Comparison of Chemical Exchange Saturation Transfer Imaging with Diffusion-weighted Imaging and Magnetic Resonance Spectroscopy in a Rat Model of Hypoxic-ischemic Encephalopathy

Purpose:

This study aimed to evaluate the effect of chemical exchange saturation transfer (CEST) on the ischemic regions in hypoxic-ischemic encephalopathy (HIE) in comparison with diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) using a 7T-MRI.

Methods:

We used neonatal rats (n = 8), aged 8 days, to clarify the progression of HIE. The rat model of HIE was developed by ligating and severing the left common carotid artery, followed by 45 minutes of recovery, and 60 minutes of hypoxia (8% O₂/92% N₂; 34°C). At 0–2 and 24 hours after the onset of HIE, CEST imaging, DWI, and MRS were performed with a 7T-MRI. The magnetization transfer ratio (MTR) asymmetry curves and four MTR asymmetry maps at 0.5, 1.0, 2.0, and 3.5 ppm were calculated using the CEST images. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were calculated by DWI, and brain metabolites were assessed by MRS.

Results:

In the ischemic regions of neonatal rats, FA was significantly increased at 0–2 hours and decreased at 24 hours after the onset of HIE. ADC in the ipsilateral side was significantly lower than that of contralateral side. All rats with HIE showed hypointense areas on MTR asymmetry maps (2.0 and 3.5 ppm), that did not correspond with the hyperintense areas on DWI. In addition, a significant increase in lactate levels was observed at 0–2 and 24 hours after the onset of HIE.

Conclusion:

CEST MTR maps did not correspond with the hyperintense areas on DWI at 0–2 and 24 hours after the onset of HIE. The change of multi offset CEST signal may be primarily related to the brain metabolites and pH alterations, such as that caused by lactate, after the onset of HIE.

The Status of Stress Myocardial Perfusion Imaging Using 99mTc Pharmaceuticals in Japan: Results from a Nationwide Survey

Objective(s):

To appropriately use one-day myocardial perfusion imaging (MPI) with ^99mTc radiopharmaceuticals (i.e. to avoid shine-through artifacts), injection doses need to be optimized and dose ratios between the 1^st and 2^nd scans should be maintained at ≥ 3. However, the current state of practice in Japan is unclear. Thus, the aim of this study was to clarify the details of MPI protocols using ^99mTc radiopharmaceuticals in Japan.

Methods:

A nationwide survey was conducted in June and July 2016. Questionnaires about stress MPI protocols using ^99mTc radiopharmaceuticals were sent to 641 nuclear medicine facilities.

Results:

Responses were received from 246 facilities. One-day protocols were used in 97.1% of the facilities. The most common injection dose ratio was 2.5. Only 18.2% of facilities achieved the recommended injection dose ratio. Stress-only protocols were performed in only 1.7% of facilities; the primary reasons for not performing stress-only protocols were as follows: 1) “The reading-physician cannot interpret the image just after the first scan,” and 2) “Preparation of radiopharmaceuticals and scan arrangements turn out to be complicated.”

Conclusion:

Approximately 80% of nuclear medicine facilities do not follow the recommended injection dose ratio. Stress-only protocols are ideal, but are performed at very few facilities. Both optimization and standardization of stress MPI protocols using ^99mTc radiopharmaceuticals are needed in Japan.

Current status of stress myocardial perfusion imaging pharmaceuticals and radiation exposure in Japan: Results from a nationwide survey

BACKGROUND

Ionizing radiation generated during medical imaging procedures is a matter of concern. However, the current status of radiopharmaceutical use in stress myocardial perfusion imaging (MPI) and the radiation exposure from these radiopharmaceuticals is unknown in Japan.

METHODS AND RESULTS

A nationwide survey was conducted from June through July 2016. The questionnaires on the radiopharmaceuticals used and their administered doses during stress MPI were sent to 641 nuclear medicine facilities. The responses were collected from 431 facilities and the effective dose (ED) for an adult with standard body weight was calculated. Forty-three percent of the facilities used only 201TlCl, 35% used only 99mTc radiopharmaceuticals, and the remaining 22% used both. The two main reasons for using 201TlCl instead of 99mTc radiopharmaceuticals were "more familiarity with the usage of 201TlCl than 99mTc radiopharmaceuticals" and "apprehension about increasing the burden of physicians performing tracer injection twice." The mean ED was 14.0 ± 5.5 mSv (range, 3.9 to 25.2 mSv), which was higher than that reported in other countries.

CONCLUSIONS

The ED of stress MPI radiopharmaceuticals in Japan is probably higher than the world standard because more than 50% of the facilities still use 201TlCl. We recommend revising the routine stress MPI protocol to reduce the effects of ionizing radiation.

Imaging of the thyroid and parathyroid using a cardiac cadmium zinc telluride camera: Phantom studies

Purpose: Cadmium zinc telluride (CZT) detectors have recently been introduced to the field of clinical nuclear cardiology. However, the feasibility of using them for organs other than the heart remains unclear. The aim of this study was to evaluate the potential of a cardiac CZT camera to acquire thyroid and parathyroid images. We used custom-made phantoms and the currently available standard protocols for CZT, instead of a sodium-iodine scintillation (NaI) camera. Materials and Methods: Thyroid phantoms with or without parathyroid adenomas were made from agar using radiopharmaceuticals (99mTc or 123I) and imaged using CZT and NaI cameras. Using the CZT camera data, we prepared maximum intensity projection (MIP) images and planar equivalent (PE) images. Image counts were compared to those from the NaI camera, and the radioactivity of the phantoms was measured. For parathyroid imaging, three different protocols with the NaI camera were tested using MIP images. Results: For thyroid imaging, MIP could provide images as clear as those obtained from the NaI camera. The radioactivity and image counts correlated better for the PE images than the MIP images, especially for 123I images. We succeeded in obtaining clear parathyroid adenoma images from MIP images using all three protocols. Conclusion: A cardiac CZT camera can effectively perform qualitative and quantitative assessments of the thyroid and parathyroid organs.

