Dimitrios Karantanis

The value of quantifying 18F-FDG uptake in thyroid nodules found incidentally on whole-body PET-CT.

ObjectiveTo determine if quantification of [18F]fluorodeoxyglucose (18F-FDG) uptake in a thyroid nodule found incidentally on whole-body 18F-FDG positron emission tomography–computed tomography (PET–CT) can be used to discriminate between malignant and benign aetiology. MethodsA retrospective review of all patients with focally high uptake in the thyroid as an incidental finding on 18F-FDG PET–CT from May 2003 through May 2006. The uptake in the nodules was quantified using the maximum standardized uptake value (SUVmax). The aetiology was determined by cytology and/or ultrasound, or on histopathology. ResultsIncidental focally high uptake was found in 79/7347 patients (1.1%). In 31/48 patients with adequate follow-up, a benign aetiology was determined. Median SUVmax for the benign group was 5.6, range 2.5–53. Malignancy was confirmed in 15/48 patients. The malignancies were papillary thyroid carcinoma in 12, metastasis from squamous cell carcinoma in one, and lymphoma in two. Median SUVmax for the malignant lesions was 6.4, range 3.5–16. Cytology suspicious for follicular carcinoma was found in 2/48 patients. No statistical difference (P=0.12) was found among the SUVmax between the benign and malignant groups. ConclusionFocally high uptake of 18F-FDG in the thyroid as an incidental finding occurred in 1.1% of the patients. Malignancy was confirmed or was suspicious in 17/48 (35%) of the patients that had adequate follow-up. There was no significant difference in the SUVmax between benign and malignant nodules.

Clinical Significance of Diffusely Increased 18F-FDG Uptake in the Thyroid Gland

Our purpose was to determine the clinical significance of diffusely increased 18F-FDG uptake in the thyroid gland as an incidental finding on PET/CT. Methods: All patients who were found to have diffuse thyroid uptake on 18F-FDG PET/CT in our institution between November 2004 and June 2006 were investigated and compared with an age- and sex-matched control group. The 18F-FDG uptake in the thyroid was semiquantified using maximum standardized uptake value and correlated to the available serum thyroid-stimulating hormone (TSH) and thyroid peroxidase (TPO) antibody levels using regression analysis. Results: Of the 4,732 patients, 138 (2.9%) had diffuse thyroid uptake. Clinical information was available for 133 of the 138 patients. Sixty-three (47.4%) had a prior diagnosis of hypothyroidism or autoimmune thyroiditis, of whom 56 were receiving thyroxine therapy. In the control group, consisting of 133 patients with no thyroid uptake, there were 13 (9.8%) with a prior diagnosis of hypothyroidism, 11 of whom were receiving thyroxine therapy. In the study group, 38 (28.6%) of 133 patients did not undergo any further investigation for thyroid disease, whereas 32 (24.1%) of 133 patients were examined for thyroid disease after PET. Nineteen were found with autoimmune thyroiditis or hypothyroidism, and replacement therapy was initiated in 12. No significant correlation was found between maximum standardized uptake value and TSH (P = 0.09) or TPO antibody (P = 0.68) levels. Conclusion: The incidental finding of increased 18F-FDG uptake in the thyroid gland is associated with chronic lymphocytic (Hashimotos) thyroiditis and does not seem to be affected by thyroid hormone therapy. SUV correlated neither with the degree of hypothyroidism nor with the titer of TPO antibodies.

18F-FDG PET in the management of patients with anaplastic thyroid carcinoma.

