Study of Attenuation Correction Using a Cardiac Dynamic Phantom: Synchronized Time-Phase-Gated Attenuation Correction Method.

In cardiac nuclear medicine examinations, absorption in the body is the main factor in the degradation of the image quality. The Chang and external source methods were used to correct for absorption in the body. However, fundamental studies on attenuation correction for electrocardiogram (ECG)-synchronized CT imaging have not been performed. Therefore, we developed and improved an ECG-synchronized cardiac dynamic phantom and investigated the synchronized time-phase-gated attenuation correction (STPGAC) method using ECG-synchronized SPECT and CT images of the same time phase. Methods: As a basic study, SPECT was performed using synchronized time-phase-gated (STPG) SPECT and non-phase-gated (NPG) SPECT. The attenuation-corrected images were, first, CT images with the same time phase as the ECG waveform of the gated SPECT acquisition (with CT images with the ECG waveform of the CT acquisition as the reference); second, CT images with asynchronous ECG; third, CT images of the 75% region; and fourth, CT images of the 40% region. Results: In the analysis of cardiac function in the phantom experiment, left ventricle ejection fraction (heart rate, 11.5%-13.4%; myocardial wall, 49.8%-55.7%) in the CT images was compared with that in the STPGAC method (heart rate, 11.5%-13.3%; myocardial wall, 49.6%-55.5%), which was closer in value to that of the STPGAC method. In the phantom polar map segment analyses, none of the images showed variability (F (10,10) < 0.5, P = 0.05). All images were correlated (r = 0.824-1.00). Conclusion: In this study, we investigated the STPGAC method using a SPECT/CT system. The STPGAC method showed similar values of cardiac function analysis to the CT images, suggesting that the STPGAC method accurately reconstructed the distribution of blood flow in the myocardial region. However, the target area for attenuation correction of the heart region was smaller than that of the whole body, and changing the gated SPECT conditions and attenuation-corrected images did not affect myocardial blood flow analysis.

Assessment of patient exposure to X-radiation from SPECT/CT scanners.

UNLABELLED: In the operation of any SPECT/CT system, in addition to internal radiation exposure (gamma-ray) resulting from administration of radiopharmaceuticals, external radiation exposure (x-ray) from the CT device has to be taken into consideration in the light of recommendations from the International Commission on Radiological Protection. These recommendations include justification of practices (the use of radiation produces sufficient benefit to offset any risks caused by the use of radiation), optimization (the incurred exposure by the use of radiation should be kept as low as reasonably achievable), and dose limitation. The internal radiation exposures of each organ after administration of radiopharmaceuticals are calculated by the MIRD Committee method. For example, the internal radiation exposure index for brain perfusion scintigraphy is 0.8 mGy/37 MBq for N-isopropyl-4-iodoamphetamine((123)I) hydrochloride or 0.19 mGy/37 MBq for ethyl cysteinate dimer. On the other hand, the external radiation exposure from a CT device is calculated using the CT dose index volume (CTDIvol)--a measured and calculated value unique to the CT scanner and scan parameters used--and a dose-length product, which is obtained from CT conditions and generally used as a reference value for CT radiation exposure. However, CTDIvol and dose-length product are calculated values unique to each device, not the value of external radiation exposures of each organ. Therefore, we believe that it is necessary to measure the total (internal plus external) radiation exposure dose from CT. In the present study, using an anthropomorphic phantom for deep-body total absorbed dose measurement, we evaluated the radiation exposure doses (organ-absorbed doses) of each organ under various CT conditions. METHODS: The radiation exposure doses of each organ were measured by inserting thermoluminescent dosimeter elements into the phantom under various CT conditions. RESULTS: The following were brain radiation exposure doses in the head region. For 90 kVp and 25 mAs, 1.39 mGy (CTDIvol, 1.8 mGy), for 90 kVp and 300 mAs, 17.00 mGy (CTDIvol, 21.2 mGy), for 120 kVp and 25 mAs, 3.21 mGy (CTDIvol, 3.8 mGy), for 120 kVp and 300 mAs, 37.79 mGy (CTDIvol, 47.7 mGy), for 140 kVp and 25 mAs, 5.08 mGy (CTDIvol, 5.5 mGy), and for 140 kVp and 300 mAs, 65.07 mGy (CTDIvol, 65.6 mGy). The eye radiation exposure doses were as follows. For 90 kVp and 25 mAs, 1.94 mGy (CTDIvol, 1.8 mGy), for 90 kVp and 300 mAs, 20.31 mGy (CTDIvol, 21.2 mGy), for 120 kVp and 25 mAs, 3.71 mGy (CTDIvol, 3.8 mGy), for 120 kVp and 300 mAs, 49.72 mGy (CTDIvol, 47.7 mGy), for 140 kVp and 25 mAs, 5.44 mGy (CTDIvol, 5.5 mGy), and for 140 kVp and 300 mAs, 69.76 mGy (CTDIvol, 65.6 mGy). In addition, the radiation exposure doses of the cervical, thoracic, abdominal, and pelvic regions were measured in detail. CONCLUSION: Our estimated external radiation exposure doses (x-ray) of each organ under various CT conditions, along with the internal radiation exposure doses (gamma-ray) resulting from the administration of radiopharmaceuticals, seem to be useful as reference values in understanding the radiation exposure doses for performing various nuclear medicine examinations.