Differences in accumulation and the transport mechanism of l- and d-methionine in high- and low-grade human glioma cells

INTRODUCTION

Although [S-methyl-11C]-labeled L-methionine and D-methionine (¹¹C-L-MET and ¹¹C-D-MET) are useful radiotracers for positron emission tomography imaging of brain tumors, it is not known whether the accumulation and transport mechanisms underlying uptake of ¹¹C-D-MET and ¹¹C-L-MET are the same. ¹¹C-L-MET is mainly taken up by the amino acid transport system L. We evaluated accumulation and the transport mechanism of D-MET in high- and low-grade human glioma cells in vitro.

METHODS

The expression of transport system genes in high- (A172 and T98G) and low-grade (SW1088 and Hs683) glioma cells was quantitatively analyzed. Accumulation of [S-methyl-³H]-L-MET (³H-L-MET) and [S-methyl-³H]-D-MET (³H-D-MET) in these cells was compared during 60min of incubation. The transport mechanism of ³H-L-MET and ³H-D-MET was investigated by incubating the cells with these compounds and examining the effect of the inhibitors 2-amino-2-norbornane-carboxylic acid or α-(methylamino) isobutyric acid.

RESULTS

Absolute expression levels of system L and system alanine-serine-cysteine (ASC) in high-grade glioma cells were higher than in low-grade cells. In high-grade glioma cells, expression of system ASC genes was higher than that of system L genes. ³H-D-MET, which is transported by systems L and ASC, accumulated at higher levels than ³H-L-MET at all incubation times because ³H-D-MET is more sensitive to system ASC than ³H-L-MET. Conversely, in low-grade glioma cells with lower expression of system L and ASC, ³H-D-MET accumulated at higher levels than ³H-L-MET in early incubation times because ³H-D-MET may be more sensitive to system ASC than system L.

CONCLUSION

³H-D-MET was mainly transported by systems L and ASC and sensitive to system ASC, whereas ³H-L-MET was transported by system L in human glioma cells. In vitro, the accumulation of ³H-D-MET was significantly higher than that of ³H-L-MET during the entire incubation time in high-grade glioma cells, and in early incubation times in low-grade glioma cells.

Unusually increased metaiodobenzylguanidine uptake in a gastrointestinal stromal tumor of the stomach

A 70-year-old woman with a submucosal gastric tumor was referred to our hospital for surgical treatment. Upon examination, it was found that she had hypertension, and abdominal computed tomography revealed swelling on both adrenal glands. The patient was examined with gamma camera imaging and iodine-123 metaiodobenzylguanidine (MIBG), because her hypertension was thought to be due to a suspected adrenomedullary tumor. The planar image showed an unexpected abnormal uptake of MIBG in the upper abdomen. On single-photon emission computed tomographic images, the area of abnormal tracer uptake was thought to correspond to the known gastric tumor. The surgical procedure and histological assessments revealed that the gastric tumor was a gastrointestinal stromal tumor (GIST). MIBG can accumulate in GISTs as well as in neuroendocrine tumors of the medulla of the adrenal glands. Although the cause of radiolabeled MIBG uptake in GISTs is uncertain, further studies are necessary to establish the significance of MIBG scintigraphy in GIST imaging.

APP transgenic mice for modelling behavioural and psychological symptoms of dementia (BPSD)

The discovery of gene mutations responsible for autosomal dominant Alzheimer's disease has enabled researchers to reproduce in transgenic mice several hallmarks of this disorder, notably Aβ accumulation, though in most cases without neurofibrillary tangles. Mice expressing mutated and wild-type APP as well as C-terminal fragments of APP exhibit variations in exploratory activity reminiscent of behavioural and psychological symptoms of Alzheimer dementia (BPSD). In particular, open-field, spontaneous alternation, and elevated plus-maze tasks as well as aggression are modified in several APP transgenic mice relative to non-transgenic controls. However, depending on the precise murine models, changes in open-field and elevated plus-maze exploration occur in either direction, either increased or decreased relative to controls. It remains to be determined which neurotransmitter changes are responsible for this variability, in particular with respect to GABA, 5HT, and dopamine.

[Granular cell tumor in the mediastinum; report of a case]

Granular cell tumor is found in various organs but is rare in the mediastinum. We report a case of 21-year-old woman with a granular cell tumor in the left upper mediastinum. Chest computed tomography (CT) showed a 30 x 20 mm well circumscribed tumor in the left upper mediastinum. Tumor resection was performed. It was found that the tumor involved the sympathetic nerve. Histopathologically, the tumor consisted of cells with eosinophilic granules and diagnosed as a granular cell tumor.

Accumulation of spermidine/spermine N1‐acetyltransferase and alternatively spliced mRNAs as a delayed response of HeLa S3 cells following X‐ray irradiation

PURPOSE

A key enzyme of polyamine catabolism, spermidine/spermine N(1)-acetyltransferase (SSAT), is responsive to antiproliferative agents. The role of SSAT in cellular responses to X-ray irradiation was examined.

