Katsuya Sugimoto

Evaluation of62Cu labeled diacetyl-bis(N 4-methylthiosemicarbazone) as a hypoxic tissue tracer in patients with lung cancer

Abstract62Cu labeled diacetyl-bis(N4-methylthiosemicarbazone) (62Cu-ATSM) has been proposed as a generator-produced, positron-emitting tracer for hypoxic tissue imaging. From basic studies, the retention mechanism of62Cu-ATSM is considered to be closely related to cytosolic/microsomal bioreduction, a possible system for hypoxic bioreductive drug activation. In order to evaluate the characteristics of62Cu-ATSM, PET studies were performed in 4 normal subjects and 6 patients with lung cancer.62Cu-ATSM cleared rapidly from the blood with little lung uptake (0.43±0.09, uptake ratio; divided by the arterial input function) in normal subjects. Intense tumor uptake of62Cu-ATSM was observed in all patients with lung cancer (3.00±1.50). A negative correlation was observed between blood flow and flow-normalized62Cu-ATSM uptake in three of four patients. In contrast,62Cu-ATSM uptake was not related to that of18F-fluorodeoxyglucose. The negative correlation between blood flow and flow normalized62Cu-ATSM uptake suggests an enhancement of retention of62Cu-ATSM by low flow.62Cu-ATSM is a promising PET tracer for tumor imaging, which might bring new information for chemotherapeutic treatment as well as radiotherapy of hypoxic tumors.

Copper-62 ATSM as a hypoxic tissue tracer in myocardial ischemia

Copper-62 labeled diacetyl-bis (N4-methylthiosemicarbazone) (62Cu-ATSM) has been proposed as a generator produced positron-emitting tracer for hypoxic tissue imaging. To clarify the usefulness of62Cu-ATSM for myocardial ischemia,62Cu-ATSM PET was performed in 7 patients with coronary artery disease. Increased myocardial uptake of62Cu-ATSM was observed (myocardium/blood ratio: 3.09) in one patient with unstable angina, who had increased18F-fluorodeoxyglucose (18F-FDG) uptake under the fasting condition. The other 6 patients, who were clinically stable, did not have increased62Cu-ATSM uptake, although abnormal18F-FDG uptake was seen in 4 patients. This preliminary study suggests that62Cu-ATSM is a promising PET tracer for hypoxic imaging in acute ischemia.

Sacral insufficiency fracture detected by FDG-PET/CT: report of 2 cases.

We report 2 cases of sacral insufficient fracture detected by FDG-PET/CT. In case 1, a 79-year-old female patient with malignant lymphoma, who had recent lumbago, received FDG-PET/CT examination. Vertical linear FDG uptake medial to bilateral sacro-iliac joint was observed on FDG-PET and a fracture line corresponding to FDG uptake was observed in bone window of CT images. In case 2, an 81-year-old male patient with colon cancer, who also complained of lumbago, received FDG-PET/CT examination. Vertical linear FDG uptake medial to bilateral sacro-iliac joint and horizontal uptake which connects vertical line (H-shaped) was demonstrated and CT also demonstrated a fracture line corresponding to FDG uptake. H-shaped high intensity area corresponding to FDG uptake was observed on T2-weighted image of MRI. On bone scintigraphy, H-shaped uptake was also observed. Like bone scintigraphy, typical H-shaped FDG uptake may be diagnostic in sacral insufficiency fracture. Adding CT information to FDG-PET, that is, assessing SIF with FDG-PET/CT may be useful when atypical findings are observed.

Technegas ventilation SPECT for evaluating silicosis in comparison with computed tomography

To compare the subtle pulmonary parenchymal morphologic changes with ventilation function in patients with silicosis, the conventional CT, high resolution CT and technegas ventilation SPECT were performed. In 25 silicotic patients and six controls, the pulmonary ventilation state was evaluated by an index called the coefficient of variation (CV), which expresses the subliminal heterogeneous distribution of technegas in the lungs. The results showed that with silicosis the CV value is significantly higher than that without silicosis. The CV value was proved by multifactorial analysis to independently reflect the extent of the appearance of small scattered interstitial findings such as nodules, septal thickening and bulla, which were typical findings for silicosis. The CV value calculated from the technegas SPECT correlated well with the severity of silicosis. It is considered that the CV value can also express the functional state of the silicotic lung.

