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Annals of Nuclear Medicine (v.24, #1)

Development of motion correction technique for cardiac ¹⁵O-water PET study using an optical motion tracking system by Kazuhiro Koshino; Hiroshi Watabe; Shinji Hasegawa; Takuya Hayashi; Jun Hatazawa; Hidehiro Iida (pp. 1-11).

Cardiac ¹⁵O-water PET studies provide an accurate quantitation of regional myocardial blood flow (rMBF). We developed a motion correction system using an optical motion-tracking device to detect a subject’s global movement for cardiac study.PET studies were carried out on a cardiac phantom and a healthy volunteer at rest. The three-dimensional locations of the markers attached to the subjects during scans were measured using an optical motion-tracking system. In the phantom study, we performed a transmission scan and seven ¹⁸F emission scans of a baseline and with artificial misalignment of shifts and rotations. The correlation coefficients between the baseline and the other images before and after the corrections for the misalignment were calculated. In the human study, we performed a ¹⁵O-water dynamic scan with a transmission and axially 30 mm-shifted transmission scans. Motion of the subject was estimated by the information from the system, and was corrected on each sinogram using attenuation maps realigned to dynamic frames. Reconstructed dynamic images were then realigned to the transmission data. We calculated rMBF values for nine segments and myocardial images from the emission images, which were reconstructed with the first attenuation map (reference) and with the misaligned attenuation map before and after our corrections.In the phantom study, the correlation coefficients were improved from 0.929 ± 0.022 to 0.987 ± 0.010 (mean ± SD) after the corrections. In the human study, the global and cyclic movements were detected. The cyclic movement due to respiration was smoothed by frame-averaging, and reasonable information of the global movement was obtained. The rMBF value (mean ± SD) was 0.94 ± 0.12 mL/min/g for the reference. The rMBF values using the misaligned attenuation map changed from 1.03 ± 0.21 to 0.93 ± 0.11 mL/min/g after the correction, and spurious defects in myocardial images were also recovered.Our technique provided reasonable information for correcting the global movement of the subject. It was shown that this system was applicable to detect and correct subject movement in cardiac PET studies at rest.

Keywords: Myocardial blood flow; PET; Motion correction; Attenuation correction; ¹⁵O-labeled water

Study on biodistribution and imaging of radioiodinated arginine-arginine-leucine peptide in nude mice bearing human prostate carcinoma by Mingming Yu; Haizhong Zhou; Xiaoqiang Liu; Ying Huo; Yalin Zhu; Yuehua Chen (pp. 13-19).

To investigate the biodistribution and imaging of ¹³¹I-labeled arginine-arginine-leucine (RRL) peptide in human prostate carcinoma bearing nude mice.The 10-mer cyclic peptide containing the RRL sequence (YCGGRRLGGC) was synthesized by the solid-phase method. Disulfide bonds between the cysteines maintain the cyclic structure. Radioiodination of the RRL peptide was performed by the chloramine-T method. ¹³¹I-labeled peptides were injected into the nude mice bearing human prostate carcinoma via a tail vein. Biodistribution and imaging results in vivo were obtained.The ¹³¹I-labeling rate of RRL peptide was about 60%. The radiochemical purity was 96.5%. The radiochemical purity of the labeled compound remained 90.3% at 24 h in human blood serum at 37°C. In the biodistribution studies, radiolabeled RRL peptide probe accumulated in the tumor to a level of approximately 2.52 and 0.65% injected dose per gram of tissue at 6 and 24 h after administration. The data for the ¹³¹I-labeled control peptide were 0.73 and 0.06% ID/g at 6 and 24 h after administration. The ratios of radioactivity in tumors to radioactivity in blood at 1, 6, and 24 h after injection were about 0.32, 1.12, 1.30 for RRL peptide and 0.30, 0.37, 0.22 for control peptide. The ratios of radioactivity in tumors to radioactivity in muscle at 1, 6, 24 h after injection were about 1.40, 3.94, 9.08 for RRL peptide and 1.98, 2.89, 1.78 for control peptide. At 24 h after administration, the SPECT imaging obtained clearly showed a contrasting tumor on the right armpit of mice with high concentrations of radioactivity, and the surrounding background was very low.The results suggest that radioiodination of RRL peptide is feasible and that the labeled compound is stable in human blood serum. The ¹³¹I-labeled RRL peptide shows high tumor uptake and good tumor-to-organ ratios that allow noninvasive visualization of tumors. The ¹³¹I-labeled compound is valuable to detect tumors as molecular probe.

