Makoto Kajihara

Incidence and characteristics of uterine leiomyomas with FDG uptake

ObjectiveUterine leiomyomas sometimes show focal 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) images that may result in a false-positive diagnosis for malignant lesions. This study was conducted to investigate the incidence and characteristics of uterine leiomyomas that showed FDG uptake.MethodsWe reviewed FDG-PET and pelvic magnetic resonance (MR) images of 477 pre-menopausal (pre-MP, age 42.1 ± 7.3 years) and 880 post-MP (age 59.9 ± 6.8 years) healthy women who underwent these tests as parts of cancer screening. Of 1357, 323 underwent annual cancer screening four times, 97 did three times, 191 did twice, and the rest were screened once. Focal FDG uptake (maximal standardized uptake value > 3.0) in the pelvis was localized and characterized on co-registered PET/MR images.ResultsUterine leiomyomas were found in 164 pre-MP and 338 post-MP women. FDG uptake was observed in 18 leiomyomas of 17 of the 164 (10.4%) pre-MP women and in 4 leiomyomas of 4 of the 338 (1.2%) post-MP women. The incidence was significantly higher in pre-MP women than in post-MP women (chi-square, P < 0.001). Of the 22, 13 showed signal intensity equal to or higher than that of the myometrium on T2-weighted MR images, which suggested abundant cellularity, whereas the majority of leiomyomas without FDG uptake showed low signal intensity. Of the 13 women, 12 examined more than twice showed substantial changes in the level of FDG uptake in leiomyomas each year with FDG uptake disappearing or newly appearing. These changes were observed frequently in relation with menopause or menstrual phases.ConclusionsLeiomyomas with focal FDG uptake were seen in both pre-and post-MP women with a higher incidence in pre-MP women. Abundant cellularity and hormonal dependency may explain a part of the mechanisms of FDG uptake in leiomyomas. It is important to know that the level of FDG uptake in leiomyomas can change and newly appearing FDG uptake does not necessarily mean malignant transformation.

Measurement of tumor blood flow using dynamic contrast-enhanced magnetic resonance imaging and deconvolution analysis : A preliminary study in musculoskeletal tumors

Objective: To measure tumor blood flow (TBF) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Methods: A DCE-MRI was performed using inversion recovery-preparation fast-field echo sequences. Dynamic data were obtained every 3.2 seconds for 2 minutes, immediately after gadolinium injection. In 14 patients with malignant musculoskeletal tumors, TBF maps were generated pixel-by-pixel by deconvolution analysis. For preclinical studies, muscle blood flow in 5 volunteers and signal intensities of different gadolinium concentrations were measured. Results: There was a good linear relationship between signal intensities and gadolinium concentrations (r = 0.989, P < 0.001, at gadolinium concentrations ≤2 mmol/L). The average value of muscle blood flow in volunteers was 11.1 ± 2.7 mL·100 mL−1·min−1. In 14 patients with musculoskeletal tumors, TBF showed wide variances: the lowest of 9.6 mL·100 mL−1·min−1 in liposarcoma and the highest of 182.0 mL·100 mL−1·min−1 in osteosarcoma. After chemotherapy, the TBF values (7.9, 11.0, and 11.7 mL· 100 mL−1·min−1) in the good responders were lower than those (26.8, 31.0, and 62.4 mL·100 mL−1·min−1) in the poor responders. Conclusions: A functional map of TBF generated by DCE-MRI and deconvolution analysis would be a promising tool for evaluating tumor blood flow in vivo.

Evaluation of tumor blood flow in musculoskeletal lesions: dynamic contrast-enhanced MR imaging and its possibility when monitoring the response to preoperative chemotherapy—work in progress

PurposeThe objective of this study was to calculate tumor blood flow (TBF) in musculoskeletal lesions and to evaluate the usefulness of this parameter in differentiating malignant from benign lesions and monitoring the treatment response to preoperative chemotherapy.Materials and methodsAltogether, 33 patients with musculoskeletal lesions underwent a total of 50 dynamic magnetic resonance imaging (MRI) examinations, including 28 on 9 patients undergoing preoperative chemotherapy. TBF was calculated using deconvolution analysis. Steepest slope (SS) was determined from the time–intensity curve during the first pass of contrast medium.ResultsTBF ranged from 2.7 to 178.6 mL/100 mL/min in benign lesions and from 15.4 to 296.3 mL/100 mL/min in malignant lesions. SS ranged from 0.5%/s to 31.8%/s for benign lesions and from 3.1%/s to 64.8%/sec for malignant lesions. TBF and SS did not differ significantly between benign and malignant lesions. Among the nine patients who underwent preoperative chemotherapy, TBF after chemotherapy was lower in good responders (11.7, 11.0, 7.9 mL/100 mL/min) (n = 3, tumor necrosis ≥90%) than in poor responders (23.4–141.5 mL/100 mL/min) (n = 6, tumor necrosis <90%).ConclusionTBF and SS cannot reliably differentiate malignant from benign lesions. However, they have potential utility in evaluating the preoperative treatment response in patients with malignant musculoskeletal tumors.

