Asymmetric (99m)Tc-MDP uptake in mineralized tendons might mimic bone lesions: heterotopic tendon mineralization on a (99m)Tc-MDP bone scan and a (18)F-FDG PET/CT scan.

A 55-year-old man was a hepatocellular carcinoma patient, diagnosed by sonography and a biopsy. Because of his musculoskeletal tenderness, a bone scan was performed to exclude skeletal metastasis. A subsequent F-FDG PET/CT scan revealed that the unilateral abnormal uptake seen on the bone scan was actually a mineralized tendon. A mineralized tendon is easily detectable using Tc-MDP; therefore, it is imperative to differentiate between bone lesions and mineralized tendons. In addition, few studies have reported F-FDG uptake in a calcified tendon.

Huge primary soft tissue sarcoma of the breast on bone scan.

A 54-year-old woman had a primary breast sarcoma with rapid enlargement in 3 months. The mass became so huge that it was more than 20 cm in diameter and occupied the entire right breast on presentation. Extraosseous uptake was present in this mass and demonstrated a unique picture, mimicking the posture of a racing driver who holds a helmet under the armpit, on the bone scan.

Clinical impact of 18F-FDG-PET in the suspicion of recurrent colorectal cancer based on asymptomatically elevated serum level of carcinoembryonic antigen (CEA) in Taiwan.

BACKGROUND/AIMS: To retrospectively evaluate the impact of 18F-fluorodeoxy-glucose-positron emission tomography (FDG-PET) to detect recurrent colorectal cancer based on asymptomatically elevated tumor marker level of carcinoembryonic antigen (CEA). METHODOLOGY: Whole-body FDG-PET was performed in 50 patients suspected of having recurrent colorectal cancer and asymptomatically increased serum level of CEA (> 5 ng/mL), but other negative or equivocal imaging modality results. A blood sample was drawn in each case for CEA assay on the same day as the FDG-PET. The final diagnosis of recurrent colorectal cancer was established by operation/biopsy histopathological findings or clinical follow-up longer than 1 year by additional morphologic imaging techniques. RESULTS: Among the 50 patients, the final diagnosis of recurrent colorectal cancer was established in 64 lesions of 45 patients. FDG-PET could accurately detect 62 lesions but missed 2 false-negative lesions. In addition, there were 2 false-positive lesions. On a lesion-based analysis, the diagnostic sensitivity and positive predictive value of FDG-PET was 96.9%. There were 2 patients with false-negative lesions and 2 patients with false-positive lesions. Therefore, FDG-PET findings could lead to successful surgical resection in 41 (82.0%) patients. In addition, on a patient-based analysis, the diagnostic sensitivity and positive predictive value of FDG-PET was 95.3%. CONCLUSIONS: FDG-PET is a useful technique for detecting recurrent colorectal cancer suspected by asymptomatically elevated serum level of CEA and has an important clinical impact on the management in patients with suspected recurrent colorectal cancer.

Clinical usefulness of fused PET/CT compared with PET alone or CT alone in nasopharyngeal carcinoma patients.

UNLABELLED: The diagnostic accuracy of fused positron emission tomography/computed tomography (PET/CT) was compared with CT alone and PET alone in the staging and re-staging of nasopharyngeal carcinoma (NPC) patients. PATIENTS AND METHODS: Eighty-six fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG) PET/CT studies were retrospectively performed in 70 patients with NPC, 20 patients for primary tumor staging and 50 patients for re-staging after treatment. Each lesion was analyzed visually and assigned a score on a 5-point scale. Each study was interpreted in 3 ways: PET images were evaluated in the absence of CT data, CT images in the absence of PET data and fused PET/CT images. The results of these images were correlated with histological findings, as well as long-term radiological and clinical follow-up (the shortest follow-up period after imaging was 6 months). PET, CT and PET/CT accuracy were compared by a McNemar test. RESULTS: Fused PET/CT correctly characterized the tumor-node-metastasis system stage in 82 out of 86 studies (95.4%; 95% CI: 90.9% to 99.9%). PET alone and CT alone were found to be accurate in 71 out of 86 studies (82.6%; 95% CI: 74.5% to 90.6%) and 63 out of 86 studies (73.3%; 95% CI: 63.9% to 82.6%), respectively. Furthermore, the differences between PET/CT and either PET alone or CT alone were statistically significant (p<0.05). Overall, the study-based analysis of PET/CT for staging NPC demonstrated 48 true-positive, 2 false-negative, 34 true-negative and 2 false-positive studies. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of FDG-PET/CT studies for staging NPC were 96%, 94.4%, 95.4%, 96% and 94.4%, respectively. CONCLUSION: PET/CT is more accurate than PET alone or CT alone for the depiction of NPC. Fused PET/CT is a valuable imaging tool in patients for staging diagnosis of NPC.

