Kiyoko Kusakabe

Comparison of Imaging Protocols for 18F-FDG PET/CT in Overweight Patients: Optimizing Scan Duration Versus Administered Dose

The quality of 18F-FDG PET/CT images of overweight patients is often degraded. We evaluated the effect of optimizing injected dose or acquisition time on the quality of images of overweight patients using lutetium oxyorthosilicate PET/CT with high-performance detector electronics. Methods: We initially retrospectively measured radioactivity concentrations and signal-to-noise ratios (SNRs) in the liver relative to body weight for 80 patients who had undergone 18F-FDG PET/CT according to our standard protocol (injected dose, 3.7 MBq/kg; acquisition time, 2 min/bed position). The patients were grouped (n = 20 per group) according to baseline body weight as G1 (≤59 kg), G2 (60–69 kg), G3 (70–84 kg), and G4 (≥85 kg). We compared the SNRs of G1 with those of G2, G3, and G4 and calculated the ratio squared as a factor to correct the acquisition parameters for overweight patients. We then prospectively enrolled 120 patients according to the same body weight criteria. We multiplied the correction factors to optimize injected doses or acquisition times and defined dose-adjusted groups (n = 20 per group) and time-adjusted groups (n = 20 per group). G2 dose was defined as 5.59 ± 0.19 MBq/kg, G3 dose as 7.29 ± 0.33 MBq/kg, and G4 dose as 8.88 ± 0.43 MBq/kg. G2 time was defined as 3 min/bed position, G3 time as 4 min/bed position, and G4 time as 5 min/bed position. Results: Although liver activities did not significantly differ among G1 through G4 irrespective of patient weight, SNR progressively decreased as patient weight increased. The liver activities of G2 dose, G3 dose, and G4 dose were, respectively, 1.4-, 1.9-, and 2.5-fold higher than those of the baseline counterparts. Nevertheless, the increased liver activities of G2 dose, G3 dose, and G4 dose did not significantly affect SNR, compared with the baseline groups. In contrast, the SNR of G4 time was significantly higher than that of G4. Conclusion: Our findings suggest that the quality of images acquired from heavier patients can be maintained only by scanning for longer periods. Increasing the dose per kilogram of body weight did not improve the quality of lutetium oxyorthosilicate PET/CT images.

Surgical strategy for pheochromocytoma: Emphasis on the pledge of flank extraperitoneal approach in selected patients

BACKGROUND Anterior transabdominal exploration has traditionally been advocated as the standard procedure for pheochromocytoma. However, some authors claim that a flank extraperitoneal approach with accurate unilateral localization is justifiable. METHODS Retrospective analysis was performed on 87 patients with pheochromocytoma to determine the appropriateness of extraperitoneal exploration. RESULTS There were 45 men and 42 women with a mean age of 44.7 years (range, 16 to 83 years). Fifteen patients (17.5%) had pheochromocytoma as a part of multiple endocrine neoplasia (MEN) type 2A, and four had familial pheochromocytoma, von Hippel-Lindau disease, or von Recklinghausens disease. All tumors detected by preoperative localization studies were correctly identified and were resected through flank extraperitoneal (45 patients), transabdominal (28), thoracoabdominal (13), and posterior (1) approaches. Tumors were extraadrenal in 14, multiple in 22, bilateral in 12, and unequivocally malignant in 2 patients at the initial operation. Two patients died during the immediate postoperative period, giving an operative mortality of 2.3%. Two patients had persistent disease. During follow-up within a mean period of 5 years (range, 1 month to 13.7 years) 8 patients (9.1%) experienced recurrence or metastasis. Other than the patients with MEN 2, recurrence was not attributable to the operative approach. CONCLUSIONS If a preoperative localization study is accurate, an extraperitoneal approach is justifiable for many patients with pheochromocytomas.