MATERIALS AND METHODS

Exponentially growing HeLa S3 cells were irradiated by X-rays, and mRNA levels for SSAT were measured as a function of post-irradiation time through Northern hybridization. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect alternatively spliced SSAT mRNAs. The intracellular polyamine content was measured by the o-phthalaldehyde method and the enzymatic activity of SSAT by the increased amount of acetylated spermidine after incubation.

RESULTS

Not only SSAT mRNA, but also an alternatively spliced mRNA accumulated at the initial stage of growth inhibition after the first or second replication of irradiated cells. The maximum fold increase relative to the level of non-irradiated cells was 3.0-3.5 for both transcripts after 5-Gy irradiation. On the other hand, the mRNA of ornithine decarboxylase, a key enzyme of polyamine synthesis, was little influenced by X-ray treatment. Enzymatic activity of SSAT and the acetylspermidine level were elevated after X-ray irradiation.

CONCLUSIONS

Activation of SSAT and the induction of alternatively spliced mRNA of the SSAT gene play an important role in regulating growth inhibition and cell death after X-ray irradiation.

Myocardial scintigraphy after pacemaker implantation for congenital complete atrioventricular block

Patients with isolated congenital complete atrioventricular block (CCAVB) occasionally develop dilated cardiomyopathy (DCM), despite early pacemaker implantation. However, the etiology of the DCM and its relationship to permanent ventricular pacing are not fully understood. Twenty-five patients with CCAVB underwent (99m) technetium (Tc) myocardial perfusion scintigraphy. Five patients were studied before and after pacing, providing a total of 30 image sets, which were divided into three groups; group 1: CCAVB before pacemaker implantation (PMI) (n = 11); group 2: CCAVB after PMI who did not subsequently develop DCM (n = 13); group 3: CCAVB after PMI who subsequently developed DCM (n = 6). Perfusion defects on single-photon-emission computed tomography (SPECT) were identified in group 1, 0 of 11 patients; group 2, 85% of patients; and group 3, 100% of patients. In groups 2 and 3, in patients with right ventricular pacing, the perfusion defects were mainly in the septum or between the apex and septum. On 20 segments' polar maps, the distribution of %uptake showed a similar pattern in groups 2 and 3, the degree of decreased %uptake and the number of segments with decreased %uptake being more severe in group 3. "Artificial" left bundle branch block (LBBB) pattern myocardial contraction induced by right ventricular pacing decreased myocardial perfusion around the apex and septum. Some patients with CCAVB will develop left ventricular dysfunction caused by artificial LBBB-induced interventricular asynchrony.

Masked Prosthetic Graft to Sigmoid Colon Fistula Diagnosed by 18-fluorodeoxyglucose Positron Emission Tomography

The diagnosis of low grade prosthetic graft infection or aorto-enteric fistula is difficult using conventional radiographic imaging modalities. We report a case of aorto-enteric fistula to the sigmoid colon diagnosed by the new technique of 18-fluorodeoxyglucose positron emission tomography.

Benign variations and incidental abnormalities of myocardial FDG uptake in the fasting state as encountered during routine oncology positron emission tomography studies

Increased 18fluoro-2-deoxyglucose (FDG) uptake in the myocardium is frequently observed while performing clinical positron emission tomography (PET) body scans for oncology under fasting conditions. This article reviews the normal variations and abnormal appearances of myocardial FDG accumulation which are likely to be encountered in the routine PET studies. Knowledge about the myocardial glucose metabolism and specific abnormalities are indispensable in the interpretation of myocardial FDG uptake.

A case of malignant pheochromocytoma with early intense uptake and immediate rapid washout of 99mTc-tetrofosmin characterizing the overexpression of anti-apoptotic Bcl-2

Defective apoptotic program due to the overexpression of the anti-apoptotic Bcl-2 protein of the outer mitochondrial membrane may be a cause of the poor response of malignant pheochromocytoma to 131I-MIBG therapy. We report a case of malignant pheochromocytoma which showed early intense uptake and immediate rapid washout of 99mTc-tetrofosmin characterizing the overexpression of anti-apoptotic Bcl-2 and which was refractory to 131I-MIBG therapy.

Renal Function in Patients with Abdominal Aortic Aneurysm

AIMS

Renal dysfunction occurs occasionally after the repair of abdominal aortic aneurysm (AAA), and preoperative renal function is considered as one of the potential causes. The present study was designed to evaluate and compare renal function and risk factors of AAA patients with those of hypertensive patients.

METHODS

We prospectively examined 95 patients with AAA and 72 patients with essential hypertension (HT) without other cardiovascular diseases (CVD). Renal function, urinary albumin excretion (UAE) and renal scintigraphy were compared. Kidney size was calculated using ultrasonography.

RESULTS

Serum creatinine and creatinine clearance in AAA patients was worse than in HT patients. Smoking status was more apparent in AAA patients. Renal artery stenosis occurred in 8 patients with AAA. Renal scintigraphy showed normal function in 19%, hypofunction in 69% and severe dysfunction in 12% of the AAA patients, and normal function in 42% and hypofunction in 58% of the HT patients (p < 0.0001). Multivariate linear regression analysis showed that renal function was related to age, UAE, CVD, smoking status and kidney size for all patients, UAE, CVD, smoking status and kidney size for AAA patients, and age and kidney size for HT patients.