Pathophysiological decrease in the regional cerebral blood flow in Hashimoto's encephalopathy : a multiple-case SPECT study

Background: The aim of this study was to evaluate the changes in regional cerebral blood flow (rCBF) in multiple cases of Hashimotos encephalopathy (HE). Methods: Seven untreated patients with HE and 10 age-matched healthy controls underwent brain single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine. All patients had anti-NH2-terminal of α-enolase autoantibodies (Abs), which served as a useful diagnostic marker for HE, in addition to anti-thyroid Abs in their sera and responded to corticosteroid therapy. The obtained SPECT images were compared between the patients and the controls using 3D-SSP analysis. Results: The rCBF of all patients with HE was significantly decreased in the bilateral anterior cingulate areas and left prefrontal cortex compared with the controls (p < 0.05). Focusing on the HE patients with acute neuropsychiatric symptoms (n = 5) such as consciousness disturbance and/or psychosis, the decreased rCBF in these areas was more significant, and the rCBF in the right frontal cortex was also decreased. Conclusion: Statistical analysis of these multiple-case SPECT images revealed the regions of decreased CBF associated with clinical symptoms, especially acute neuropsychiatric symptoms, in HE patients. This study shed light on the pathophysiological decrease in rCBF observed in HE.

Myocardial FDG-PET examination during fasting and glucose loading states by means of a one-day protocol

We propose a new method to measure the myocardial FDG uptake during fasting and glucose loading in one day, a myocardial FDG-PET one-day protocol, with both 2- and 3-dimensional data acquisition (2D and 3D) without background activity subtraction. To confirm it, we evaluated the effect of scatter correction in the 2D and 3D modes of a PET scanner both in phantom and patient studies. In the phantom study, we used a cardiac phantom with six divided chambers and two cylindrical phantoms placed as the activity outside the field of view. Each chamber was filled with a different concentration of F-18 solution. Regions of interest (ROI) were placed on a polar map generated from reconstructed images and were compared to the concentration of the solution in each chamber in both 2D and 3D. In the patient study, 10 non-diabetic patients with coronary artery disease were studied. Each patient received a myocardial FDG study during fasting (F) and glucose loading (L). L images with background subtraction (Lsub(+)) and without background subtraction (Lsub(−)) were compared by polar map analysis. The ROI counts for the true activity in 2D and 3D demonstrated a linear relationship, and quite similar slopes were observed (0.72 in 2D, 0.69 in 3D). The background fraction in Lsub(−) was 3.59±1.83%. There were significant differences between Lsub(−) or Lsub(+), and F in both normal and ischemic myocardium. Scatter correction was successfully performed in both 2D and 3D modes. Background activity is thought to be negligible and this proposed method is simple touse in measuring the myocardial FDG uptake in one day.

A trial for the quantification of regional myocardial blood flow with continuous infusion of Tc-99m MIBI and dynamic SPECT

We propose a new method to quantify regional myocardial blood flow (rMBF) by continuous infusion of Tc-99m MIBI and dynamic SPECT.MethodsFive patients with old myocardial infarction were studied. During continuous infusion of MIBI (approximately 740 MBq) with a syringe pump in 10 min, dynamic SPECT scan was performed every minute and lasted 20 min after the start of infusion to identify myocardial uptake of MIBI. Input function was obtained from the radioactivity in the left ventricle (LV) in dynamic SPECT images. Spillover fraction between LV and myocardium (M) was corrected with phantom data. The influx constant (Ku) was calculated by Patlak plot graphical analysis, and compared with rMBF measured by PET (F) with N-13 ammonia based on Patlak plot analysis with correction for the extraction fraction. To correct the limited first-pass extraction of MIBI, linearization correction by means of the permeability-surface area (PS) product value was also applied. Results: Spillover fractions of MIBI were 0.169 ± 0.056 from LV to M, and 0.042 ± 0.021 from M to LV. Ku was well correlated with F (Ku = 0.057 + 0.220F, r = 0.83, p < 0.01) and the slope and correlation were improved after linearizaiton (Fmibi = −0.131+ 0.858F, r = 0.94, p < 0.01). Conclusion: The proposed method has the potential to be a clinically feasible tool for quantitative measurement of rMBF.