Considerations for setting up an order entry system for nuclear medicine tests.

UNLABELLED: Integrating the Healthcare Enterprise-Japan (IHE-J) was established in Japan in 2001 and has been working to standardize health information and make it accessible on the basis of the fundamental Integrating Healthcare Enterprise (IHE) specifications. However, because specialized operations are used in nuclear medicine tests, online sharing of patient information and test order information from the order entry system as shown by the scheduled workflow (SWF) is difficult, making information inconsistent throughout the facility and uniform management of patient information impossible. Therefore, we examined the basic design (subsystem design) for order entry systems, which are considered an important aspect of information management for nuclear medicine tests and needs to be consistent with the system used throughout the rest of the facility. METHODS: There are many items that are required by the subsystem when setting up an order entry system for nuclear medicine tests. Among these items, those that are the most important in the order entry system are constructed using exclusion settings, because of differences in the conditions for using radiopharmaceuticals and contrast agents and appointment frame settings for differences in the imaging method and test items. CONCLUSION: To establish uniform management of patient information for nuclear medicine tests throughout the facility, it is necessary to develop an order entry system with exclusion settings and appointment frames as standard features. Thereby, integration of health information with the Radiology Information System (RIS) or Picture Archiving Communication System (PACS) based on Digital Imaging Communications in Medicine (DICOM) standards and real-time health care assistance can be attained, achieving the IHE agenda of improving health care service and efficiently sharing information.

Thalamic hyperperfusion in verbal hallucination of Parkinsonian patients.

OBJECTIVE: We compared brain perfusion image using 3D-SSP analysis of (123)I-IMP SPECT between Parkinson's disease patients with auditory verbal hallucination and those without auditory hallucination. METHODS: Eighty-three cases with Parkinson's disease were studied. In 6 of these patients, auditory hallucination was noted. Among them, four cases had verbal hallucination and two other cases had elementary hallucination. Auditory hallucination was not found in the other 77 cases. RESULTS: Right thalamic perfusion was significantly increased in the verbal hallucination group compared to the group that lacked auditory hallucination. CONCLUSION: In Parkinson's disease, the right thalamic hyperactive state may be related to verbal hallucination.

Subtraction SPECT for parathyroid scintigraphy based on maximization of mutual information.

