Shung-Shung Sun

Sex- and Age-Related Differences in Brain FDG Metabolism of Healthy Adults: An SPM Analysis

The purpose of our study was aimed to analyze the sex‐ and age‐related differences of brain metabolism in healthy individuals.

FDG PET/CT of a late-term pregnant woman with breast cancer.

A 38-year-old pregnant woman at 26-week gestation with left breast cancer requested an FDG PET/CT scan for more detailed staging of her breast cancer before treatment. After discussing the potential radiation-related risk and estimating possible absorbed dose to fetus, she consented for examination. By using a low-radiation-dose CT protocol and administration of routine 370-MBq FDG without diuresis, the resultant calculated (using existing models to predict fetal radiation exposure) fetal dose from CT and FDG would be 3.60 mGy and 6.29 mGy, respectively. In contrast to the existing few literatures, our case also demonstrated previously unreported uptake in the fetal kidneys.

Treating hepatocellular carcinoma with 90Y-bearing microspheres: a review

Hepatocellular carcinoma (HCC) is a disease usually diagnosed in its advanced-stage, and is frequently not amenable to curative surgical treatment. Also, HCC is resistant to chemotherapy and less vulnerable to radiation therapy compared to normal hepatic parenchyma. Both of these facts render the efficacy of adjuvant and palliative treatments problematic. Selective internal radiation therapy (SIRT) with 90Y-bearing microspheres is characterized by preferentially delivering substantially high doses of radiation to a liver tumor dose simultaneously limiting the damage to its non-tumorous cells, providing an opportunity for effective local tumor control and even tumor regression therapy. The current article reviews the specific characters, dosimetry, possible applications, and special considerations toward the pre-existing radiation therapy of 90Y microsphere SIRT in treating HCC.

Hepatic macronodular tuberculoma mimics liver metastasis in a patient with locoregional advanced tongue cancer

Case Report A 55-year-old man had disseminated tuberculosis involving the lungs and right foot, with initial presentation of complicated right foot cellulitis. He had undergone antituberculosis treatment with combined use of pyrazinamide, rifampin, ethambutol, and isoniazid in April 2005. Other than the persistent abnormal appearance of plain chest radiographs, there were no clinical events thereafter. However, in September 2010, the patient presented with gradual dysphagia and odynophagia. On physical examination, an enlarged and indurated mass was noted on the left hemitongue. Several enlarged, painless, and fixed lymph nodes were palpable on the left upper neck region. Laboratory studies revealed normal blood counts, liver function tests, renal function, and inflammatory biomarkers. Incisional biopsy of the tongue mass confirmed the diagnosis of squamous cell carcinoma (SCC). Contrast-enhanced computed tomography (CT) of the head/ neck, chest, and upper abdomen for pretreatment evaluation revealed locally advanced tongue cancer (Fig 1A; arrow) and lymph node metastases in the left upper neck (Fig 1B; arrowhead). In addition, patchy consolidation with cystic, calcified, and fibronodular change was noted in the left lung (Fig 1C), compatible with pulmonary tuberculosis also confirmed by the subsequent polymerase chain reaction assay for Mycobacterium tuberculosis complex from the patient’s sputum. Nevertheless, a hypodense nodule with minimal enhancement, measuring 16 12 mm, was found in segment four of the liver (Figs 2A, 2B; arrows). For further differentiation of the hepatic lesion and whole-body survey of the tongue cancer, fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed, revealing hypermetabolic lesions suggestive of malignancy in the left tongue (Fig 2C; maximum standardized uptake value [SUVmax], 13.2) and bilateral upper neck regions (Fig 2C; SUVmax, 3.2). Moreover, it also showed heterogeneous intense radioactivity (SUVmax, 2.8) in the left upper lung region (Fig 2C), compatible with an active inflammatory process such as pulmonary tuberculosis. Nevertheless, abnormal FDG uptake (SUVmax, 3.0) was also found in segment four of the liver (Figs 2C to 2E; arrowheads). Although the character of FDG uptake in the hepatic lesion might have been attributable to malignancy, an inflammatory process such as tuberculosis was also possible, because the lungs revealed probable active inflammation as with pulmonary tuberculosis. However, whether hepatic tuberculoma or hepatic metastasis from locoregional advanced tongue cancer, it was an unusual clinical manifestation. To determine a treatment strategy, it was necessary to obtain pathologic confirmation of the hepatic lesion. Histologic examination of the hepatic nodule via CT-guided biopsy revealed caseating granulomatous inflammation characteristic of hepatic tuberculoma (Fig 3; hematoxylin and eosin stain, 200). As a result, this patient then underwent surgery for the tongue cancer and neck lymph node metastases, with the resulting pathologic stage of T4aN2cM0, stage IVA. Adjuvant chemoradiotherapy was initiated postoperatively.