Utility of FDG-PET for investigating unexplained serum AFP elevation in patients with suspected hepatocellular carcinoma recurrence.

UNLABELLED: The aim of this study was to evaluate the potential role of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in patients with unexplained rising serum alpha-fetoprotein (AFP) levels after the treatment of hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Thirty-one FDG-PET studies were performed in 26 patients (age range, 45-83; 21 men and 5 women), who had undergone either surgical resection or interventional therapy for HCC, but were subsequently noted to have high AFP serum levels on routine follow-up examinations, although imaging studies and physical examinations were normal. The FDG-PET results were correlated with histological findings, as well as long-term radiological and clinical follow-up (shortest follow-up period after FDG-PET was 6 months). RESULTS: FDG-PET was abnormal in 22 of the 31 studies (71.0%) among the 26 patients. Intrahepatic lesions were detected in 20 of a total 30 lesions (66.7%) in 18 studies of FDG-PET among 26 patients. Ten FDG-PET studies among 9 patients identified one intrahepatic lesion, while 3 studies among 3 patients identified more than one intrahepatic lesion. Extrahepatic metastases were found in 9/31 studies of FDG-PET (29.0%) among 8 patients. These metastatic foci, composed of increased FDG accumulation, were identified in several locations; lung (4 studies among 4 patients), bone (2 studies among 2 patients) and the peritoneum (4 studies among 3 patients). Overall, FDG-PET for detecting HCC recurrence demonstrated 22 true-positives, 8 false-negatives, 1 true-negative and 0 false-positive results., The sensitivity, specificity and accuracy of FDG-PET for detecting HCC recurrence was 73.3%, 100% and 74.2%, respectively. CONCLUSION: When conventional examinations are normal, FDG-PET is a valuable imaging tool in patients who have rising AFP levels after HCC treatment. FDG-PET whole-body scan also provides an important and valuable imaging study for detecting extrahepatic metastasis.

Prevalence and risk of cancer of focal thyroid incidentaloma identified by 18F-fluorodeoxyglucose positron emission tomography for cancer screening in healthy subjects.

The aim of this study was to define the clinical prevalence and rate of malignancy of focal thyroid incidentaloma in a relatively large number of individuals with application of 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) in asymptomatic individuals. The subjects consisted of 4803 physical check-up examinees (2638 men, 2165 women; mean age+/-SD, 52.8+/-9 years old) with non-specific medical history. Whole-body FDG PET was performed on all patients. Focal hypermetabolic areas of thyroid, with an intensity equal to or exceeding the level of FDG uptake in the liver, were considered abnormal and interpreted as thyroid incidentaloma. Among the 4803 FDG PET examinations, thyroid incidentaloma was present in 60 examinations, among which, 50 had further examination with ultrasound-guided fine-needle aspiration (FNA), revealing 43 benign lesions and 7 papillary carcinomas. Of 7 examinees diagnosed with cancer, 2 had lymph nodes metastasis. The mean and standard deviation of standard uptake value (SUV) in benign and carcinoma was 2.6+/-1.01 and 6.7+/-3.66, respectively. Thyroid incidentaloma identified by FDG-PET occurred with a frequency of 1.2% (60/4803). Of the thyroid incidentalomas that underwent FNA and surgery, 14% (7/50) were found to be malignant. It is possible to differentiate benign from carcinoma of thyroid incidentalomas by the increased rate of glycolysis (SUV) in the carcinoma. The small size and moderate FDG uptake of thyroid incidentalomas per se cannot guarantee low risk in incidentally found thyroid cancers.

Acute bilateral basal ganglia lesions in patients with diabetic uremia: an FDG-PET study.

PURPOSE: Head CT and MRI show characteristic changes in the syndrome of acute bilateral basal ganglia lesions in patients with diabetic uremia. However, they do not provide further insight into the underlying pathophysiology. To further clarify the biologic mechanism of the syndrome, F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) was used in 2 patients. METHODS: PET studies were performed in 2 diabetic uremic patients with acute movement disorders. The cerebral glucose metabolic rates in these 2 patients were compared with 11 normal age-matched controls. The images were further analyzed with statistical parametric mapping to identify regions of significant metabolic abnormality. RESULTS: The cases showed markedly reduced glucose metabolism in the bilateral basal ganglia, especially in the bilateral putamens, where the glucose uptake was nearly absent. CONCLUSIONS: FDG-PET correlates better with the clinical conditions and provides more pathophysiological information than head CT or MRI scans in bilateral basal ganglia lesions in patients with diabetic uremia. We propose that acute exacerbation of a long-term glucose utilization failure in the basal ganglia cells produced these lesions.