CONCLUSION

Renal function of AAA patients was worse than HT patients without other CVD. The risk factors for renal dysfunction were different between AAA and HT patients. These preoperative conditions may relate to the postoperative renal dysfunction seen in AAA patients.

Glucose utilization in the inferior cerebellar vermis and ocular myoclonus

In a patient with symptomatic ocular myoclonus, the authors observed the regional cerebral metabolic rate of glucose use (rCMRGlu) before and after successful treatment with clonazepam. Even after the symptoms resolved, the rCMRGlu in the hypertrophic olive increased persistently, whereas that in the inferior cerebellar vermis contralateral to the hypertrophic olive decreased. The inferior cerebellar vermis, belonging to the vestibulocerebellar system, may be associated with the generation of symptomatic ocular myoclonus.

Microalbuminuria and deterioration of renal function after elective repair of infrarenal abdominal aortic aneurysm

AIMS

Renal dysfunction affects the prognosis of patients after aortic surgery. However, the factors associated with the postoperative deterioration of renal function has not been clarified precisely.

METHOD

We prospectively examined renal function in 80 patients (age: 73 +/- 7 years, 66 males) who required the elective repair of infrarenal abdominal aortic aneurysm (AAA). Serum creatinine (Scr) was measured. 24-h-creatinine clearance (Ccr) and urinary albumin excretion (UAE) were determined. Renal volume and mean renal length were calculated using the data obtained by ultrasonography. 48 patients showed normal UAE (< 30 mg/day), and 24 had microalbuminuria (30-300 mg/day) and 8 had overt proteinuria (> 300 mg/day). Scr were 0.9 +/- 0.4, 1.0 +/- 0.3 and 2.1 +/- 1.3 mg/dl, respectively.

RESULTS

On Day 5 after surgery, 12 patients (15%) showed deterioration of renal function as defined either by an increase in Scr (> or = 0.5 mg/dl) or by a decrease in Ccr > or =20%). The acute deterioration of renal function was related to mean renal volume, mean renal length, duration of operation and the use of antibiotics. At Month 12 after surgery, Scr increased in the overt proteinuria group. The deterioration of renal function at Month 12 was found in 8 patients (10%) with microalbuminuria or overt proteinuria, and related to preoperative Ccr, UAE, mean renal volume, mean renal length, smoking status and blood pressure.

CONCLUSION

We conclude that the deterioration of renal function occurred in considerable number of patients with AAA after elective operation on acute and chronic phase, although the development of end-stage renal failure is rare. Factors related to the acute and late deterioration appears to be different. UAE and renal size should be measured, even if Scr is in normal range at preoperative observation.

Regional acetylcholinesterase activity and its correlation with behavioral performances in 15-month old transgenic mice expressing the human C99 fragment of APP

In addition to Abeta plaques and neurofibrillary tangles, Alzheimer's disease (AD) is characterized by increased brain levels of APP C-terminal fragments. In the present investigation, the cholinergic innervation in forebrain regions of transgenic mice (Tg13592) expressing the human betaAPP C99 fragment was compared to that of non-transgenic controls by measuring the activity of the non-specific catabolic enzyme, acetylcholinesterase (AChE). The AchE activity of Tg13592 mice was altered in several regions implicated in the functional loop of regulation between septum and hippocampus, vulnerable in Alzheimer pathology and critically involved in cognitive functions. In particular, AChE activity was upregulated in three basal forebrain regions containing cholinergic cell bodies, prelimbic cortex, anterior subiculum, and paraventricular thalamus, but downregulated in lateral septum and reticular thalamus. The increased activity in medial septum and anterior subiculum was linearly correlated with poor performances in a spatial learning task, possibly due to cell stress mechanisms. Because of some similarities in terms of neurochemistry and behavior, this mouse model may be of use for studying prodromal AD.

Exploratory activity and spatial learning in 12-month-old APP695SWE/co+PS1/ΔE9 mice with amyloid plaques

APP(695)SWE/co+PS1/DeltaE9 mice with Abeta plaques in neocortex and hippocampus were evaluated in tests of exploratory activity and spatial learning. On the initial testing day, 12-month-old APP(695)SWE/co+PS1/DeltaE9 mice spent more time than non-transgenic controls in the open arms of the elevated plus-maze. The bigenic group also travelled farther in the central region of the open-field without spending more time there. Only the bigenic group alternated above chance in the T-maze. In the Morris water maze, APP(695)SWE/co+PS1/DeltaE9 mice were impaired during acquisition of the hidden platform sub-task and the probe trial but not in the visible platform test. These results indicate a selective spatial deficit and disinhibitory tendencies in a mouse model with amyloid pathology.

Detection of aortic graft infection by fluorodeoxyglucose positron emission tomography: Comparison with computed tomographic findings

OBJECTIVE

Radionuclide imaging with fluorodeoxyglucose (FDG) and positron emission tomography (PET) has been proposed for the identification of vascular graft infection; however, its accuracy has not been determined. We performed this prospective study to compare the usefulness of FDG-PET in the assessment of vascular graft infection relative to computed tomography (CT).

METHODS

FDG-PET was performed for 33 consecutive patients with a suspected arterial prosthetic graft infection. The PET images were then assessed visually in terms of the density of uptake. In cases with positive uptake, the pattern of accumulation was also defined, such as focal or diffuse uptake. We compared the diagnostic efficiency of PET with contemporaneous CT in detection of infection of the arterial prosthetic graft.