Keywords: Arginine-arginine-leucine peptide; Tumor; Biodistribution; Imaging

¹⁸F-FDG PET imaging of progressive massive fibrosis by Soo Yoon Chung; Jae Hoon Lee; Tae Hoon Kim; Sang Jin Kim; Hyung Joong Kim; Young Hoon Ryu (pp. 21-27).

This study was to evaluate ¹⁸F-FDG PET features of progressive massive fibrosis (PMF) and to determine the ability of FDG PET to differentiate pure PMF from PMF-associated lung cancer. ¹⁸F-FDG PET and chest computed tomography (CT) scans were performed in 9 patients with pneumoconiosis and PMF. Patients who showed active pulmonary tuberculosis on CT scan were excluded. Pure PMF was confirmed via either fine needle aspiration biopsy (n = 6) or 12 months follow-up CT scan (n = 3). CT features and PET findings were evaluated for distribution of fibrotic masses, consolidations, and nodules on CT scan and mean and maximum standardized uptake values (SUVs) of abnormalities depicted on PET scan.14 masses were detected from nine patients. On chest CT scan, PMF masses were noted with surrounding small nodules and distortion of parenchyma. The size of the lesions ranged from 1.2 to 6.4 cm in maximum diameter. FDG PET scans identified metabolically active lesions in all patients. Maximal SUV ranged from 3.1 to 14.6 and mean SUV ranged from 1.4 to 8.5.FDG PET can identify PMF lesions as hypermetabolic lesions even without associated malignancy or tuberculosis. Therefore, it might have a limited role in the diagnosis of PMF with possible concurrent granulomatous inflammation or lung cancer.

Keywords: Progressive massive fibrosis; Pneumoconiosis; Lung cancer; ¹⁸F-FDG PET; Chest CT

Gallbladder ejection fraction measured by fatty meal cholescintigraphy: is it affected by extended gallbladder emptying data acquisition time? by Kusai M. Al-Muqbel (pp. 29-34).

The main objective of this study was to determine the effect of gallbladder emptying acquisition time on gallbladder ejection fraction (GBEF) measurement obtained by fatty meal cholescintigraphy (CS).During fatty meal cholescintigraphy (CS), GBEF1 and GBEF2 were calculated 20 and 45 min, respectively, post meal ingestion on 50 healthy volunteers, 37 patients with chronic acalculous cholecystitis (CAC) and 20 non-CAC patients. GBEF1/GBEF2 was calculated and represented the percentage of GBEF occurred during 20 min after meal ingestion. The gallbladder was classified as ended pattern if it terminated contraction before the end of data acquisition or classified as continuous pattern if it continued to contract before the end of data acquisition. Mean GBEF in continuous pattern was compared with mean GBEF in ended pattern in each group.Gallbladder emptying had two phases; early rapid phase and late slow phase. About two-thirds of ejected volume occurred within the rapid phase. About half of gallbladders in each group were classified as ended pattern while the other half was classified as continuous pattern. There was no significant difference in mean GBEF values between both patterns in each group.GBEF measurement obtained by CS is not affected by further extension of gallbladder emptying data acquisition beyond the standard 45–60 min acquisition time.

Keywords: Fatty meal; CCK; Time–activity curve; Acquisition time; Chronic acalculous cholecystitis

Incidental detection of Sertoli–Leydig cell tumor by FDG PET/CT imaging in a patient with androgen insensitivity syndrome by Tamer Özülker; Tevfik Özpaçacı; Filiz Özülker; Ümit Özekici; Remziye Bilgiç; Meral Mert (pp. 35-39).

A 29-year-old female patient who was being followed up for differentiated papillary thyroid carcinoma was referred to us for exploration of any possible metastasis since her serum thyroglobulin levels were high. The patient underwent an F-18 fluorodeoxyglucose positron emission tomography study, and a pathologically increased FDG uptake at the left lower abdomen was detected corresponding to a solid, cystic lesion on CT images. The patient had a history of primary amenorrhea and, together with the magnetic resonance imaging findings of absent uterus, short and blind end vagina, a diagnosis of androgen insensitivity syndrome was made. The patient underwent laparoscopic left pelvic mass resection, and the histopathology of the lesion revealed Sertoli–Leydig cell tumor.