BACKGROUND Anaplastic thyroid carcinoma (ATC) is one of the most aggressive solid tumors in humans. The use of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) in ATC has not been studied, and only a few case reports have been published. The objective of this study was to investigate the potential contribution of 18F-FDG PET to the clinical management of patients with ATC. METHODS All patients with ATC studied with 18F-FDG PET from August 2001 through March 2007 were included. The PET results were correlated with computed tomography, ultrasound, magnetic resonance imaging, bone scan, histology, and clinical follow-up. The FDG uptake was semiquantified as maximum standard uptake value. Any change in the treatment plan as a direct result of the PET findings as documented in the clinical notes was recorded. RESULTS Sixteen patients were included. True-positive PET findings were seen for all primary tumors, in all nine patients with lymph node metastases, in five out of eight patients with lung metastases, and in two patients with distant metastases other than lung metastases. In 8 of the 16 patients, the medical records reported a direct impact of the PET findings on the clinical management. CONCLUSIONS ATC demonstrates intense uptake on 18F-FDG PET images. In 8 of the 16 patients (50%), the medical records reported a direct impact of the PET findings on the management of the patient. PET may improve disease detection and have an impact on the management of patients with ATC relative to other imaging modalities.

The Value of [18F]Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Extranodal Natural Killer/T—Cell Lymphoma

PURPOSE To our knowledge, there are no published data pertinent to the use of [(18F)]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in patients with natural killer (NK)/T-cell lymphoma. The purpose of this study was to assess the value of FDG PET/CT in this aggressive type of non-Hodgkin lymphoma. PATIENTS AND METHODS All patients with NK/T-cell lymphoma referred for FDG PET/CT at our institution from July 2001 to July 2006 were retrospectively studied. PET/CT examinations were blindly reviewed by 2 experienced readers. The results were compared with the status of the disease, which was determined after evaluation of biopsy, laboratory, clinical and conventional imaging examination, and follow-up results. PET/CT results were thereby classified as true-positive, true-negative, false-positive, or false-negative. The degree of FDG uptake in the positive lesions was semiquantified using maximum standard uptake value (SUV(max)). RESULTS Twenty-one PET/CT examinations were performed in 10 patients with NK/T-cell lymphoma. For nasal disease, PET/CT was true-positive in 5 cases, true-negative in 15 cases, and positive but unconfirmed in 1 case. For extranasal disease, PET/CT was true-positive in 3 cases, true-negative in 16 cases, and false-negative in 2 cases. The mean SUV(max) in PET-positive lesions in nasal cavities or paranasal sinuses was 16 gm/mL (range, 5-25 gm/mL; median, 19.3 gm/mL). In extranasal disease, the mean SUV(max) was 10.9 gm/mL (range, 4.6-34.1 gm/mL; median, 5.6 gm/mL). CONCLUSION Viable NK/T-cell lymphoma is intensely FDG hypermetabolic. PET/CT appears to be sensitive for the detection of disease in the nasopharynx and, to a lesser extent, in extranasal sites.

18F-FDG PET/CT in primary central nervous system lymphoma in HIV-negative patients

ObjectiveTo determine the value of 18F-FDG PET/CT in the different manifestations of primary central nervous system lymphoma (PCNSL) in HIV-negative patients. MethodsAll PCNSL and HIV-negative patients referred for PET/CT in our institution from July 2001 to June 2006 were retrospectively studied. PET/CT examinations were reviewed by two experienced readers and evaluated for each possible anatomical site of nervous system involvement: cerebral, spinal/nerve and ocular. PET/CT results were characterized as true positive or negative and false positive or negative according to the status of the disease, which was determined after the evaluation of biopsies, laboratory, clinical and imaging examinations, and follow-up. ResultsForty-two PET/CT examinations were carried out in 25 PCNSL patients. For intracerebral disease, PET/CT was true positive in 13 cases, true negative in 27 and false negative in two. For disease involving spinal cord and/or nerves, PET/CT was true positive in four cases, true negative in 37 and false negative in one. For ocular disease, PET was true positive in only one case and false negative in four. The sensitivity of PET/CT in detecting active disease in the brain was 87% (13/15), in the spine/nerves 80% (4/5), and in the eyes only 20% (1/5). ConclusionPET/CT seems to be sensitive for the detection of viable intracerebral as well as for spinal and peripheral nerve disease, but not for the detection of ocular involvement.

