who had experienced aphasia for 3 days. The patient had a medical history of subarachnoid hemorrhage and intracranial hemorrhage. Both of these hemorrhages were related to a dural arteriovenous malformation that was embolized after the onset of the cerebral vascular events. Focal hyperperfusion was seen in the left temporal lobe adjacent to a perfusion defect corresponding to the old cerebral hemorrhage. The finding was interpreted as the focus of the patient's epilepsy. His aphasia resolved after the administration of anticonvulsant medication for several days.

Intense F-18 FDG accumulation in idiopathic tumoral calcinosis.

An elderly Japanese woman presented to our hospital with a 5-month history of a growing mass on her right cheek. She did not complain of local pain, headache, hearing difficulty, or tinnitus. CT and MRI showed a dense calcified mass and F-18 fluorodeoxyglucose (FDG) PET demonstrated intense accumulation in the mass. Resection of the mass was performed and it was histologically diagnosed as idiopathic tumoral calcinosis.

Cognitive impairment and cerebral hypoperfusion in a CADASIL patient improved during administration of lomerizine.

A 64-year-old woman was admitted to our hospital for recurrent stroke and cognitive impairment and was diagnosed with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Iodine-123 iodoamphetamine single photon emission computed tomography showed hypoperfusion in the whole brain, but cerebral blood flow increased dramatically after the administration of acetazolamide in the cerebral cortex. Lomerizine, a diphenylmethylpiperazine Ca2+ channel blocker, can selectively increase cerebral blood flow. Cognitive decline and cerebral hypoperfusion improved during 2-year administration of lomerizine in this CADASIL patient, and thus, lomerizine is a potential candidate for treating cognitive impairment in CADASIL patients.

Effect of vascular stenosis on perfusion-weighted imaging; differences between calculation algorithms.

PURPOSE: To determine the most suitable postprocessing technique for magnetic resonance (MR) perfusion imaging in patients with vascular stenosis, by comparing the cerebral blood flow (CBF) maps of single photon emission tomography (SPECT) and perfusion MR imaging (MRI). MATERIALS AND METHODS: In 15 consecutive patients (14 men and one woman, mean age 73.9 +/- 6.0 years) with stenosis of common carotid artery (CCA) or internal carotid artery (ICA) of more than 75%, both brain perfusion MRI and brain perfusion SPECT were performed. From perfusion MR images, CBF maps were calculated with the first moment, singular value decomposition (SVD), and block circulant SVD (b-SVD) methods, and CBF maps from each algorithm were compared with those from SPECT. RESULTS: The b-SVD method had the best correlation with SPECT (R = 0.814), followed by the first moment method (R = 0.776) and the SVD method (R = 0.723). The b-SVD method has the least mean difference with SPECT (0.118), the first moment method also had less difference (0.121), and the SVD had greatest mean difference (0.164). CONCLUSION: Our results suggest that in patients with vascular impairment the b-SVD method will be the technique of choice rather than SVD or first moment method.