Keywords: Sertoli–Leydig cell tumor; Androgen insensitivity syndrome; FDG PET

Incidental finding of an ¹¹C-acetate PET-positive multiple myeloma by Sang Mi Lee; Tae Sung Kim; Jeong Won Lee; Hyun Woo Kwon; Yong Il Kim; Se Hun Kang; Seok Ki Kim (pp. 41-44).

Multiple myeloma is a malignancy of plasma cells. The ¹⁸F-FDG PET findings of multiple myeloma have been reported previously. However, the ¹¹C-acetate PET findings have not been clarified. Here, we report a case of multiple myeloma detected with ¹¹C-acetate PET in a 51-year-old male patient with known hepatocellular carcinoma. The patient was admitted for management of a pathologic fracture of the right tibia. Imaging workup including X-ray, magnetic resonance image, bone scintigraphy; ¹⁸F-FDG led to a suspicion of metastatic bony lesions. Further, these lesions showed increased uptake on ¹¹C-acetate PET. Wide excision of the right tibia was performed, and histopathological examination of the lesion confirmed multiple myeloma. This case illustrates the characteristic ¹¹C-acetate PET findings of multiple myeloma.

Keywords: Multiple myeloma; ¹⁸F-fluorodeoxyglucose; ¹¹C-acetate; PET

Correlation analysis of measurement result between accelerator mass spectrometry and gamma counter by Ryogo Minamimoto; Yoshimi Hamabe; Chao Cheng; Marika Shimoda; Takashi Oka; Tomio Inoue (pp. 45-52).

The guidelines for microdosing in clinical trials were published in Japan in 2008 following the guidelines of the European Medicines Agency and the Food and Drug Administration. They recommend utilizing accelerator mass spectrometry (AMS) and positron emission tomography as candidates for monitoring drug metabolites in preclinical studies. We correlate the two methods by measuring appropriately labeled tissue samples from various mouse organs using both AMS and gamma counter.First, we measured the ¹⁴C background levels in mouse organs using the AMS system. We then clarified the relationship between AMS and gamma counter by simultaneously administering ¹⁴C-2-fluoro-2-deoxyglucose (¹⁴C-FDG) and ¹⁸F-2-fluoro-2-deoxyglucose (¹⁸F-FDG). Tissue distribution was examined after 30 min, 1 h, 2 h and 4 h using the AMS system for ¹⁴C-FDG and gamma counter for ¹⁸F-FDG. Background ¹⁴C levels were subtracted from the data obtained with radiotracer administration.The background ¹⁴C concentration differed with tissue type measured. Background ¹⁴C concentration in mouse liver was higher than in other organs, and was approximately 1.5-fold that in blood. The correlation coefficient (r) of the measurements between AMS (¹⁴C-FDG) and gamma counter (¹⁸F-FDG) was high in both normal (0.99 in blood, 0.91 in brain, 0.61 in liver and 0.78 in kidney) and tumor-bearing mice (0.95 in blood and 0.99 in tumor). The clearance profile of ¹⁸F-FDG was nearly identical to that of ¹⁴C-FDG measured with AMS.Accelerator mass spectrometry analysis has an excellent correlation with biodistribution measurements using gamma counter. Our results suggest that the combination of AMS and PET can act as a complementary approach to accelerate drug development.

Keywords: Accelerator mass spectrometry (AMS); Background; Positron emission tomography (PET); Correlation; Microdosing

Erratum to: Improvement of the diagnostic accuracy of lymph node metastases of colorectal cancer in ¹⁸F-FDG-PET/CT by optimizing the iteration number for the image reconstruction by Kazumasa Inoue; Takashi Sato; Hideaki Kitamura; Masaaki Ito; Yoshiyuki Tsunoda; Akira Hirayama; Hideo Kurosawa; Takashi Tanaka; Masahiro Fukushi; Noriyuki Moriyama; Hirofumi Fujii (pp. 53-53).

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Annals of Nuclear Medicine (v.24, #1)

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Annals of Nuclear Medicine (v.24, #1)