RESULTS

On the basis of the surgical, microbiological, and clinical follow-up findings, the aortic grafts were considered infected in 11 patients and not infected in 22 patients. Although the sensitivity of PET (91%) was higher than that of CT (64%), its specificity (64%) was lower than that of CT (86%). When focal uptake was set as the positive criterion in FDG, the specificity and positive predictive value of PET for the diagnosis of aortic graft infection improved significantly to 95% (P < .05 for both).

CONCLUSIONS

Although both techniques are useful in evaluation of patients with suspected aortic graft infection, using the characteristic FDG uptake pattern described previously as a diagnostic criterion made the efficacy of FDG superior to that of CT in the diagnostic assessment of patients with suspected aortic graft infection.

Radionuclide imaging metabolic activity of brown adipose tissue in a patient with pheochromocytoma

We describe a patient with extra-adrenal pheochromocytoma and high plasma norepinephrine levels. Radionuclide images of this patient obtained using (18)F-fluorodeoxyglucose and (123)I-metaiodobenzylguanidine revealed bilateral tracer accumulation in the shoulder and lower neck. The regions of radiotracer uptake corresponded to the location of human brown adipose tissue (BAT). Excessive sympathetic stimulation by high circulating catecholamine concentrations augmented the metabolic activity and tracer uptake in the BAT. This study showed that radionuclide imaging can noninvasively visualize human BAT in terms of metabolic and functional activity.

Evaluation of the use of a standard input function for compartment analysis of [123I]iomazenil data: factors influencing the quantitative results

Adoption of standard input function (SIF) has been proposed for kinetic analysis of receptor binding potential (BP), instead of invasive frequent arterial samplings. The purpose of this study was to assess the SIF method in quantitative analysis of [123I]iomazenil (IMZ), a central benzodiazepine antagonist, for SPECT. SPECT studies were performed on 10 patients with cerebrovascular disease or Alzheimer disease. Intermittent dynamic SPECT scans were performed from 0 to 201 min after IMZ-injection. BPs calculated from SIFs obtained from normal volunteers (BPs) were compared with those of individual arterial samplings (BPo). Good correlations were shown between BP(o)s and BP(s)s in the 9 subjects, but maximum BP(s)s were four times larger than the corresponding BP(o)s in one case. There were no abnormal laboratory data in this patient, but the relative arterial input count in the late period was higher than the SIF. Simulation studies with modified input functions revealed that height in the late period can produce significant errors in estimated BPs. These results suggested that the simplified method with one-point arterial sampling and SIF can not be applied clinically. One additional arterial sampling in the late period may be useful.

Cardiac Tumor as an Initial Manifestation of Acquired Immunodeficiency Syndrome

A cardiac tumor was the first manifestation of acquired immunodeficiency syndrome (AIDS) in a female patient in a state of severe immunodeficiency caused by human immunodeficiency virus (HIV) infection. The extensive cardiac and extracardiac involvement shown by various imaging modalities, including echocardiography and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), suggested that she was in the critical stage of non-Hodgkin's lymphoma (NHL). AIDS was treated by highly active-antiretroviral therapy and the NHL was treated by a combination of rituximab-cyclophosphamide-vincristine-doxorubicine-predonisolone. After 6 cycles of chemotherapy, she was in complete remission. Her cardiac tumor dramatically reduced in size and FDG-PET showed no positive uptake on whole body imaging. Generally, an AIDS-related cardiac tumor tends to be diagnosed at the late stage of the disease because of its nonspecific clinical findings, resulting in an extremely poor prognosis. In the present case, the cardiac tumor was detected by echocardiography and treated with appropriate chemotherapy. Early diagnosis and prompt treatment may improve a patient's prognosis.

Transgenic mice expressing the human C99 terminal fragment of betaAPP: effects on cytochrome oxidase activity in skeletal muscle and brain

In order to furnish a combined model of relevance to human inclusion-body myopathy and Alzheimer's disease, transgenic mice expressing human betaAPP-C99 in skeletal muscle and brain under the control of the cytomegalovirus/beta-actin promoter were produced (Tg13592). These transgenic mice develop Abeta deposits in muscles but not in brain. Cell metabolic activity was analyzed in brain regions and muscle by cytochrome oxidase (CO) histochemistry, the terminal enzyme of the electron transport chain. By comparison to age-matched controls of the C57BL/6 strain, CO activity was selectively increased in dark skeletal muscle fibers of Tg13592 mice. In addition, only increases in CO activity were obtained in those brain regions where a significant difference appeared. The CO activity of Tg13592 mice was elevated in several thalamic nuclei, including laterodorsal, ventromedial, and midline as well as submedial, intralaminar, and reticular. In contrast, the groups did not differ in most cortical regions, except for prefrontal, secondary motor, and auditory cortices, and in most brainstem regions, except for cerebellar (fastigial and interpositus) nuclei and related areas (red and lateral vestibular nuclei). No variation in cell density and surface area appeared in conjunction with these enzymatic alterations. The overproduction of betaAPP-C99 fragments in brain without (amyloidosis did not appear to affect the metabolic activity of structures particularly vulnerable in Alzheimer's disease.

Exploratory activity, anxiety, and motor coordination in bigenic APPswe + PS1/ΔE9 mice

Bigenic APPswe + PS1/DeltaE9 mice with Abeta plaque formation in neocortex and hippocampus were evaluated in three tests measuring exploratory activity. By comparison to a non-transgenic group controlled for age and gender, 7-month-old APPswe + PS1/DeltaE9 mice spent more time in the open arms and had higher open/total entries and duration in the elevated plus-maze, indicative of disinhibitory tendencies. On the contrary, the groups did not differ in T-maze and open-field tests. Moreover, the motor coordination of the bigenic group was equivalent to that of controls in stationary beam, coat-hanger, rotorod, and grip strength tests. No mouse displayed neurological signs, such as pathological reflexes, myoclonus, or convulsions. The results in the elevated plus-maze test are akin to the loss of inhibitory control observed in some patients with Alzheimer's disease.

