Takashi Hakamatsuka

Evaluation of the relationship between physiological FDG uptake in the heart and age, blood glucose level, fasting period, and hospitalization

ObjectivePositron emission tomography (PET) with fluorodeoxyglucose (FDG) is widely used for evaluation of cancer and ischemic heart disease. Recently, increased myocardial FDG uptake has been reported to be related to some types of heart disease, such as sarcoidosis. However, the physiological increased FDG uptake in the heart often mimics the abnormal high uptake in these cases. In this study, we investigated the relationships between myocardial uptake and age, blood glucose level, fasting period, and hospitalization status (inpatient vs. outpatient).MethodsA total of 159 non-diabetic patients were enrolled in the present study. Patients were imaged on a PET/CT scanner, and a three-dimensional region of interest (ROI) was drawn on the fused PET/CT image to measure the maximum standardized uptake value (SUVmax) of the whole left ventricle.Results: No significant relationships were observed between myocardial uptake and age or fasting period. Blood glucose level showed a significant relationship (p = 0.025) with myocardial uptake, but the R-square was extremely small (r2 = 0.03). With an SUVmax threshold of 3.0, there was no significant difference between inpatients and outpatients. However, outpatients showed a significantly higher frequency of myocardial uptake over SUVmax of 5.0 (x2 test: p = 0.046).ConclusionIt is difficult to predict the degree of physiological uptake in the heart from data regarding age, fasting period, or blood glucose level. Outpatients tend to show higher myocardial uptake than inpatients, which may make it difficult to detect abnormally increased uptake in the heart. A long fasting period, such as overnight fasting, is an inadequate means to reduce the physiological uptake of FDG in the heart.

Initial evaluation of dynamic human imaging using18F-FRP170 as a new PET tracer for imaging hypoxia

Abstract18F-FRP170, 1-(2-fluoro-1-[hydroxymethyl]ethoxy)methyl-2-nitroimidazole, is a new hypoxia imaging agent for positron emission tomography. This compound was synthesized by18F-labeling of RP170, which was developed as a new hydrophilic 2-nitroimidazole analog. In the present study, we analyzed dynamic whole-body imaging in healthy volunteers and dynamic tumor imaging in three patients with lung cancer.Methods: Four healthy male volunteers and three lung cancer patients were enrolled in this study. Volunteers underwent dynamic whole-body scans just after injection of18F-FRP170 for about 90 min, while the lung cancer patients underwent dynamic tumor imaging for about 60 or 120 min. Data are expressed as standardized uptake values (SUV). Regions of interest were placed over images of each organ or tumor to generate time-SUV curves.Results: The series of dynamic whole-body scans showed rapid elimination of18F-FRP170 from the kidneys following elimination from the liver. Very low physiological uptake was observed above the diaphragm.18F-FRP170 uptake in the lung cancer lesion could be visualized clearly from early after injection. The changes of tumor SUV, tumor/blood ratio, or tumor/muscle ratio about 30 min after injection or later were small.Conclusions: Dynamic imaging using18F-FRP170 demonstrated rapid elimination from the kidney, suggesting the high hydrophilicity of this imaging agent. The background activity above the diaphragm was very low, and patients with lung cancer showed clear tumor uptake of18F-FRP170 early after injection.

FDG PET in solitary metastastic/secondary tumor of the kidney: a report of three cases and a review of the relevant literature

Metastatic tumors or secondary lymphoma of the kidney are rare and can often be missed on conventional computed tomography (CT) imaging. On the other hand, many types of metastatic tumor or lymphoma can be detected clearly as hotspots of elevated uptake on FDG PET. However, excreted FDG present in the urinary tract mimics these findings and interferes with image reading. Careful investigation of the renal cortex by FDG PET and review of anatomical images, such as the findings of CT and MRI, have important roles in the detection of renal tumor. Here, we present three cases of solitary metastatic/secondary tumor of the kidney, and discuss the features of the lesions on FDG PET in comparison with their appearance on CT.