UNLABELLED: Our objective was to investigate the feasibility of subtraction for SPECT images of (99m)Tc-MIBI double-phase parathyroid scintigraphy. METHODS: Fourteen patients with hyperparathyroidism were enrolled in the present study. Histopathologically, excised tissue specimens showed hyperplasia in 11 patients and adenoma in 3 patients. Both ultrasonography and (99m)Tc-sestamibi (MIBI) SPECT images were obtained from all patients. As standard lines to ensure that patient positioning remained identical between the different phases, we used the cross-marker produced by a pair of laser pointers, the orbitomeatal line, and the vertical midline through the patient's nose. Data processing was performed with software that enables image registration by maximization of mutual information. The results of subtraction SPECT imaging were compared with those of ultrasonography. RESULTS: The registration of double-phase SPECT images was successful in all patients when the salivary glands were excluded from the image reconstruction region. The overall sensitivities of scintigraphy and ultrasonography were 90.9% (40/44) and 70.5% (31/44), respectively, with respective specificities of 83.3% (10/12) and 75.0% (9/12). Scintigraphy and ultrasonography showed accuracies of 92.8% (52/56) and 71.4% (40/56), respectively. CONCLUSION: The new technique used in the present study allowed the subtraction for SPECT images. The sensitivity of parathyroid lesion detection using this technique was superior to that of ultrasonography.

[Survey of the current state of order-entry systems in the nuclear medicine field].

BACKGROUND AND OBJECTIVES: In the "Grand Design for Computerization of the Medical Field" of December, 2001, the Ministry of Health, Labour and Welfare set a numerical target for the adoption of electronic medical charts nationwide in at least 60% hospitals with 400 or more beds. Therefore, the introduction and operation of an order-entry system, which is necessary for establishing electronic medical charts, became essential for each of these medical facilities. We surveyed the current state of order-entry systems for nuclear medicine, which are considered difficult to introduce owing to the particulars of their operation, and herewith report the results. METHODS: Questionnaires with a request for cooperation were sent by mail to 119 facilities nationwide that are engaged in nuclear medicine. The questionnaire surveyed 21 items, including operational status and restrictions of the order-entry system. RESULTS: The absolutely essential restriction settings for the introduction and operation of an order-entry system were not being used, and the scheduling of tests was being conducted on the basis of human judgment. CONCLUSION: The development of an order-entry system that includes standardization of basic specifications (restrictions) according to the content and work are necessary for nuclear scans, for which the introduction and operation of an order-entry system can cause concern owing to the particulars of operation in the field of radiation.

Heterogeneous factors in dementia with Parkinson's disease: IMP-SPECT study.

BACKGROUND: Nature of the dementing process in Parkinson's disease, and particularly its relationship with Alzheimer's disease, diffuse Lewy body disease or frontal dementia remains controversial. OBJECTIVE: We hypothesize that origins of dementia in Parkinson's disease are heterogeneous, so we compared cortical regional cerebral blood flow (rCBF) between Parkinson's disease patients with and without dementia. PATIENTS: Forty consecutive patients with Hoehn-Yahr stage III or IV Parkinson's disease were used (13 patients had dementia (PDD group), and 27 patients had no dementia (PDND group)). RESULTS: There were significant rCBF reductions in the left parietal association cortex and left frontal association cortex in PDD. Multiple logistic regression analysis demonstrated that only rCBF of the left frontal association cortex was significant. PDD patients were divided into three groups according to rCBF patterns: frontal hypoperfusion group, Alzheimer's disease-like group, and diffuse Lewy body disease-like group. CONCLUSIONS: Controversial study results involving PDD patients may be mainly due to heterogeneity in dementing processes in Parkinson's disease.

Hypoperfusion of the auditory and prefrontal cortices in Parkinsonian patients with verbal hallucinations.