Mimicry of physiological urinary FDG excretion: squamous cell carcinoma of esophagus metastasizing to psoas muscle.

Skeletal muscle metastases are rare and usually occur with various malignancies at more advanced stages. FDG PET/CT has been known as a useful tool to detect these lesions because of the character of whole-body scanning and superior contrast between malignant and normal tissues, except in areas with abundant physiological FDG radioactivity, such as the urinary system. We present a patient with esophageal squamous cell carcinoma and an incidental, rare finding of psoas muscle metastasis that was initially omitted because of the similarity of its distribution to physiological urinary FDG excretion in the ureter.

Simultaneous rectal schwannoma and prostatic adenocarcinoma detected on FDG PET/CT.

A case of an 84-year-old man with suspicious rectal cancer has been reported. The patient underwent FDG PET/CT for whole-body survey. Unexpectedly, FDG PET/CT demonstrated abnormally increased FDG uptake in rectum (SUVmax: 3.33) and prostate (SUVmax: 5.66) simultaneously. Ultimately, biopsies of rectal tumor and prostatic gland confirmed diagnoses of synchronous schwannoma in the rectum and adenocarcinoma in the prostate. To our best knowledge, this is the first case of rectal schwannoma with representative FDG PET/CT scan in the literature.

Findings of cerebral metastasis demonstrated on Tc-99m TRODAT-1 SPECT.

A 71-year-old man, with a history of movement disorder presented with tremor, unstable gait, and bradykinesia for 2 years. He was referred for Tc-99m TRODAT-1 single photon emission computed tomography (Tc-99m TRODAT-1 SPECT) to detect dysfunction of the nigrostriatal system. The 3-slice composite image of the highest TRODAT-1 basal ganglia activity demonstrated markedly asymmetric tracer uptake in the bilateral striata and an unexpected oval-like uptake in the right occipital lobe. After detailed survey, it was confirmed as cerebral metastasis from colon cancer. This reminds us to pay more attention to other coincidental findings on routine examinations.

Clinically unrecognized pulmonary aspiration during gastrointestinal endoscopy with sedation: a potential pitfall interfering the performance of 18F-FDG PET for cancer screening.

PURPOSE We found several cases with unexpected pulmonary abnormalities on the 18F-FDG PET scan after the gastrointestinal endoscopy with sedation during a compact health check-up course, interfering the interpretations of 18F-FDG PET scan for cancer screening. The current studies aimed to analyze the incidence and the clinical relevance of this pulmonary finding. MATERIALS AND METHODS From June to December 2009, 127 subjects undergoing the sequential gastrointestinal endoscopy with sedation and 18F-FDG PET scan within 48 h as part of routine health check-up were retrospectively enrolled in this study. The incidence of abnormal pulmonary findings and their SUVmax of FDG were calculated and correlated with the clinical manifestations. RESULTS Five subjects had abnormal 18F-FDG PET findings but pulmonary symptoms were only found in 2. The SUVmax did not seem to reflect the severity of pulmonary symptoms or the need of intervention. Although the incidence of unrecognized pulmonary aspiration featuring inflammation detected by the 18F-FDG PET scan was high (3.94%, 5/127), the incidence of events needed intervention remained low (0.79%, 1/127), similar to those previously reported literatures. CONCLUSIONS Although higher incidence of pulmonary aspiration in this study, it probably reflects the better sensitivity of 18F-FDG PET for inflammation. The low incidence of clinical events needed intervention may still reflect the safety of sedation used for gastrointestinal endoscopy. Proper arrangement of the sequential examinations if subjects need both gastrointestinal endoscopy with sedation and 18F-FDG PET is important to reduce the interference degrading the performance of 18F-FDG PET in cancer screening, diagnosis or staging.

Findings of subdural hematoma on Tc-99m-TRODAT-1 SPECT.

Chronic subdural hematoma (SDH) is difficult to diagnose by clinical manifestations only. Nonspecific neurologic symptoms and signs may lead physicians to make other diagnoses. Although head trauma is the most common cause, it may be considered insignificant or omitted due to its minor initial manifestations. We present a patient with an incidental finding of SDH on Tc-99m-TRODAT-1 SPECT that was originally done for evaluation of his Parkinsonism. This reminds us to be vigilant about other possible coincidental findings on routine examinations.

Bilateral breast uptake demonstrated on FDG PET/CT scans in 3 male patients with hepatocellular carcinomas.

We reported 3 male patients with hepatocellular carcinoma who underwent FDG PET/CT for systemic survey before liver transplantation. All of their scans demonstrated obvious FDG uptake in bilateral breasts. These uptakes might be owing to gynecomastia caused by an increase in free estrogen related to the cirrhotic liver.