Scatter and cross-talk correction for one-day acquisition of123i-bmipp and99mtc-tetrofosmin myocardial spect

Objective:123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and99mTc-tetrofosmin (TET) are widely used for evaluation of myocardial fatty acid metabolism and perfusion, respectively. ECG-gated TET SPECT is also used for evaluation of myocardial wall motion. These tests are often performed on the same day to minimize both the time required and inconvenience to patients and medical staff. However, as123I and99mTc have similar emission energies (159 keV and 140 keV, respectively), it is necessary to consider not only scattered photons, but also primary photons of each radionuclide detected in the wrong window (cross-talk). In this study, we developed and evaluated the effectiveness of a new scatter and cross-talk correction imaging protocol.Methods: Fourteen patients with ischemic heart disease or heart failure (8 men and 6 women with a mean age of 69.4 yr, ranging from 45 to 94 yr) were enrolled in this study. In the routine one-day acquisition protocol, BMIPP SPECT was performed in the morning, with TET SPECT performed 4 h later. An additional SPECT was performed just before injection of TET with the energy window for99mTc. These data correspond to the scatter and cross-talk factor of the next TET SPECT. The correction was performed by subtraction of the scatter and cross-talk factor from TET SPECT. Data are presented as means ± S.E. Statistical analyses were performed using Wilcoxon’s matched-pairs signed-ranks test, and p < 0.05 was considered significant.Results: The percentage of scatter and cross-talk relative to the corrected total count was 26.0±5.3%. EDV and ESV after correction were significantly greater than those before correction (p = 0.019 and 0.016, respectively). After correction, EF was smaller than that before correction, but the difference was not significant. Perfusion scores (17 segments per heart) were significantly lower after as compared with those before correction (p < 0.001).Conclusions: Scatter and cross-talk correction revealed significant differences in EDV, ESV, and perfusion scores. These observations indicate that scatter and cross-talk correction is required for one-day acquisition of123I-BMIPP and99mTc-tetrofosmin SPECT.

Current abstracts of the articles published in The Japanese Journal of Nuclear Medicine

Sympathetic nerve system is activated as a compensatory mechanism in heart failure. However, excessive activation of sympathetic nerve system deteriorates disease state. Sympathetic nerve system can be suppressed with N-type Ca 2+ channel blocker. An antihypertensive drug, cilnidipine, is a dual L/N-type Ca 2+ channel blocker. We studies usefulness of cilnidipine in treating with chronic heart failure with 123I-MIBG myocardial scintigraphy. We enrolled 24 patients with stable chronic heart failure. Twelve patients were treated with ACE-inhibitors, diuretics and cardiotonics (control group), and the other 12 patients were treated with ACE-inhibitors, diuretics, cardiotonics and cilnidipine (cilnidipine group). We examined blood pressure, heart rate, norepinephrine level, brain natriuretic peptide (BNP) level, cardiothoracic ratio on chest X-ray, ejection fraction of left ventricle on two-dimensional echocardiography, count rate of heart to mediastinum (H/M) and washout rate (WOR) on 123I-MIBG myocardial scintigraphy before and six months after medication. Symptom was improved in 8 patients in the control group and 10 patients in the cilnidipine group after medication. And another parameters were also improved in the both groups after medication. However the degree of change in blood pressure (mmHg) was 21.2 _+ 8.0 in the cilnidipine group and 10.8 _+ 9.1 in the control group, that in heart rate (/min) was 24.1 +_ 6.8 and 16.2 _ 11.0, that in BNP level (pg/m/) was 65.2 _ 12.0 and 42.8 _ 11.1, that in H/M was 0.30 _ 0.08 and 0.19 _+ 0.09, that in WOR was 19.4 _ 5.6 and 12.2 _ 7.0, respectively. And the degree of these changes were larger in the cilnidipine group (p < 0.05). These findings suggested that cilnidipine, a dual L/N-type Ca 2+ channel blocker, might be useful in treating with chronic heart failure.

Usefulness of asialoglycoprotein receptor imaging for the evaluation of liver metastasis of neuroblastoma

Neuroblastoma, derived from the neural crest ectoderm, is the most common type of solid abdominal mass seen in infancy. The diagnosis, staging, and follow-up of neuroblastoma are often performed using metaiodobenzylguanidine (MIBG) imaging. However, the evaluation of liver metastasis by this method is complicated by the normal physiological uptake of MIBG by the liver. The asialoglycoprotein receptor is a hepatic cell-surface receptor specific for galactose-terminated glycoprotein, and99mTc-DTPA-galactosyl human serum albumin (GSA) accumulates selectively in hepatic cells. Here, we report a case of congenital neuroblastoma with liver metastasis in which GSA scans were useful for differentiation between normal and metastatic sites in the liver.