Primary adrenocortical micronodular dysplasia : enzyme histochemical and ultrastructural studies of two cases with a review of the literature

The adrenal glands from two patients with primary adrenocortical micronodular dysplasia (PAMD) were studied (no. 1, a 23-year-old man with cardiac myxomas and sarcoidosis; no. 2, a 16-year-old girl). The PAMD cells showed intense activity of 3 beta-hydroxysteroid dehydrogenase (3 beta DH), succinate DH, glucose-6-phosphate DH, alkaline phosphatase (AlPase), and other DHs and lysosomal hydrolases, giving a characteristic staining pattern. The staining patterns correlated well with ultrastructural findings. The larger adrenals (no. 1: 16.6 g) were associated with larger black nodules and internodular cortex (INC) with fairly well-retained enzyme activities, and contained cell clusters and single cells with intense AlPase activity with the appearance of PAMD nodules in the buds. The smaller adrenals (no. 2: 5.4 g) were associated with smaller black/yellow nodules, and had INC with weaker enzyme activity. Analysis of descriptions of INC in 25 previously reported cases revealed that the larger adrenals (more than 10 g) had less atrophic INC than the smaller ones. The characteristic enzyme pattern in PAMD cells explains the paradox that PAMD adrenals smaller than normal can cause Cushings syndrome, and may be useful for investigating neoplastic and non-neoplastic counterparts in other adrenal lesions. The relationship between PAMD cells and INC is not simply one of autonomy versus atrophy, and both cell types may be stimulated by a certain common trophic factor. Thus, PAMD belongs to the category of hyperplasia.

Huge Thyroid Uptake of 18F-FDG in a Patient with Hashimoto's Thyroiditis Referred for a Malignant Thyroid Lesion

A combined, whole-body 2-[ F]fluoro-2-deoxy-glucose positron emission tomography (FDG-PET)=computed tomography (CT) scan was performed on a 70-year-old woman 3 years after undergoing surgery for uterine cancer. The scan revealed poor FDG uptake in the region of the primary tumor, but diffuse FDG uptake by the thyroid (Fig. 1). She was referred to our clinic for evaluation of thyroid malignancy. The patient was euthyroid and was not receiving replacement therapy (free thyroxine 0.82 ng=dL, thyrotropin 2.88 mU=mL). Her antithyroglobulin antigen level was 120 ng=mL and thyroglobulin antibody was at 8.4U=mL. Thyroid ultrasonography showed diffuse goiter (right lobe 114 45 33mm, left lobe 72 35 29mm) with typical findings for Hashimoto’s thyroiditis (Fig. 2). Ultrasound-guided fine-needle aspiration cytology was negative for malignant cells, but positive for small lymphocytes with follicular cells. As FDG-PET scans became popular for management of malignant conditions in various organ systems, the number of cases of incidental thyroid uptake without malignant disorder’s has increased. Such uptake has been reported for patients with Hashimoto’s thyroiditis, Graves’ disease, and adenomatous nodules. The prevalence of malignancy in incidental thyroid uptake has been reported to be 18% to 50% (1,2). In cases of diffuse or bilateral thyroid uptake, the possibility of malignant lesions is estimated to be lower. Since proliferating lymphocytes in chronic tonsillitis can uptake FDG (3), thyroidal lymphocytes in Hashimoto’s thyroiditis may also uptake FDG like malignant cells under certain conditions. Therefore, thyroidologists involved in diagnosing such disorders by PET scan should be aware of the possibility of incidental thyroid uptake and should make diagnoses in combination with other methods such as ultrasonography.

Is subendocardial or transmural late gadolinium enhancement able to differentiate between dcm and icm on cardiac mri

Introduction In ischemic cardiomyopathy (ICM), subendocardial and transmural late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) are useful findings to differentiate from dilated cardiomyopathy (DCM). The previous studies emphasize that all ICM shows subendocardial or transmural LGE based on fibrosis of infracted myocardium, however ICM with no LGE such as hibernated myocardium caused low EF and LV dilatation as well as DCM also exists.