Superimposed display of coronary artery on gated myocardial perfusion scintigraphy

Fusion of images of vascular anatomy and of myocardial perfusion images might be helpful for understanding the relationship between ischemia and the responsible vessels. The aim of this study was to develop a simple means of superimposing the images obtained from coronary angiography and gated myocardial perfusion SPECT.

METHODS

Right and left oblique views from conventional coronary angiography and left ventriculography (LVG) were stored as 512 x 512 x 8-bit digital datasets and combined. We reconstructed images from routine gated myocardial perfusion imaging (MPI) by using (99m)Tc-tetrofosmin to match the oblique positions between the image from MPI and combined angiographic images. We then generated a 3-dimensional (3D) surface map by using the quantitative gated SPECT (QGS)/quantitative perfusion SPECT (QPS) program. Both the combined angiographic images and the 3D surface map were rescaled and unified by registering the internal landmarks between the 2 images. After subtraction of the LVG image, the coronary angiogram and the 3D surface map were fused into 1 image. All processes were performed with the QGS/QPS program and commercially available graphic software. We applied this method to datasets from a cardiac phantom and from several patients with coronary artery disease.

RESULTS

In the phantom study, our technique could obtain a 3D surface map in which the oblique angle was identified as that of radiography and could realize image registration and superimposition of radiography on scintigraphy. The preliminary results from the patients indicated that the markedly stenotic vessels showed good coincidence with the regional myocardial perfusion abnormalities on the unified images. In addition, these images could show the relationship between the coronary artery and regional wall motion in the gated mode.

CONCLUSION

We developed a simple method of superimposing the image of the coronary artery tree on images from gated MPI. The technique yielded useful information about myocardial perfusion and function as well as the supplying coronary artery.

Transgenic mice overexpressing both amyloid beta-protein and perlecan in pancreatic acinar cells

Heparan sulfate proteoglycans such as perlecan are thought to facilitate amyloid fibril formation. Tg3695 mice overexpress perlecan core protein in many tissues including the brain and pancreas. Tg13592 mice overexpress the signal plus 99-amino acid carboxyl terminal sequences (C99) of amyloid beta-protein precursor in multiple tissues and develop amyloid deposits in the pancreas. To investigate a role of perlecan in beta-amyloidosis, we established doubly transgenic mice by crossing the two lines of transgenic mice. The expression levels of the two transgenes remained unchanged in the brain and pancreas and the doubly transgenic mice did not develop amyloid deposits in the brain up to 19-months of age. Amyloid load detected by thioflavine S in the pancreas of the doubly transgenic mice was not significantly different from that in the transgenic littermates expressing only C99. Amyloid load in the pancreas increased during aging. We found a positive correlation between the Abeta-immunoreactive (non-fibrillar and fibrillar) and thioflavine S-positive (fibrillar) Abeta deposits in the single (C99) but not doubly transgenic mice. Our results suggest that perlecan does not independently influence amyloid formation in the pancreas of the transgenic mice and that there may be other factors that may modulate amyloid formation together with perlecan.

Gated myocardial SPECT to predict response to beta-blocker therapy in patients with idiopathic dilated cardiomyopathy

Because of the difficulty of predicting the response of patients with idiopathic dilated cardiomyopathy (IDC) to beta-blocker therapy, this study was performed to evaluate whether gated myocardial SPECT (gated SPECT) could be useful for predicting that response.

METHODS

We performed gated SPECT with (99m)Tc-sestamibi on 38 patients with IDC before treatment with a beta-blocker and standard medication. Perfusion abnormalities, left ventricular (LV) function, and spheric distortion were assessed by a quantitative software program.

RESULTS

We classified patients into 2 groups according to improvement in LV function after 4 mo of therapy. The groups consisted of 16 poor responders whose LV ejection fraction (LVEF) increased less than 10% and 22 good responders whose LVEF increased by 10% or more. The patient characteristics before therapy, including LV volume and LVEF, did not significantly differ between the 2 groups, but the size of the myocardial perfusion defect and spheric distortion were significantly greater in poor responders than in good responders.

CONCLUSION

Gated SPECT, by allowing simultaneous assessment of perfusion, function and geometry, might be useful for predicting the response of patients with IDC to beta-blocker therapy.

Apoptosis in human oral squamous cell carcinomas is induced by 15-deoxy-delta 12,14-prostaglandin J2 but not by troglitazone

15-deoxy-Delta(12,14)-prostaglandin J(2) (15-d-PGJ(2)) and troglitazone have been shown to induce apoptosis in several carcinoma cell lines. However, apoptotic signaling pathways of these agents are poorly understood. We tested the hypothesis that peroxisome proliferator-activated receptor-gamma ligands such as these two agents will induce caspase-mediated apoptosis in human oral squamous cell carcinomas (SCC). Treatment of these cell lines with 15-d-PGJ(2) or troglitazone decreased cell viability in a time- and dose-dependent manner. 15-d-PGJ(2), but not troglitazone, induced apoptosis, and this effect was time-dependent. Exposure of cells to 20 micro M of 15-d-PGJ(2) initiated early cytochrome c release, followed by late caspase activation. Furthermore, co-treatment with caspase inhibitors such as Z-VAD-FMK or Z-DEVD-FMK of oral SCC cells that had been treated with 20 micro M of 15-d-PGJ(2) blocked apoptosis. Our study demonstrates that treatment with 15-d-PGJ(2), but not troglitazone, induces apoptosis in human SCC cell lines, and 15-d-PGJ(2) appears to work through cytochrome c release and caspase activation.

