Prognostic Significance of Standardized Uptake Value on 18Fluorine-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Patients with Nasopharyngeal Carcinoma.

The aim of this study was to investigate the prognostic significance of standardized uptake value (SUV) on 18 fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma (NPC). Thirty-four patients who have histologically proven NPC and underwent 18F-FDG PET/CT were included in this study. After 18F-FDG PET/CT, all the patients received radiation therapy and 32 of them received concomitant weekly chemotherapy. The maximum SUV (SUVmax) at the primary tumor and the SUVmaxof the highest neck nodes were determined. The SUVmax-T ranged from 5.00 to 30.80 (mean: 15.37 ± 6.10) and there was no difference between SUVmax-T values for early and late stages (P = 0.99). The SUVmax-N ranged from 3.10 to 23.80 (mean: 13.23 ± 5.76). There was no correlation between SUVmax-T and SUVmax-N (r = 0.111, P = 0.532). There was no difference between the SUVmax-T and the positivity of neck lymph nodes (P = 0.169). The ability of SUVmaks-N to predict stage was obtained by a receiver operating characteristic (ROC) analysis. The area under the curve is 0.856 and the best cut-off value is 7.88. There was a good correlation between SUVmax-N and stage. While the mean SUVmax-T for the alive patients was slightly lower than that for the dead (14.65 ± 5.58 vs. 20.30 ± 7.92, P = 0.061), the difference between the groups was not statistically significant. Furthermore, there was no statistically significant difference for SUVmax-N between these two groups (P: 0.494). Cox-regression analysis showed that an increase in SUVmax-T and SUVmax-N was associated with death risk (relative risk [RR]: 1.13, P = 0.078 and RR: 1.052, P = 0.456, respectively). SUVmax-T and SUVmax-N were independent prognostic factors for survival in NPC patients. This will help the clinicians in choosing suitable candidates for more aggressive treatment modalities.

Laryngeal squamous cell cancer with late presentation of isolated liver metastasis on fluorodeoxyglucose positron emission tomography-computed tomography.

Laryngeal cancer is the second most common type of head and neck malignancy, representing approximately 45% of all head and neck cancers. Hematogenous spread to the liver rarely occurs without evidence of pulmonary and bone disease. We report a patient who had been treated 7 years earlier for laryngeal squamous cell cancer and who had isolated liver metastasis on fluorodeoxy D-glucose positron emission tomography-computed tomography.

A case of sarcoidosis diagnosed by positron emission tomography/computed tomography.

Sarcoidosis is a multisystem granulomatous disorder of unknown cause which may affect any organ or system but primarily involve the lungs and the lymphatic system. Extrapulmonary sarcoidosis represents approximately 30-50% of patients. We report the case of a 51-year-old female who presented with increasing complaints of a cough, weakness, weight loss, and chest pain and who was found to have a suspicious lesion on thorax computed tomography(CT). Fluorodeoxyglucose (FDG) positron emission tomography/CT performed for diagnostic purposes demonstrated increased FDG accumulation at the bilateral enlarged parotid and lacrimal gland and in the reticulonodular infiltration area located in the left lung as well as multiple lymphadenopathies with increased FDG accumulation. There were also hepatosplenomegaly and splenic uptake. Skin biopsy showed noncaseating granulomas, and the patient was diagnosed as stage 2 sarcoidosis.

Depiction of ventriculoperitoneal shunt obstruction with single-photon emission computed tomography/computed tomography.

An 83-year-old male patient with ventriculoperitoneal shunt underwent radionuclide shunt study using single-photon emission computed tomography/computed tomography (SPECT/CT) to evaluate the shunt patency. The planar images showed activity at the cranial region and spinal canal but no significant activity at the peritoneal cavity. However, SPECT/CT images clearly demonstrated accumulation of activity at the superior part of bifurcation level with no activity at the distal end of shunt as well as no spilling of radiotracer into the peritoneal cavity indicating shunt obstruction. SPECT/CT makes the interpretation of radionuclide shunt study more accurate and easier as compared with traditional planar images.

The role of FDG-PET/CT in differentiated thyroid cancer patients with negative iodine-131 whole-body scan and elevated anti-Tg level.