Arterial spin labeling MR imaging for the clinical detection of cerebellar hypoperfusion in patients with spinocerebellar degeneration

PURPOSE The aim of this study was to evaluate the clinical utility of arterial spin labeling (ASL) magnetic resonance imaging (MRI) for the detection of cerebellar hypoperfusion in patients with spinocerebellar degeneration (SCD). METHODS Regional cerebral blood flow (CBF) were obtained from ASL and 123I-IMP single-photon emission computed tomography (SPECT) images by volume-of-interest analysis in patients with SCD (n = 16). Regional CBF were also measured by ASL in age-matched controls (n = 19) and by SPECT in separate controls (n = 17). The cerebellar CBF values were normalized to the CBF values for the whole gray matter (nCBF) in ASL and SPECT. RESULTS The mean cerebellar nCBF measured by ASL was lower in patients with SCD (0.70 ± 0.09) than in the controls (0.91 ± 0.05) (p < 0.001), which was consistent with the comparison using SPECT (0.82 ± 0.05 vs. 0.98 ± 0.05, p < 0.001). The cerebellar nCBF measured by ASL significantly correlated with that determined by SPECT in patients (r = 0.56, p < 0.001). CONCLUSIONS ASL imaging showed decreased cerebellar blood flow, which correlated with that measured by SPECT, in patients with SCD. These findings suggest the clinical utility of noninvasive MRI with ASL for detecting cerebellar hypoperfusion in addition to atrophy, which would aid the diagnosis of SCD.

[Development of simple processing for deleting undershooting artifact using the FBP method ─evaluation of simulation data─].

The undershooting artifact occurs using the filtered back projection (FBP) method. This artifact is influenced by a ramp filter. Thereby, the fall of the target accumulation and a deficit arise and it becomes a clinical problem. We developed a new image reconstruction method based on the FBP method to delete the undershooting artifact of FBP. The image quality of the FBP method is equivalent to that obtained by an evaluation using a digital phantom. The two segmentation and ordinary FBP methods were evaluated in terms of hot contrast, cold contrast, coefficient of variation (%CV), and root mean square uncertainty (%RSMU). The two segmentation FBP method showed equivalent values of hot contrast, % CV, and% RSMU compared with those of the ordinary FBP method. With a threshold level value, cold contrast sharply changed. However, when the threshold level of the two segmentation FBP method was set as the proper value, 90% contrast was obtained. It is necessary to set a threshold level as a proper value using the two segmentation FBP methods. I thought that it can delete an artifact in a simple way, without impairing the image quality. However, it is an examination of only a digital phantom this time. Before using it clinically, one has to use and verify a real phantom.

Quantitative assessment of truncal FDG-PET examination with postinjection transmission scan —comparison with preinjection transmission scan—

The purpose of this study was to assess the quantitative accuracy of truncal FDG PET with a postinjection transmission scan.MethodsTen subjects with lung cancer were recruited for this study. Prior to the emission scan, a transmission scan was performed for 10 min. All subjects received 370 MBq of intravenous administration of FDG prior to a 60-min emission scan. Immediately following the emission scan, a postinjection transmission scan was performed. Emission data from 40 to 60 min postinjection were reconstructed with either pre- or postinjection transmission data and converted to a standardized uptake value (SUV) image. On each SUV image, 5 regions of interest were placed and regions of interest on the SUV image with a postinjection transmission scan (SUVpost) were plotted against those with preinjection transmission (SUVpre), and a regression line was generated. Using the slope and Y-intercept of the regression line, percent error of estimation of the SUV was calculated based on the following equation: % error = ISUVpre- SUVpostl x 100/SUVpre.ResultsIn the low SUV area (SUV = 1), the averaged percent error was 9.4 ± 12.0% (mean ± SD), whereas in the high SUV area (SUV = 10), the averaged percent error was 2.8 ± 3.1%. The least percent error was 1.8 ± 1:8% (SUV = 3.8) in this study.ConclusionIn the study on truncal FDG PET with postinjection transmisson scan, the quantitative accuracy was preserved and the method is clinically available.