Visualization of interscapular brown adipose tissue using (99m)Tc-tetrofosmin in pediatric patients

Brown adipose tissue (BAT) is a site of nonshivering thermogenesis in mammals. The mitochondria of BAT operate in an uncoupled mode and increase fatty acid oxidation to produce heat at birth. Thus, the BAT of human infants and children contains more active mitochondria than that of adults. We surmised that because (99m)Tc-tetrofosmin can be absorbed by functional mitochondria in the myocardium and in tumor cells, it could reveal mitochondrial function in BAT.

METHODS

Between January 1999 and December 2002, we retrospectively analyzed 385 consecutive studies of (99m)Tc-tetrofosmin uptake in pediatric patients with cardiac disorders. All patients with symmetric (99m)Tc-tetrofosmin accumulation within the neck and shoulder region according to planar images were selected, and the features of the uptake were analyzed.

RESULTS

Increased symmetric (99m)Tc-tetrofosmin uptake in the interscapular BAT was a typical profile of 65 of the 385 patients (17%). The frequency of (99m)Tc-tetrofosmin uptake was significantly higher in winter than in spring or summer (P < 0.05) and prominent in newborns. The frequency peaked between 0 and 2 y of age and then declined with age.

CONCLUSION

Gamma-camera imaging with (99m)Tc-tetrofosmin can reveal interscapular BAT distribution in infants and children in terms of mitochondrial activity.

Efficacy of screening for primary aldosteronism by adrenocortical scintigraphy without discontinuing antihypertensive medication

BACKGROUND

Recently, it has been proposed that discontinuation of antihypertensive medications is not necessarily essential for the measurement of plasma aldosterone-to-renin ratios. We examined the efficacy of adrenocortical scintigraphy performed without modification of antihypertensive medications.

METHODS

A retrospective study was conducted on 119 patients, in whom functional tests, anatomic studies, and adrenocortical scintigraphy were replete. Interrelationship among these was studied. The patients tested were being treated with antihypertensive medications from several classes including angiotensin-converting enzyme inhibitors, calcium antagonists, beta-blockers, diuretics, and spironolactone.

RESULTS

Significantly higher percentage of scintigraphy positive patients had plasma aldosterone-to-renin ratio of greater than 25:1. Positive rate for adrenal nodules by anatomic studies was significantly higher in the scintigraphy positive patients than in the scintigraphy negative patients. Finally, the percentage of patients who underwent adrenalectomy was higher in the scintigraphy positive patients than in the scintigraphy negative patients.

CONCLUSIONS

We conclude that adrenocortical scintigraphy is a valid evaluation tool for primary aldosteronism and that the discontinuation of antihypertensive medications is not a requirement for this test.

Transgenic mice expressing the betaAPP695SWE mutation: effects on exploratory activity, anxiety, and motor coordination

The functional consequences of the betaAPP transgene with the Swedish mutation in mice were assessed in tests of exploratory activity and motor coordination. The betaAPP(695)SWE (Tg2576) transgenic mice are characterized by Abeta plaque formation in the neocortex and hippocampus. By comparison to non-transgenic mice controlled for age and gender, 17-month-old betaAPP(695)SWE transgenic mice displayed impaired spontaneous alternation, increased activity levels in the peripheral part of the open-field, and reduced anxiety in the elevated plus-maze. These results are similar to the loss of inhibitory control observed in some patients with Alzheimer's disease. These measures may be added to cognitive dysfunctions as testing ground for Abeta vaccination and other attempts at experimental therapies.

Acetazolamide assisted Tc-99m MAG3 renography to assess renal blood flow reserve

OBJECTIVE

The present study examines whether or not baseline and acetazolamide (ACZ) Tc-99m MAG3 renography can assess renal blood flow reserve.

METHODS

Renography proceeded for 50 min after sequential injections of 370 MBq Tc-99m MAG3 for baseline renography and 10 min after a 1,000 mg injection of ACZ for ACZ renography. Effective renal plasma flow of renal cortex (cERPF) in each kidney and the percentage change in cERPF of those parameters (deltaERPF) were obtained before and after the administration of ACZ in 10 subjects without hypertension or diabetes (normal group), in 10 with essential hypertension (hypertensive group) and in 10 who had Type 2 diabetes with hypertension (diabetic group). A placebo test was performed in the 10 without hypertension or diabetes using distilled water instead of ACZ (placebo group).

RESULTS

The placebo test performed in the 10 without hypertension or diabetes using distilled water instead of ACZ indicated that the parameter variance between the two types of renogram was below 3.2%. The cERPF of baseline and ACZ Tc-99m MAG3 renography and deltaERPF in the normal, hypertensive and diabetic groups were 89 +/- 10 and 110 +/- 10 ml/min, 89 +/- 14 and 117 +/- 22 ml/min, 100 +/- 23 and 112 +/- 23 ml/min, respectively, and 24.5 +/- 13.5%, 26.0 +/- 9.7% and 12.3 +/- 11.1%, respectively. The difference in the cERPF value was significant in the normal and hypertensive groups whereas this did not change in the diabetic group before or after ACZ administration.