We examined patients with and without auditory hallucinations, using n-isopropyl-p-[123I]iodoamphetamine single photon emission computed tomographic imaging. We assessed verbal hallucinations in the present study: patients with nonverbal auditory hallucinations were excluded. A total of 11 patients with verbal and visual hallucinations and 17 patients with visual hallucinations only were enrolled. Patients with both verbal and visual hallucinations revealed significant hypoperfusion in the bilateral prefrontal cortex and right superior temporal gyrus compared to patients with visual hallucinations only. There were no significant hyperperfusion in patients with verbal plus visual hallucinations. These results may support the release hallucination theory in verbal hallucinations of Parkinson's disease, although another explanations may be more appropriate and further studies are required.

Hypoperfusion of the visual pathway in parkinsonian patients with visual hallucinations.

Little is known about the developing mechanisms of visual hallucinations in Parkinson's disease. This study aimed to investigate perfusion changes in parkinsonian patients with visual hallucinations using n-isopropyl-p-[123I]iodoamphetamine ([123I]IMP) single photon emission computed tomography imaging. A total of 70 consecutive patients, including 31 patients with visual hallucinations, and 39 patients without hallucinations, participated in this study. Patients with severe cognitive impairment (Mini-Mental State Examination score < 20), nonvisual hallucinations, or confusion were excluded. We compared brain perfusion changes between the two groups. We found that hallucinatory patients had significant perfusion reductions in the bilateral inferior parietal lobule, inferior temporal gyrus, precuneus gyrus, and occipital cortex compared to nonhallucinatory patients. These results suggested that hypoperfusion of the visual pathway was closely related to visual hallucinations in Parkinson's disease.

Excessive daytime sleepiness in Parkinson disease: a SPECT study.

STUDY OBJECTIVES: The underlying pathologic mechanism of excessive daytime sleepiness (EDS) in Parkinson disease and the relative contributions of brain function to this process are poorly understood. We compared brain perfusion images between patients with Parkinson disease and EDS and those without EDS using n-isopropyl-p-1231 iodoamphetamine single photon emission computed tomography. DESIGN: Clinical study. SETTING: Sumitomo Hospital. PATIENTS: Thirteen patients with Parkinson disease with EDS (EDS group) and 27 patients with Parkinson disease without EDS (no-EDS group) were studied. Whether or not each case had EDS was determined according to the response to the Epworth Sleepiness Scale: patients with an Epworth Sleepiness Scale score > or = 10 were included in the EDS group, and patients with an Epworth Sleepiness Scale score < or = 9 were included in the no-EDS group. MEASUREMENTS AND RESULTS: There were significant hypoperfusions in the left parietal and temporal association cortex in the EDS group. In the multivariable logistic regression model, attention and decreased regional cerebral blood flow of the left parietal association cortex and right caudate and increased regional cerebral blood flow of the right thalamus were the independent and significant factors. CONCLUSIONS: The cortical hypofunction relative to hyperfunction of the brain stem may relate to EDS in Parkinson disease. This is the first imaging study about EDS in Parkinson disease, and further studies are required.

Wisconsin Card Sorting Test and brain perfusion imaging in Parkinson's disease.

BACKGROUND: Few imaging studies investigated frontal dysfunctions in Parkinson's disease. OBJECTIVES: We investigated relationships between Wisconsin Card Sorting Test (WCST) and brain perfusion in patients with non-demented Parkinson's disease. METHODS: Patients were divided into two groups according to WCST score: (1) CA (number of category achieved)or=3. We performed three-dimensional stereotactic surface projection and volume of interest analysis using (123)I-IMP scintigraphy. RESULTS: Hypoperfusions of the bilateral posterior cingulate, rostrodorsal prefrontal, and left frontopolar cortices were shown in CA

Frontal assessment battery and brain perfusion image in Parkinson's disease.