Contribution of F-18 FDG PET-CT in the detection of systemic spread of primary central nervous system lymphoma

Purpose: Primary central nervous system lymphoma (PCNSL) accounts for ∼3% of all primary brain tumors and 1% of all non-Hodgkin lymphomas. Detection of systemic spread of PCNSL, although rare (4%), is very important since therapy is usually modified. Contrast-enhanced computed tomography (CT) is commonly used for systemic staging of PCNSL. No previous case report is available in the published literature elaborating the potential contribution of F-18 FDG PET in systemic staging of PCNSL. The purpose of this case report was to document the potential usefulness of F-18 FDG-PET in the detection of occult systemic involvement in PCNSL. Materials and Methods: A 50-year-old, immunocompetent, male patient completed successful treatment of PCNSL. As part of a routine pretransplant evaluation he had an F-18 FDG PET coregistered with CT (PET-CT). The PET-CT results were then compared with those of contrast-enhanced CT of the chest, abdomen, and pelvis. Results: The PET-CT examination detected multiple sites of extranodal systemic disease that were not seen in the contrast-enhanced CT of the chest, abdomen, and pelvis (both studies were performed within 24 hours of each other). Percutaneous ultrasound guided biopsy confirmed the presence of systemic spread of PCNSL. The patients subsequent therapy was modified to include rituximab with cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP). A follow up PET-CT confirmed resolution of systemic spread. Conclusion: F-18 FDG PET coregistered to CT may be a useful examination in the detection and monitoring for systemic spread of the disease in PCNSL patients.

18F-FDG PET and PET/CT in Burkitt's lymphoma

OBJECTIVE To explore the value of (18)F fluorodeoxy-glucose (FDG) positron emission tomography (PET) in Burkitts lymphoma. METHODS All Burkitts lymphoma patients referred for FDG PET or FDG PET/computed tomography (CT) exams at our institution from June 2003 to June 2006 were included. Selected patients were followed and clinical information was reviewed retrospectively. Results from FDG PET-PET/CT, as blindly reviewed by a consensus of two experienced readers, were compared with the status of the disease as determined by other laboratory, clinical and imaging exams and clinical follow-up. FDG PET-PET/CT results were classified as true positive or negative and false positive or negative. The degree of FDG uptake in the positive lesions was semiquantified as maximum standard uptake value (SUVmax). RESULTS Fifty-seven FDG PET-PET/CT exams were done in 15 patients. Seven exams were done for initial staging, 8 during and 14 after the completion of therapy, and 28 for disease surveillance. For nodal disease FDG PET-PET/CT was true positive in 8, true negative in 47 and false positive in 2 exams (sensitivity 100%, specificity 96%). For extranodal disease FDG PET-PET/CT was true positive in 6, true negative in 48 and false positive in 3 exams (sensitivity 100%, specificity 94%). The mean SUVmax for the positive nodal lesions was 15.7 (range 6.9-21.7, median 18.5) and for extranodal lesions was 14.2 (range 6.2-24.3, median 12.4). CONCLUSIONS FDG PET-PET/CT is sensitive for the detection of viable disease in Burkitts lymphoma. Affected areas demonstrated high degree of uptake that was reversible upon successful implementation of treatment.

The Prognostic Value of 2-Deoxy-2-[18F]Fluoro-d-Glucose Positron Emission Tomography in Patients With Suspected Residual or Recurrent Medullary Thyroid Carcinoma

PurposeTo explore the prognostic value of 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography (PET) in patients with suspected residual or recurrent medullary thyroid carcinoma (MTC).ProceduresThis retrospective study included all patients with MTC examined with FDG-PET at Mayo Clinic, Rochester, Minnesota, from October 1999 to March 2008. The PET results were compared with other imaging studies and clinical findings, including carcinoembryonic antigen and calcitonin levels.ResultsTwenty-nine patients with MTC were included. PET was positive in 14 patients, with follow-up information for 11; six died from metastatic disease, four had disease progression, and one remained in stable condition. PET was negative in 15 patients, with follow-up for 12; one had recurrent disease, and 11 had no evidence of clinical disease. Calcitonin doubling time was shorter for PET-positive than for PET-negative patients.ConclusionFDG-PET has high prognostic value in patients with suspected residual or recurrent MTC.