AIM: In the follow-up of differentiated thyroid cancer (DTC) after a successful total-near total thyroidectomy and I-131 ablation therapy, anti-thyroglobulin antibodies (anti-Tg) may be persistently or progressively increased in the patients with an undetectable serum thyroglobulin (Tg) level. In these cases, further investigation was performed to search for recurrence/metastases. The aim of our study was clarifying the role of FDG-PET/CT in detecting recurrence/metastasis in patients with DTC with negative serum Tg and elevated anti-Tg level. MATERIALS AND METHODS: A total of 40 patients (32 female, 8 male; mean age: 43.15 years (22-65); mean age at diagnosis: 39.08 (16-64)) with DTC who had undetectable serum Tg and elevated anti-Tg level after a successful initial therapy were included in the study. All of the patients had serum anti-Tg of >40 IU/ml and underwent FDG-PET/CT to search for recurrence/metastasis. RESULTS: Twenty patients (50 %) had recurrence/metastasis on FDG-PET/CT while the other 20 had no pathologic findings. Of the 20 patients who had positive FDG-PET/CT, 12 had a histopathological final diagnosis of which 11 were true positive (TP) and 1 was false positive (FP). On the other hand, 16 of the 40 patients had a histopathological final diagnosis of which 11/16 had TP, 1/16 FP, 3/16 false negative (FN) and 1/16 true negative (TN) findings by PET/CT. The final diagnosis was made by clinical follow-up in the remaining 24 patients. Of these, 8 patients were PET positive, and in 1 (12.5 %) of 8 patients a decrease in serum anti-Tg level, in 2 (25 %) patients a saw-toothed pattern and in 5 (62.5 %) a progressive increase in the serum anti-Tg level were noted during the follow-up. Of the 16 of 24 patients who were diagnosed by clinical follow-up, in 8 a (50 %) decrease in serum anti-Tg level, in 6 (37.5 %) a saw-toothed pattern, and in 2 (12.5 %) a progressively increased anti-Tg level was seen. Of the 40 patients, 14 (35 %) had a diagnosis of recurrence/metastasis finally, with PET/CT detecting 11 (78.6 %) of them. CONCLUSION: The value of a persistently or progressively increased serum anti-Tg level in the follow-up of DTC in the prediction of recurrence/metastasis is controversial. However, it is reported that FDG-PET can be useful in the detection of recurrence/metastasis. We conclude from the available data that PET/CT can be effectively used in the detection of recurrence/metastasis in the follow-up of patients with DTC and negative serum Tg and a persistently/progressively increased anti-Tg level. Besides, one half of the patients were FDG negative, meaning that further studies are needed to assess the prognostic-clinical value of PET negativity.

Appearance of recurrent cardiac myxofibrosarcoma on FDG PET/CT.

Primary cardiac sarcomas are extremely rare tumors. In this case report, we presented the condition of a 37-year-old male patient diagnosed with myxofibrosarcoma after histopathologic evaluation of the left atrium mass excision. FDG PET/CT was performed and showed recurrent hypermetabolic lesions in the left atrial wall and right anterior mediastinal region.

FDG and FDG-labelled leucocyte PET/CT in the imaging of prosthetic joint infection.

PURPOSE: The demand for arthroplasty is rapidly growing as a result of the ageing of the population. Although complications such as heterotrophic ossification, fracture and dislocation are relatively rare, differentiating aseptic loosening, the most common complication of arthroplasty from infection, is a major challenge for clinicians. Radionuclide imaging is currently the imaging modality of choice since it is not affected by orthopaedic hardware. Whereas FDG PET/CT imaging has been widely used in periprosthetic infection, it cannot discriminate aseptic from septic inflammation. In this study we aimed to evaluate the role of FDG PET/CT and FDG-labelled leucocyte PET/CT in the diagnosis of periprosthetic infection. METHODS: Of 54 patients with painful joint arthroplasty who were imaged by FDG PET/CT for diagnosis of periprosthetic infection examined, 46 (36 women, 10 men; mean age 61.04 ± 12.2 years, range 32-89 years) with 54 painful joint prostheses (19 hip, 35 knee) with grade 2 (above liver uptake) FDG accumulation on FDG PET/CT were included in the study and these 46 patients also underwent FDG-labelled leucocyte PET/CT. Final diagnoses were made by histopathological-microbiological culture or clinical follow-up. RESULTS: The final diagnosis showed infection in 15 (28%) and aseptic loosening in 39 (72%) of the 54 prostheses. FDG PET/CT was found to have a positive predictive value of 28% (15/54). Since patients with no FDG uptake on FDG PET/CT were excluded from the study, the sensitivity, specificity, negative predictive value and accuracy could not be calculated. The sensitivity, specificity, and positive and negative predictive values of FDG-labelled leucocyte PET/CT were 93.3% (14/15), 97.4% (38/39), 93.3% and 97.4%, respectively. CONCLUSION: Since FDG is not specific to infection, the specificity of FDG PET/CT was very low. FDG-labelled leucocyte PET/CT with its high specificity may be a useful method and better than labelled leucocyte scintigraphy in periprosthetic infection imaging.