CONCLUSIONS

We suggested that the deltaERPF determined by baseline and ACZ Tc-99m MAG3 renography is a useful parameter for assessing renal blood flow reserve.

Transgenic mice expressing the human C99 terminal fragment of betaAPP: effects on spatial learning, exploration, anxiety, and motor coordination

The functional consequence of beta-amyloid precursor protein (betaAPP) manipulation on behavior was assessed in Tg13592 mice, characterized by transgene expression of the 99 amino acid C-terminal sequence of human betaAPP in brain and skeletal muscle but with plaque formation only in muscle. By comparison to the C57BL/6 background strain controlled for age and gender, Tg13592 transgenic mice had fewer movements in an automated chamber and fewer enclosed arm entries in the elevated plus-maze. This hypoactivity was probably due to a loss in the motivation to explore novel environmental stimuli rather than motor weakness or anxiety. In addition, the acquisition of place learning in the Morris water maze task was impaired in Tg13592 mice. The transgenic mice were not impaired in a probe trial or while swimming toward a visible platform. These results are concordant with the hypothesis that transgene expression of the C-terminal sequence of human betaAPP in brain is sufficient for causing behavioral abnormalities. The hypoactivity and the spatial learning deficit were associated with higher cytochrome oxidase activity seen in thalamic nuclei, indicating that altered regional brain metabolism caused by betaAPP transgene expression may be responsible for the behavioral changes.

Noninvasive measurement of myocardial activity concentrations and perfusion defect sizes in rats with a new small-animal positron emission tomograph

BACKGROUND

We explored the feasibility of measuring regional tracer activity concentrations and flow defects in myocardium of rats with a high spatial resolution small-animal PET system (microPET).

METHODS AND RESULTS

Myocardial images were obtained after intravenous (18)F-fluorodeoxyglucose (18FDG) in 11 normal rats (group 1) and assembled into polar maps. Regional 18F activity concentrations were measured in 9 regions of interest and compared with tissue activity concentrations measured by well counting. In another 9 rats (group 2), myocardial perfusion images were acquired with 13N-ammonia at baseline and during coronary occlusion. On the polar maps recorded during coronary occlusion, the size of perfusion defects was measured as the myocardium with <50% of maximum activity and expressed as percent total myocardium and was correlated with the area at risk defined by postmortem staining. The diagnostic quality of 18FDG and 13N-ammonia microPET images was good to excellent; the images were easily assembled into polar maps. In group 1, regional (18)F concentrations by microPET and postmortem were correlated linearly (r=0.99; P<0.01 for average and r=0.97; P<0.01 for regional concentrations). In group 2, perfusion defect sizes by microPET and postmortem were correlated linearly (P<0.01; r=0.93).

CONCLUSIONS

The findings indicate the feasibility of noninvasive studies of the myocardium in rats with a dedicated small-animal PET-imaging device.

[Myocardial fatty acid imaging with 123I-BMIPP in patients with chronic right ventricular pressure overload: clinical significance of reduced uptake in interventricular septum]

Regionally reduced 123I-BMIPP uptake in the interventricular septum (SEP) is observed in some patients with chronic right ventricular (RV) pressure overload. We studied the significance of this finding by comparing it with mean pulmonary arterial pressure (mPAP). 123I-BMIPP SPECT imaging was carried out in 21 patients with pulmonary hypertension (PH; 51(+)-14 years; 11 men and 10 women; 7 with primary pulmonary hypertension, 11 with pulmonary thromboembolism, and 3 with atrial septal defect). mPAP ranged from 25 to 81 mmHg (49 +/- 16 mmHg). Using a midventricular horizontal long-axis plane, regional BMIPP distributions in the RV free wall and SEP were estimated by referring to those in the LV free wall. Count ratios of the RV free wall and SEP to the LV free wall (RV/LV, SEP/LV) were determined by ROI analysis. RV/LV showed a linear correlation with mPAP (r = 0.42). However, SEP/LV was inversely correlated with mPAP (r = -0.49). When SEP/RV was compared among three regions of SEP in each patient, basal SEP/RV was most sensitively decreased in response to increased mPAP (r = -0.70). These results suggest that the assessment of septal tracer uptake in 123I-BMIPP SPECT imaging is useful for evaluating the severity of RV pressure overload in patients with PH.

Quantitative analysis of lung perfusion in patients with primary pulmonary hypertension

The aim of this study was to evaluate quantitatively the heterogeneity of lung perfusion scans in patients with primary pulmonary hypertension (PPH) and to compare it with the severity of disease.

METHODS

Lung perfusion scans were obtained on 22 patients with PPH and 12 age-matched control subjects. The perfused area rates (PARs) were calculated by dividing the lung area in each 10% threshold width from 10% to 100% of maximal counts by total lung area. The total absolute difference in the PAR between each patient and the mean control value was assumed as the perfusion index of the lung (P index). The P index was compared with hemodynamic parameters and the right ventricular ejection fraction (RVEF), including 7 patients who received long-term vasodilator therapy.

RESULTS

The P index correlated significantly with mean pulmonary arterial pressure (P < 0.001) and RVEF (P < 0.05). In patients with vasodilator therapy, the P index was improved significantly after therapy (P < 0.05) and was associated with a reduction in pulmonary arterial pressure.

CONCLUSION

Quantitative assessment of lung perfusion irregularity might provide useful information about the severity of disease and the effect of therapy in addition to the routine visual representation.