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Annals of Nuclear Medicine (v.21, #7)
PET kinetic analysis: wavelet denoising of dynamic PET data with application to parametric imaging by Miho Shidahara; Yoko Ikoma; Jeff Kershaw; Yuichi Kimura; Mika Naganawa; Hiroshi Watabe (pp. 379-386).
Physiological functions (e.g., cerebral blood flow, glucose metabolism, and neuroreceptor binding) can be investigated as parameters estimated by kinetic modeling using dynamic positron emission tomography (PET) images. Imaging of these physiological parameters, called parametric imaging, can locate the regional distribution of functionalities. However, the most serious technical issue affecting parametric imaging is noise in dynamic PET data. This review describes wavelet denoising of dynamic PET images for improving image quality in estimated parametric images. Wavelet denoising provides significantly improved quality directly to dynamic PET images and indirectly to estimated parametric images. The application of wavelet denoising to radio-ligand and kinetic analysis is still in the development stage, but even so, it is thought that wavelet techniques will have a substantial impact on nuclear medicine in the near future.
Keywords: PET; Wavelet transform; Denoising; Parametric imaging; Kinetic analysis
N-isopropyl-4-[123I]iodoamphetamine (123I-IMP) products: a difference in radiochemical purity, unmetabolized fraction, and octanol extraction fraction in arterial blood and regional brain uptake in rats by Yasukazu Kanai; Shinji Hasegawa; Yasuyuki Kimura; Naohiko Oku; Hiroshi Ito; Hiroshi Fukuda; Jun Hatazawa (pp. 387-391).
N-isopropyl-4-[123I]iodoamphetamine (123I-IMP) is a lipophilic compound utilized for cerebral blood flow (CBF) measurement with single photon emission computed tomography (SPECT). Two different 123I-IMP products (IMPA and IMPB) are commercially available. We examined the radiochemical purity, unmetabolized fraction, and octanol extraction fraction in arterial blood, and the regional brain uptake of IMPA and IMPB in a rat model. IMPB (96.4% ± 0.08%, P < 0.05) showed significantly higher radiochemical purity than IMPA (95.5% ± 0.20%). The mean unmetabolized fraction in arterial blood taken at 10 min after intravenous administration of IMPB (69.5% ± 4.4%, P < 0.01) was significantly higher than that of IMPA (59.6% ± 2.6%). The mean octanol extraction fraction of IMPB (75.0% ± 1.3%, P < 0.01) was also significantly higher than that of IMPA (67.2% ± 0.8%). The mean levels of radioactivity in arterial blood sampled at 10 min after injection and mean regional brain radioactivity (cerebral cortices, basal ganglia, brain stem, and cerebellum) at 10–12 min after injection were not significantly different between IMPA and IMPB. The present study indicates differences in the radiochemical purity and the unmetabolized and octanol extraction fraction in arterial blood between the two commercially available 123I-IMP products. The appropriate octanol extraction fractions for IMPA and IMPB should be determined in humans and employed for quantitative CBF measurement in clinical SPECT.
Keywords: IMP; SPECT; CBF
Using 99mTc-DTPA radioaerosol inhalation lung scan as compared with computed tomography to detect lung injury in blunt chest trauma by Hidir Esme; Eser Kaya; Okan Solak; Yucel Yavuz; Yusuf Yurumez; Murat Sezer (pp. 393-398).
Detection of pulmonary contusion in patients with blunt chest trauma is very important so as to commence therapy immediately to avoid irreversible damage. The purpose of our study was to evaluate the efficacy of technetium-99m diethylene triamine pentaacetic acid (99mTc-DTPA) aerosol inhalation lung scintigraphy in comparison with chest computed tomography (CT) in the diagnosis of pulmonary contusion at acute blunt chest trauma.Twenty-nine patients with isolated blunt chest trauma were referred to the emergency department of our hospital, and nine healthy people participated in this study. Sixteen patients who had pulmonary contusion on CT scans were referred to as group 1, and 13 patients who had normal CT scans as group 2. Nine healthy people comprised a control group. 99mTc-DTPA aerosol inhalation lung scintigraphy was performed on the first day in all patients.The mean half time (T½) and penetration index values of 99mTc-DTPA clearance were significantly lower in groups 1 and 2 compared with the control group. Among the three groups, there were no significant differences in arterial blood gas analysis except for PO2. The mean T½ value of 99mTc-DTPA clearance did correlate with PO2 values but not with pH, PCO2, or HCO3 values. 99mTc-DTPA radioaerosol inhalation lung imaging may serve as a useful adjunct and supportive method to chest CT scanning for detecting mild pulmonary contusion.
Keywords: Blunt trauma; 99mTc-DTPA aerosol inhalation lung scintigraphy; Computed tomography
Prediction of cardiac events in patients with dilated cardiomyopathy using 123I-BMIPP and 201Tl myocardial scintigraphy by Aritomo Inoue; Shinichiro Fujimoto; Shohei Yamashina; Junichi Yamazaki (pp. 399-404).
