PET and PET-CT imaging in infection and inflammation: Its critical role in assessing complications related to therapeutic interventions in patients with cancer.

Over the past decade, there has been an increasing evidence of false-positive FDG uptake in several infectious diseases and aseptic inflammatory processes. With the widespread application of FDG-PET imaging in oncology, the interpreting physicians have come across these conditions frequently leading to false-positive diagnosis. Such conditions can coexist with metastatic lesions in patients with cancer, and hence, early and accurate diagnosis or exclusion of infection and inflammation is of utmost importance for the optimal management of these patients. Also, this powerful imaging modality can play an invaluable role for the appropriate management of these complicated benign conditions. The present communication on this non-oncological application of FDG is intended as an educative primer for practicing oncologists on this very important aspect of PET-CT imaging with an ultimate aim for bettering patient management.

Challenges in integrating 18FDG PET-CT into radiotherapy planning of head and neck cancer.

Radiotherapy forms one of the major treatment modalities for head and neck cancers (HNC), and precision radiotherapy techniques, such as intensity-modulated radiotherapy require accurate target delineation to ensure success of the treatment. Conventionally used imaging modalities, such as X-ray computed tomography (CT) and magnetic resonance imaging are used to delineate the tumor. Imaging, such as positron emission tomography (PET)-CT, which combines the functional and anatomic modalities, is increasingly being used in the management of HNC. Currently, 18-fluorodeoxyglucose is the most commonly used radioisotope, which is accumulated in areas of high glucose uptake, such as the tumor tissue. Because most disease recurrences are within the high-dose radiotherapy volume, defining a biological target volume for radiotherapy boost is an attractive approach to improve the results. There are many challenges in employing the PET-CT for radiotherapy planning, such as patient positioning, target edge definition, and use of new PET tracers, which represent various functional properties, such as hypoxia, protein synthesis, and proliferation. The role of PET-CT for radiotherapy planning is ever expanding and more clinical data underlining the advantages and challenges in this approach are emerging. In this article, we review the current clinical evidence for the application of functional imaging to radiotherapy planning and discuss some of the current challenges and possible solutions that have been suggested to date.

Metabolic test with fluorine-18-fluorodeoxyglucose in staging and detection of residual tumor or recurrence in Hodgkin lymphoma

OBJECTIVE: The metabolic test using 18F-fluorodeoxyglucose is a useful tool for the management of patients with Hodgkin lymphoma, either for staging purposes or for the evaluation of suspicious masses that can frequently occur after treatment. The aim of the present study was to investigate the value of the 18F-fluorodeoxyglucose test performed with a dual-head coincident gamma camera (CGC-PET with fluorodeoxyglucose) for the staging and the detection of residual tumor of patients with Hodgkin lymphoma. METHODS: Thirty-eight consecutive patients were included in this retrospective study; the metabolic test comprising CGC-PET with FDG was done in 18 patients for staging work-up (Group 1), and the results were compared to conventional clinical staging procedures that included computed tomography scans and bone marrow biopsy. The remaining 20 patients were evaluated with CGC-PET with fluorodeoxyglucose due to the presence of residual masses or a new lesion (Group 2). RESULTS: The 18F-Fluorodeoxyglucose metabolic test, CGC-PET with fluorodeoxyglucose, upstaged 5 (27 percent) of the Group 1 patients and detected more lesions (45) than conventional methods of staging (33). Of the 20 patients in Group 2, 11 had positive18F-fluorodeoxyglucosetests, and a viable tumor was confirmed in 9 patients. Regarding the 9 patients with negative fluorodeoxyglucose metabolic tests, the 1-year probability of recurrence was 11.8 percent. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the CGC-PET with fluorodeoxyglucose test were 90 percent, 80 percent, 82 percent, 89 percent, and 85 percent respectively. CONCLUSIONS: The metabolic test comprising CGC-PET with fluorodeoxyglucose had a higher diagnostic accuracy than conventional methods in the staging of Hodgkin lymphoma and thus is a valuable noninvasive tool for the diagnosis of suspicious lesions.

OBJETIVO: O estudo metabólico com 18F-fluorodeoxiglicose é uma ferramenta útil para o manejo de portadores de linfoma de Hodgkin, tanto como método auxiliar no estadiamento da doença, quanto na avaliação de massas suspeitas encontradas após tratamento. O objetivo deste estudo foi investigar o valor do estudo com 18F-fluorodeoxiglicose em gama câmara híbrida no estadiamento e na detecção de tumor residual em pacientes com linfoma de Hodgkin. MÉTODOS: Trinta e oito pacientes foram incluídos neste estudo retrospectivo, 18 foram avaliados com o estudo metabólico durante o estadiamento (Grupo 1), sendo os resultados do estudo comparados com os obtidos com o estadiamento convencional, que incluiu tomografia e biópsia de medula óssea. Os 20 pacientes restantes realizaram o estudo metabólico devido à presença de massa residual ou de nova lesão suspeita (Grupo 2). RESULTADOS: O estudo metabólico aumentou o estádio de cinco (27 por cento) dos pacientes do Grupo 1 e pôde detectar mais lesões que os métodos convencionais de estadiamento (45 lesões detectadas com 18F-fluorodeoxiglicose versus 33 lesões métodos convencionais). Nos 20 pacientes do Grupo 2, 11 foram 18F-fluorodeoxiglicose positivos e tumor viável foi confirmado em 9 pacientes. Nos 9 pacientes com estudo metabólico negativo, a probabilidade de recidiva em um ano foi de 11.8 por cento. A sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e a acurácia do estudo metabólico foram de 90 por cento, 80 por cento, 82 por cento, 89 por cento e 85 por cento respectivamente. CONCLUSÕES: O estudo com 18F-fluorodeoxiglicose apresentou melhor acurácia que os métodos convencionais de estadiamento do Linfoma de Hodgkin e foi útil para o diagnóstico não-invasivo de lesões suspeitas.

Unilateral Autosomal Dominant Polycystic Kidney Disease with Contralateral Renal Agenesis: A Case Report

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease. There are some reports in the literature concerning unilateral ADPKD. However, in adults, only a few cases of unilateral ADPKD with agenesis of contralateral kidney have been reported. We present a case of unilateral ADPKD with agenesis of contralateral kidney in a 66-yr-old man. Radiographic images showed the enlarged right kidney with multiple variable-sized cysts and the absence of the left kidney. The diagnosis of ADPKD was confirmed by the family screening. The patient received maintenance hemodialysis for endstage renal disease. We report a case of unilateral ADPKD associated with contralateral renal agenesis in a 66-yr-old male patient with a literature review.