Elevated 18F-FDG uptake in skeletal muscles and thymus: a clue for the diagnosis of Graves' disease.

AIM: The aim of this study was to evaluate the appearance of Graves' disease in whole-body 2-[18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) imaging. SUBJECTS: Twenty patients (three men, 17 women; mean age +/- SD, 37.2 +/- 12.1 years) with newly diagnosed Graves' disease without anti-thyroid drug treatment took part in the study. Secondly, a control group, 15 examinees (three men, 12 women; mean age +/- SD, 45.3 +/- 13 years) each with a history of Graves' disease and post-medical treatment were recruited. This group showed normal thyroid function. Finally, a normal group, 32 physical check-up examinees with non-specific medical histories and normal thyroid functions, were recruited. Whole-body FDG PET was performed on all subjects. The intensity of FDG uptake in the thyroid, thymus and muscles region was graded subjectively on a five-point scale. RESULTS: Among the 20 patients with Graves' disease, only six (30%) showed thyroid uptake of FDG, 15 (75%) showed thymus uptake of FDG, and up to 19 (95%) showed symmetrical increased uptake of FDG in skeletal muscles. In particular, the skeletal muscle uptake of FDG in the psoas and rectus abdominis muscles was 19/20 (95%) and 12/20 (60%), respectively. In the control group, three of the 15 examinees showed thyroid uptake of FDG. In the normal group, four of the 32 examinees had faintly visualized thyroid uptake of FDG. In thymus and skeletal muscles, there was no substantially increased FDG uptake in control and normal group examinees. CONCLUSIONS: In patients with Graves' disease, the thyroid uptake of FDG is not uniformly increased. Symmetrically increased uptake of FDG in the skeletal muscles and thymus is a clue for the diagnosis of Graves' disease. The uptake of FDG in skeletal muscles is more specific in the psoas and rectus abdominis muscles. An increment of muscle FDG uptake may be responsible for the high peripheral glucose utilization seen in Graves' disease.

Application of PET and PEt/CT imaging for cancer screening.

The aim of this study was to evaluate the potential application of 18-fluorodeoxyglucose positron emission tomography (FDG PET) and PET/CT for cancer screening in asymptomatic individuals. The subjects consisted of 3631 physical check-up examinees (1947 men, 1684 women; mean age +/- SD, 52.1 +/- 8.2 y) with non-specific medical histories. Whole-body FDG PET (or PET/CT), ultrasound and tumor markers were performed on all patients. Focal hypermetabolic areas with intensities equal to or exceeding the level of FDG uptake in the brain were considered abnormal and interpreted as neoplasia. Follow-up periods were longer than one year. Among the 3631 FDG PET (including 1687 PET/CT), ultrasound and tumor markers examinations, malignant tumors were discovered in 47 examinees (1.29%). PET findings were true-positive in 38 of the 47 cancers (80.9%). In addition, 32 of the 47 cancers were screened with the PET/CT scan. PET detected cancer lesions in 28 of the 32 examinees. However, the CT detected cancer lesions in only 15 out of 32 examinees. The sensitivity of FDG PET in the detection of a wide variety of cancers is high. Most cancer can be detected with FDG PET at a resectable stage. CT of the PET/CT for localization and characteristics of the lesion showed an increased specificity of the PET scan. The use of ultrasound and tumor markers may complement the PET scan in cancer screening for hepatic and urologic neoplasms.

Limited value of 18F-2-deoxyglucose positron emission tomography to detect hepatocellular carcinoma in hepatitis B virus carriers.

BACKGROUND/AIMS: The differentiation of hepatocellular carcinoma from benign liver diseases in hepatitis B virus carriers by imaging studies based upon morphological aspects can be difficult. METHODOLOGY: FDG-PET (18F-2-deoxyglucose positron emission tomographies) were performed in 48 hepatitis B virus carriers to detect hepatocellular carcinoma and differentiate other benign liver diseases. In each patient, the focal liver lesion was visible by ultrasound and an elevated serum alpha-fetoprotein level was noted. Definite diagnosis was established after ultrasound-guided liver biopsy followed by histopathological examination. RESULTS: The histopathological examination revealed hepatocellular carcinoma in 36 patients and benign liver diseases in the remaining 12 patients. Twenty of 36 hepatocellular carcinomas were detectable by FDG-PET and none of 12 benign liver diseases were visualized by FDG-PET. The detection sensitivity of FDG-PET was not related to the echogenicity and size of hepatocellular carcinoma. CONCLUSIONS: FDG-PET is not sensitive to but is more specific than ultrasound and serum alpha-feto-protein level to detect hepatocellular carcinoma and differentiate from other benign liver diseases in hepatitis B virus carriers.