Focal F-18 fluoro-deoxy-glucose accumulation in the lung parenchyma in the absence of CT abnormality in PET/CT

Objective: To demonstrate 3 cases of artifactual focal F-18 fluoro-deoxy-glucose accumulation in the lung parenchyma in the absence of any computed tomographic (CT) abnormality. Materials and Methods: Three patients were examined: a 30-year-old man who had a positron emission tomography (PET)/computed tomography for restaging a biopsy-proven recurrence of head and neck cancer, a 68-year-old woman who was referred for initial staging of esophageal carcinoma, and a 57-year-old man who had a PET/computed tomography for initial staging of melanoma. In each case, there was intense focal activity in the lung parenchyma with no corresponding CT abnormality. Each patient was further evaluated with a repeat PET scan in days 1 and 3 in the first 2 cases and with a delayed repeat acquisition in the third case. Patients were followed for 24, 10, and 1 month, respectively. Results: In the first 2 cases, the abnormal focal activity in the lungs had resolved in the repeat study. In the third case, the focus of increased activity in the lung had moved more peripherally in the delayed acquisition. Clinical follow-up was negative for disease in the corresponding pulmonary parenchymal sites. Conclusions: The finding of significant focal accumulation of fluoro-deoxy-glucose in the lung parenchyma in the absence of corresponding CT abnormality was artifactual. This was likely due to injection technique and the creation of particulate embolus. Positron emission tomography/Computed tomographic readers should be aware of this type of artifact to avoid misinterpretation.

Relationship among glycolytic phenotype, grade, and histological subtype in ovarian carcinoma.

Purpose: Knowing the glycolytic phenotype of cancers is important for the appropriate use of F-18 FDG PET/CT imaging. This study was performed to determine the influence of tumor grade and histology on the glycolytic phenotype of epithelial ovarian cancer patients. Materials and Methods: Only histopathologically confirmed epithelial ovarian cancer patients, with no other concurrent malignancies, who had F-18 FDG PET/CT either before or at least 3 months after any therapeutic intervention and had confirmed measurable disease of >1 cm were included. The F-18 FDG PET/CT uptake was determined as maximum standard uptake value (SUVmax) at the pathologically confirmed site of disease or in the most active lesion. SUVmax was correlated to tumor grade and histology. Results: Of 171 ovarian cancer patients, 42 referred for F-18 FDG PET/CT scans between January 2003 and December 2010 were eligible for inclusion. Histologic diagnosis most frequently revealed the serous subtype (n = 32) and grade III (n = 28) epithelial ovarian cancer. Overall, ovarian carcinomas exhibited a strong glycolytic phenotype (average SUVmax, 7.6 g/mL). The SUVmax averaged 7.76 g/mL, 6.76 g/mL, and 7.95 g/mL for Grade I, II, and III, respectively. There was no statistically significant correlation between tumor SUVmax and the histologic tumor grade (P = 0.74). No statistically significant differences were found between the tumor SUVmax of serous and endometrioid subtypes (P = 0.53). For other histology subtypes, no statistic evaluation was possible due to the low number of cases. Conclusions: The glycolytic phenotype in epithelial ovarian cancer, expressed as SUVmax, is strong. However, tumor FDG uptake is unrelated to tumor grade and histologic subtype implying that F-18 FDG PET/CT cannot be used to predict tumor aggressiveness or histology.