The objective was to compare brain perfusion image using 3-dimensional stereotactic surface projection analysis of N-isopropyl-p-123I iodoamphetamine single photon emission computed tomography between Parkinson's disease patients with a high frontal assessment battery score and those with a low frontal assessment battery score. Thirty nondemented patients with Parkinson's disease were studied. Patients were divided into 2 groups: a high-scoring group whose frontal assessment battery score was 12 or more and a low-scoring group whose frontal assessment battery score was 11 or less. The high-scoring group included 21 patients, and the low-scoring group included 9 patients. They underwent N-isopropyl-p-123I iodoamphetamine single photon emission computed tomography, and we analyzed the data by the 3-dimensional stereotactic surface projection method. Results showed that left inferior parietal lobule and left supramarginal gyrus perfusion of the low-scoring group were significantly decreased compared with the high-scoring group. It is concluded that patients with Parkinson's disease may have frontal lobe dysfunction, but the decreased frontal assessment battery score may be caused not by progressed frontal lobe dysfunction but by parietal lobe dysfunction added to their preexisting frontal lobe impairment.

N-isopropyl-p- 123I iodoamphetamine single photon emission computed tomography study of Parkinson's disease with dementia.

BACKGROUND: Intellectual deterioration occurs in 10-40% of patients with Parkinson's disease. However, there are many conflicting studies on its relation with brain perfusion and the nature of this dementing process remains controversial. OBJECTIVE: To compare cortical perfusion by SPECT using (123)I-IMP between Parkinson's disease patients with dementia and those without dementia and to investigate the correlation between dementia in Parkinson's disease and brain perfusion in various areas. METHODS: Fifty-two cases of Parkinson's disease and 10 control cases were studied. The Parkinson's disease with dementia group included 30 cases and the Parkinson's disease without dementia group included 22 cases. RESULTS: By multiple logistic regression method, we demonstrated significant hypoperfusion in the occipital cortex in Parkinson's disease with dementia. CONCLUSIONS: The cause of dementia in Parkinson's disease may vary. We demonstrated that occipital hypoperfusion was closely correlated to dementia in Parkinson's disease compared to frontal, parietal and temporal perfusion.

Three-dimensional stereotactic surface projection study of freezing of gait and brain perfusion image in Parkinson's disease.

Gait disturbance is a cardinal symptom in patients with Parkinson's disease. Among the gait disturbances, freezing of gait is a unique and troublesome symptom, but its mechanism is unclear. We compared brain perfusion images using three-dimensional stereotactic surface projection analysis of N-isopropyl-p-123I iodoamphetamine single photon emission computed tomography between Parkinson's disease patients with freezing of gait and those without. Twenty-four cases (freezing of gait group) with Parkinson's disease with freezing of gait, and 31 Hoehn and Yahr stage-matched cases (no freezing of gait group) with Parkinson's disease without freezing of gait were studied. Bilateral Brodmann area 11 perfusion of the freezing of gait group decreased significantly compared to that of the no freezing of gait group. The Brodmann area 11 may play important roles in gait, and impairment in this region may have a close relationship with freezing of gait in Parkinson's disease.

Brain perfusion differences between Parkinson's disease and multiple system atrophy with predominant parkinsonian features.

BACKGROUND: The patterns of regional cerebral blood flow in Parkinson's disease and multiple system atrophy remain inconsistent. OBJECTIVES: To compare brain perfusion images of 123I-IMP SPECT between Parkinson's disease, multiple system atrophy with predominant parkinsonian features (MSA-P) and controls. METHODS: Eighty-two patients with Parkinson's disease, 10 patients with MSA-P and 14 controls were studied. We performed 3D-SSP and volume of interest analysis using 123I-IMP scintigraphy. RESULTS: Occipital perfusion of MSA-P increased compared to that of Parkinson's disease and perfusion in the cerebellum and primary sensorimotor cortex of Parkinson's disease increased compared to that of MSA-P. Perfusion in the putamen of MSA-P decreased compared to that of Parkinson's disease. CONCLUSION: Our study demonstrated perfusion differences in 123I-IMP SPECT between the two diseases.