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UNLABELLED The purpose of this study was to evaluate the relationship of body habitus, blood glucose level and injected dose, respectively, with BGO (Bi₄Ge₃O₁₂) positron emission tomography (PET) image quality using commercially available 2-deoxy-2-[¹⁸F] fluoro-D-glucose (FDG). We also evaluated the relationship between PET image quality and acquisition time for each weight group. METHOD One hundred twenty-five patients (66 male, 59 female) were enrolled in the study. We adopted liver signal-to-noise ratio (liver SNR) as an image quality index, derived from the region of interest (ROI) placed on the axial image of the liver. RESULTS The correlation coefficient between liver SNR and dose per weight was 0.502. The liver SNR indicated a negative relationship with body weight, body mass index (BMI) and cross sectional area of the patient's body, with the correlation coefficients of -0.594, -0.479 and -0.522, respectively. For all weight groups, an extended acquisition time of at least 60 s/bed was necessary to improve liver SNR. CONCLUSION The findings of this study are potentially of use for designing imaging protocols for the BGO-PET/CT system when using commercially available FDG. It is easy to obtain good image quality for patients of low to average body size with the standard injection dose. However, large patients should be injected, wherever possible, with an FDG dose of up to 5 MBq/kg. The acquisition time in overweight and obese patients should be as longer as possible than in standard weight patients.

From the difference of a clinical dose and the molarity of hepatic specificity contrast agent Gadoxetate Sodium (Gd-EOB-DTPA) and Meglumine Gadopentetate (Gd-DTPA), we make one’s own phantom this time, we performed a study of the base about contrast-to-noise ratio (CNR) of the three dimensional-fast spoiled gradient echo (3D-FSPGR) technique and an optimum flip angle (FA) and the bandwidth (BW) for Gd-DTPA dilution 0.3 mmol/l which assumed T1 value of the liver parenchyma of Gd-DTPA dilution 6.0 mmol/l and Gd-EOB-DTPA dilution 1.5 mmol/l which assumed large arterial blood maximum density of first pass in Dynamic study. We assume CNR of FA10˚ in each BW criteria, CNR of Gd-DTPA dilution 6.0 mmol/l becomes the 3.63–4.38 double at the maximum in FA30˚ with each BW; CNR of Gd-EOB-DTPA dilution 1.5mmol/l is with 1.95–2.36 double at the maximum in FA 20–25˚ with each BW. When CNR compares it with a value of FA becoming biggest, with each BW, as for Gd-EOB-DTPA dilution 1.5 mmol/l, about around 40% CNR lowered for Gd-DTPA dilution 6.0 mmol/l. In Dynamic study in Gd-EOB-DTPA, we did not use an imaging condition totally same as Gd-DTPA and understood that we required the setting of the imaging condition that considered the influence of the T1 relaxation time by the difference of a clinic dose and the molarity in first pass.

The purpose of this study was to evaluate the relationship of body habitus, blood glucose level and injected dose, respectively, with BGO (Bi₄Ge₃O₁₂) positron emission tomography (PET) image quality using commercially available 2-deoxy-2-[¹⁸F] fluoro-D-glucose (FDG). We also evaluated the relationship between PET image quality and acquisition time for each weight group.One hundred twenty-five patients (66 male, 59 female) were enrolled in the study. We adopted liver signal-to-noise ratio (liver SNR) as an image quality index, derived from the region of interest (ROI) placed on the axial image of the liver.The correlation coefficient between liver SNR and dose per weight was 0.502. The liver SNR indicated a negative relationship with body weight, body mass index (BMI) and cross sectional area of the patient's body, with the correlation coefficients of -0.594, -0.479 and -0.522, respectively. For all weight groups, an extended acquisition time of at least 60 s/bed was necessary to improve liver SNR.The findings of this study are potentially of use for designing imaging protocols for the BGO-PET/CT system when using commercially available FDG. It is easy to obtain good image quality for patients of low to average body size with the standard injection dose. However, large patients should be injected, wherever possible, with an FDG dose of up to 5 MBq/kg. The acquisition time in overweight and obese patients should be as longer as possible than in standard weight patients.

The aim of this study was to assess the exposure dose value (DLP) displayed on the operator console in a computed tomography system with automatic exposure control (CT-AEC) which decides the exposure dose from a positioning image. We measured exposure dose with two kinds of CT systems and evaluated the error of the displayed DLP value on the operator console against the measured DLP value. The assessment was performed in three sites: head and neck, upper chest, and lower abdomen. As a result, the errors of displayed value with CT-AEC against the error without CT-AEC in system A (4.09%) were significantly different on two assessment sites (head and neck: -4.02%, upper chest: 6.60%). There is no significant difference on the third assessment site (lower abdomen: 0.06%). On the other hand, those values in system B (8.38%) were almost similar with no significant differences (head and neck: -1.12%, upper chest: -1.85%, lower abdomen: -0.64%). The results show that there were significant differences noted between the errors of displayed value with CT-AEC and without CT-AEC in system A for the head and neck and the upper chest. In conclusion, displayed value with CT-AEC and without CT-AEC were about the same error. However, the possibility that the error depended on a model and the examination site of CT was shown.

We studied the position dependent influence that sensitivity correction processing gave the signal-to-noise ratio (SNR) measurement of parallel imaging (PI). Sensitivity correction processing that referred to the sensitivity distribution of the body coil improved regional uniformity more than the sensitivity uniformity correction filter with a fixed correction factor. In addition, the position dependent influence to give the SNR measurement in PI was different from the sensitivity correction processing. Therefore, if we divide SNR of the sensitivity correction processing image by SNR of the original image in each pixel and calculate SNR ratio, we can show the position dependent influence that sensitivity correction processing gives the SNR measurement in PI. It is with an index of the sensitivity correction processing precision.