Subcutaneous fibrolipoma in the back

A 65-year-old man presented with a subcutaneous giant mass in his upper back. The tumor had a massive fatty and nonadipose component that enhanced heterogeneously on contrast-enhanced computed tomography and magnetic resonance imaging. Therefore, the lesion was initially thought to be a liposarcoma or spindle cell lipoma. After surgery, the tumor was histologically diagnosed as a fibrolipoma. Subcutaenous fibrolipoma is a rare neoplasm that is defined as a subtype of lipoma.

Thallium-201 scintigraphy in bone and soft-tissue tumors: a comparison of dynamic, early and delayed scans

Objective: It has been reported that delayed scan of thallium-201 (201Tl) scintigraphy is useful for differentiating malignant tumors from benign lesions and for evaluating treatment response. However, physiological muscle uptake which usually increases in delayed scans, often makes it difficult to evaluate201T1 uptake and its washout in bone and soft-tissue tumors. The purpose of this study was to evaluate whether the delayed scan is necessary and whether a dynamic scan is useful in the evaluation of bone and soft-tissue tumors.Methods: We studied 175 cases of bone and soft-tissue tumors (malignant 45, benign 130). Dynamic scans were acquired every 5 seconds for 10 minutes after201T1 injection, and time activity curves (TACs) were generated by adaptive smoothing methods. Early and delayed scans were acquired at 10–15 minutes and 2 hours after injection.20lTl images were visually interpreted and the radioactivity count ratio (T/N) of tumors to normal tissues and washout rate [WR = (early T/N - delayed T/N)/early T/N] were denned.Results: When there were no201T1 uptake in dynamic (n = 67) and early scans (n = 68), no tumor uptake was also appreciated in delayed scans, and all but two cases of negative scans were benign. In 107 lesions, although there were significant differences in T/Ns between malignant and benign lesions both on early scans (2.84 ± 1.45 vs. 2.05 ± 1.13, p < 0.05) and delayed scans (2.17 ± 1.03 vs. 1.58 ± 0.64, p < 0.05), there was a substantial overlap. The T/Ns decreased in delayed scans (i.e., WR > 0) in 100 of 107 cases due to increase of surrounding muscle uptake, and there was no difference in WR between malignant tumors and benign lesions (0.21 ± 0.14 vs. 0.19 ± 0.14).Conclusions: For evaluating bone and soft-tissue tumors, delayed scan had little clinical usefulness and it may be time consuming. Dynamic scan would be useful for demonstrating the differences between tumor blood flow and201Tl uptake in tumors.

Oncocytic carcinoid tumor of the lung with intense F-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography–computed tomography (PET/CT)

The present report describes a case of typical carcinoid tumor with intense fluorodeoxyglucose (FDG) uptake. The most of tumor cells were characterized by eosinophilic cytoplasm resulting from accumulation of mitochondria, which was called an oncocytic carcinoid tumor. Glucose transporter type 1 (GLUT-1) was expressed in a membranous pattern in the oncocytic component. Oncocytic carcinoid tumors could show intense FDG uptake due to the numerous intracellular mitochondria and the membranous overexpression of GLUT-1. Thus, it could be a potential pitfall of interpreting FDG-PET/CT image.

Accumulation of Tc-99m HMDP in ovarian serous papillary adenocarcinoma reflecting ongoing calcification.

In a 64-year-old woman who had ovarian serous papillary adenocarcinoma, Tc-99m HMDP bone scintigraphy showed avid accumulation in the primary tumor and its peritoneal metastases. Histologic analysis revealed psammoma bodies within the papillary growth of tumor cells. Serial computed tomographic (CT) scans showed ongoing dense calcifications corresponding to the uptake revealed by bone scintigraphy.