Various clinical trials for dilated cardiomyopathy (DCM) have demonstrated that the prognosis as well as cardiac function is improved by the administration of beta-blocker therapy. On the other hand, 123I-betamethyl-p-iodophenyl-pentadecanoic acid (BMIPP) reflects myocardial fatty acid metabolism and is considered to be a more sensitive tracer than perfusion tracers. In this study, the efficacy of DCM for the evaluation of myocardial damage and the prediction of cardiac events was studied using 123I-BMIPP and 201TI (Tl) myocardial scintigraphy.Study subjects comprised 33 DCM patients, divided into a cardiac event group (event, n = 9) and an event-free group (event free, n = 24). An extent score (ES) and severity score (SS) were calculated for each BMIPP image. BMIPP and Tl images were divided into 17 segments, and total defect scores (TDS) were calculated for each. The TDS of the BMIPP and Tl images were compared with score differences greater than or equal to 4 and less than 4 defined as mismatch and non-mismatch, respectively.The TDS of BMIPP was significantly higher in the event group than in the event-free group (P < 0.05). The ES and SS were significantly higher in the event group than in the event-free group (P < 0.01). The comparison in the 2 × 2 contingency tables showed that the occurrence of non-mismatch was significantly higher in the event-free group (χ2 test; P < 0.01). The ES of BMIPP was a significant predictor of cardiac events in the multivariate analysis (P < 0.01).These results suggest that the ES for BMIPP is useful as a predictor of cardiac events in DCM.
Keywords: 123I-betamethyl-p-iodophenyl-pentadecanoic acid; Dilated cardiomyopathy; Cardiac prognosis; Mismatch
Normal uptake of 18F-FDG in the testis: an assessment by PET/CT by Kazuhiro Kitajima; Yuji Nakamoto; Michio Senda; Yumiko Onishi; Hiromi Okizuka; Kazuro Sugimura (pp. 405-410).
The aim of this study was to assess the physiological uptake of 18F-fluoro-2-deoxyglucose (FDG) by an apparently normal testis with combined positron emission tomography–computed tomography (PET/CT) and its correlation with age, blood glucose level, and testicular volume.The testicular uptake of 18F-FDG, expressed as the standardized uptake value (SUV), was measured on PET/CT images in 203 men. The correlation between SUV and age, blood glucose level, and testicular volume was assessed.The SUV in the total of 406 testes was 2.44 ± 0.45 (range 1.23–3.85). The SUV was 2.81 ± 0.43 (2.28–3.85) for 30–39 years (n = 12), 2.63 ± 0.45 (1.77–3.75) for 40–49 years (n = 64), 2.46 ± 0.35 (1.44–3.15) for 50–59 years (n = 82), 2.51 ± 0.41 (1.50–3.46) for 60–69 years (n = 86), 2.43 ± 0.47 (1.42–3.29) for 70–79 years (n = 86), and 2.18 ± 0.45 (1.23–3.03) for 80–89 years (n = 76). When we calculated the mean SUV of bilateral testes in each patient, there were significant statistical differences between those in the age group of 30–39 years and 80–89 years, 40–49 years and 80–89 years, and 50–60 years and 80–89 years, when using an unpaired test with Bonferroni correction. The laterality index (|L − R|/(L + R) × 2) in 203 men was 0.066 ± 0.067 (0–0.522). There was a mild correlation between the mean SUV and age (r = −0.284, P < 0.001) as well as between the mean SUV and mean volume (r = +0.368, P < 0.001). There was no correlation between the mean SUV and glucose blood level (r = −0.065, P = 0.358).Some uptake of FDG is observed in the normal testis and declines slightly with age. Physiological FDG uptake in the testis should not be confused with pathological accumulation.
Keywords: Testis; 18F-FDG; Physiological uptake; PET/CT
False-positive FDG-PET scan secondary to lipoid pneumonia mimicking a solid pulmonary nodule by Babak Mokhlesi; David Angulo-Zereceda; Vahid Yaghmai (pp. 411-414).
Fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) scanning is useful in evaluating suspicious lesions of the lung. Our patient was a 65-year-old woman with a 45-pack-year smoking history who was referred for further evaluation because of a 3 cm × 3 cm solid lung nodule on computed tomography scan of the chest. FDG-PET scan revealed a standard uptake value of 3.2 suggestive of malignancy. The histology of the lung nodule was consistent with lipoid pneumonia, a benign condition frequently associated with inadvertent aspiration or inhalation of oily substances.
Keywords: Lipoid pneumonia; FDG-PET scan; Lung mass
FDG-PET/CT finding of high uptake in pulmonary alveolar microlithiasis by Kimiteru Ito; Kazuo Kubota; Masashi Yukihiro; Shinyu Izumi; Shinsuke Miyano; Koichiro Kudo; Yuki Sasao (pp. 415-418).
Pulmonary alveolar microlithiasis (PAM) is a rare lung disease characterized by progressive intra-alveolar calcification. We present a case of PAM with abnormal accumulation of 18F-fluorodeoxyglucose (FDG) in both lungs. A 55-year-old man was referred to our hospital for progressive dyspnea. He had been diagnosed with PAM 25 years earlier by transbronchial lung biopsy. High-resolution computed tomography revealed multiple dense calcifications with little aerated lung. Combined positron emission tomography and computed tomography using 18F-FDG (FDG-PET/CT) showed the abnormal accumulation of FDG in both lungs with a maximal standardized uptake value of 7.3. High FDG uptake was observed mainly in the lung regions showing sparing calcification. The patient died of respiratory failure a month later and an autopsy revealed no significant inflammatory changes in either lung. We suspect that the markedly enhanced pulmonary FDG uptake may have some relation to the pathophysiology of PAM.
Keywords: Pulmonary alveolar microlithiasis; FDG; PET; CT