To evaluate bone metastasis from hepatocellular carcinoma (HCC), both bone and 99mTc-HM-PAO scintigraphies were performed in six patients with clinically and pathologically confirmed HCC. Two patients had a bone scintigram which revealed abnormal accumulation in the skull base, pelvic bone and thoracic spine. The 99mTc-HM-PAO scans of both these patients also showed abnormal accumulation in the same sites. The bone scintigrams in one patient revealed not only abnormal accumulation in the ribs but also photon deficient areas in the sternum, thoracic spine and femur, while 99mTc-HM-PAO scans showed abnormal accumulation in all these sites. In three patients, bone scintigraphy revealed photon deficient areas in the ribs, pelvic bone and femur, and their 99mTc-HM-PAO scintigrams showed abnormal accumulation in the same sites. Thus, it was shown that, in the detection of bone metastasis from HCC by means of bone scintigraphy, it was necessary to pay attention to hot and cold lesions, and that a combination study with 99mTc-phosphorous compounds and 99mTc-HM-PAO was useful in evaluating these lesions.

To improve the scintigraphic differential diagnosis of thyroid nodules, Tc-99m pertechnetate-Tl-201 Cl subtraction scintigraphy (Tc-Tl subtraction scanning) was performed in 106 patients with various histologically proven thyroid nodules. Results were evaluated by comparison with surgical findings and preoperative ultrasonographic results. Thyroid nodules were more successfully detected by Tc-Tl subtraction scanning than by either Tc-99m pertechnetate or Tl-201 Cl scintigraphy alone. Detection of nodules was further improved when images recorded by the three methods were integrally observed (sensitivity 83%, accuracy 89%), with detectability approaching that of ultrasonography. False-positive or -negative Tc-Tl subtraction scans were obtained principally when multiple nodules were present (7 cases) or when no discrepancy existed between the accumulations of Tc-99m pertechnetate and Tl-201 Cl (18 cases). Most colloid nodules exhibited irregular margins, heterogeneous internal accumulations of Tl-201 Cl, and distorted shapes on Tc-Tl subtraction scans, while the majority of adenoma were oval-shaped with smooth margins. Carcinoma were characterized by homogeneous internal accumulation of Tl-201 Cl and distorted shapes.

Two patients with polymyositis showed abnormal muscular uptake of Tc-99m-methylene diphosphonate (MDP) during routine bone imaging. Imaging with Tc-99m MDP is a useful tool in monitoring the activity of the diseased muscle.

A newly developed dual photon absorptiometry system (DCS-600, ALOKA Co., LTD.) using two monochromatic X-rays for the determination of bone mineral in the peripheral bone was fundamentally studied, in comparison to single photon absorptiometry system (SPA). The accuracy and precision in DCS-600 were equal to or better than SPA system. Furthermore, in DCS-600 the forearm could be imaged, and the manipulation was easy. Thus DCS-600 was found to be a good instrument as a quantifying system of bone mass.

We used a combination of bone and bone-marrow scintigraphy to study 25 patients with prostatic cancer. Of the 18 cases whose 99mTc-methylene diphosphonate (MDP) bone scans showed hot spots in the lower lumbar region of the spine and/or the pelvic bone, 8 had normal bone-marrow scintigrams. These 8 patients were subsequently shown to have senile, degenerative changes of the spine. On the other hand, in 9 of the 10 patients whose bone-marrow scintigrams showed accumulation defects, follow-up study and characteristic X-ray findings confirmed the presence of metastases. In all 6 cases with extensive bone metastases shown by 99mTc-MDP bone scintigraphy, 99mTc-sulphur-colloid bone-marrow scintigraphy showed multiple accumulation defects. In conclusion, bone-marrow scintigraphy was found to be useful in distinguishing metastatic lesions from benign degenerative changes in the cases with suspected bone involvement, as well as in evaluating equivocal lesions in the pelvis.

Lymphoscintigraphy with SC injection of 67Ga-citrate was carried out on patients with lymph node metastasis and malignant lymphoma. The dose given at each injection site was about 200 muCi and scintigraphy was started about 5 min after injection. Metastatic lymph nodes and malignant lymphoma were successfully imaged. This positive delineation corresponded well to cold lesions detected by lymphoscintigraphy with 99mTc-rhenium colloid in metastatic lymph nodes. Hotter lesions in malignant lymphoma were scanned positively with 99mTc-rhenium colloid by this method. In in vitro studies, incorporation of 67Ga-citrate in HeLa S3 cells was about 4 times that in macrophages, when the incubation time was 1 h, while colloidal uptake by macrophages was 13 times that by HeLa S3 cells. The binding of 67Ga to transferrin in lymph and pinocytosis are suggested mechanisms of localization. A combination of colloid- and sc 67Ga-lymphoscintigraphy would be of value in the diagnosis of lymph node disease.

In a patient with synovial sarcoma, routine bone survey showed no abnormality, while bone marrow scintigraphy with Tc-99m sulfur colloid revealed a defect in the fifth lumbar vertebra. At surgery, tumorous invasion was noted in the fifth lumbar vertebra and the surrounding tissues. It was suggested that the bone marrow scintigraphy was particularly useful in the detection of tumorous invasion into the bone marrow at the early stage before the destruction of skeletal tissue.

Four patients with sternocostoclavicular hyperostosis showing characteristic abnormal uptake on bone imaging are described. Bone imaging was useful in the diagnosis of sternocostoclavicular hyperostosis.