Comparison of FDG-PET and technetium-99m MIBI SPECT to detect metastatic cervical lymph nodes in well-differentiated thyroid carcinoma with elevated serum HTG but negative I-131 whole body scan.

The aim of this study was to evaluate the usefulness of 18-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) single photon emission computed tomography (SPECT) in detecting metastatic cervical lymph nodes (LN) in well-differentiated thyroid carcinoma (DTC) after total thyroidectomy and radioiodine-131 (I-131) treatments in patients with elevated serum human thyroglobulin (hTg) levels but negative I-131 whole body scan (WBS). Fifteen DTC patients underwent nearly total thyroidectomy and I-131 treatments with cervical LN metastases were included in this study. All subjects had negative I-131 WBS and elevated hTg levels (hTg > or = 10 microIU/ml) under thyroid-stimulating hormone (TSH) stimulation (TSH > or = 30 microIU/ml). FDG-PET could detect all of the 15 (100%) patients with metastatic cervical LN, but Tc-99m MIBI SPECT revealed lesions in only 9 out of 15 (60%) patients (p value < 0.05). This study demonstrated that FDG-PET is more sensitive than Tc-99m MIBI SPECT in detecting metastatic cervical LN in DTC with elevated serum hTg levels but negative I-131 WBS.

Colorectal cancer screening in asymptomatic adults: the role of FDG PET scan.

The aim of this study was to evaluate the potential application of 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) for colorectal cancer screening in asymptomatic individuals. The subjects consisted of 3210 physical check-up examinees (1736 men, 1474 women; mean age +/- SD, 53.2 +/- 8 y) with non-specific medical history. In the control group, 12 patients who had gastrointestinal symptoms with biopsy-proved colon carcinoma were recruited. Whole-body FDG PET was performed on all patients. Focal hypermetabolic areas with an intensity equal to or exceeding the level of FDG uptake in the brain and bladder were considered abnormal and interpreted as intraluminal neoplasia. Among the 3210 FDG PET examinations, advanced neoplasm was present in 20 examinations, including 2 tubular adenomas larger than 1 cm, 12 villous adenomas and 6 cancers. Of 6 examinees diagnosed with cancer, one had a Dukes stage A lesion, four had Dukes stage B lesion and one had a Dukes stage C lesion. In the control group, of 12 patients with biopsy-proved carcinoma followed by FDG PET scan, six had a Dukes stage B lesion, four had Dukes stage C lesion and two had a Dukes stage D lesion. The mean and standard deviation of standard uptake value (SUV) in colonic adenoma and carcinoma is 3.56 +/- 0.68 and 5.74 +/- 2.26, respectively. The sensitivity of using FDG PET in the detection of primary colorectal cancer is high. Primary colorectal cancer can be detected with FDG PET in a resectable stage. FDG PET could detect large size (> 0.7 cm) and pre-malignant change of colonic adenoma. It is possible to differentiate adenoma from carcinoma of colon by an increased rate of glycolysis (SUV) in carcinoma.

Differentiating solitary pulmonary metastases in patients with renal cell carcinomas by 18F-fluoro-2-deoxyglucose positron emission tomography--a preliminary report.

OBJECTIVE: This preliminary study was to evaluate the characteristics of indeterminate solitary pulmonary lesions in patients with renal cell carcinomas (RCC) using (18)F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET). MATERIAL AND METHODS: Fifteen patients with RCC were found to have solitary pulmonary lesions with indeterminate chest X-ray and CT findings. Pulmonary metastases were suspected in all cases so whole body surveys with FDG-PET were performed. RESULTS: FDG-PET correctly identified 9 true-positive and 4 true-negative cases. However, FDG-PET failed to interpret 1 false-positive and 1 false-negative case. Standard uptake values (SUV) were used as parameters to differentiate the solitary pulmonary lesions. Using SUV >2.5 as the cutoff to diagnose malignancy, the sensitivity, specificity, and accuracy of FDG-PET were 90, 80, and 87%, respectively. CONCLUSION: We conclude that FDG-PET is an accurate modality to differentiate solitary pulmonary lesions in patients with RCC.