Ahmed Shamim

Clinical applications of PET and PET/CT in pediatric malignancies

The common childhood cancers are leukemia, CNS tumors, lymphomas, soft-tissue tumors (such as rhabdomyosarcoma and fibrosarcoma), neuroblastoma, malignant bone tumors, germ cell tumors with neoplasms of gonads and hepatic tumors. Usually the conventional imaging modalities, such as x-ray, ultrasound, computed tomography (CT) and MRI, are being routinely used for the management of these pediatric malignancies. However, most of these modalities provide structural information and are lacking in functional/metabolic status of these malignancies. Recently, PET and PET/CT have emerged as a functional diagnostic imaging modality for the management of various cancers in adult population. Up to now most of the data published in the literature are on PET alone. PET used in conjunction with CT is useful as it provides an enhanced view of the anatomical details and the malignant focus then can be located with highest accuracy. PET and PET/CT has been found to be useful in, for example, CNS tumors, lymphomas, soft-tissue tumors, neuroblastoma, malignant bone tumors and germ cell tumors. PET/CT has a limited role in early diagnosis, however, it plays an important role in initial staging, treatment response evaluation and detection of metastatic disease in these cancers. Despite the fact that PET/CT has better diagnostic value when compared with conventional imaging, such as CT and MRI, in the management of many pediatric cancers, there are certain limitations. PET/CT has a limited role in detection of lesions smaller than 5 mm, well-differentiated tumors and tumors with low metabolic rate. Many infections and inflammation can lead to false-positive PET/CT results. In the present review we will discuss the various clinical indications of PET and PET/CT in pediatric cancers.

Role of FDG PET-CT in recurrent renal cell carcinoma.

AimTo determine the efficacy of positron emission tomography-computed tomography using F-18 fluoro-deoxy-glucose (F-18 FDG PET-CT) in diagnosing the recurrence of renal cell carcinoma (RCC) in patients treated earlier with partial or radical nephrectomy. MethodsWe assessed 63 patients with suspected recurrent RCC after nephrectomy. PET-CT findings were interpreted as positive if the focal area of FDG uptake in the abdomen or outside the abdomen was more than the surrounding background tissue. The final diagnosis of the recurrence of RCC was based on histological examination and/or clinical follow-up and conventional imaging modalities. ResultsA total of 103 PET-CT studies were done in these 63 patients, of which 63 studies were true positive, 30 studies were true negative, seven studies were false negative and remaining three studies were false positive. In 63 true-positive scans, PET-CT showed 109 lesions. Of these, 28 lesions were in the lungs, 21 lesions were at a locoregional site, 21 were in the bones, 12 in the retroperitoneal lymph nodes and 27 at other sites. The sensitivity, specificity and accuracy of PET-CT were 90, 91 and 90%, respectively. ConclusionOur results seem to confirm the useful role of PET-CT in the evaluation of post-surgical recurrence in patients who had undergone radical surgery for RCC.

Role of FDG-PET/CT in detection of recurrent disease in colorectal cancer.

BackgroundOne-third of patients with colorectal cancer (CRC) are likely to have a recurrence within the first 1–2 years. Conventional imaging modalities have limitations in detecting recurrent disease early. The purpose of this study was to assess the usefulness of fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in the detection of recurrence in patients with CRCs. MethodsOne hundred and eighty-three patients, who were earlier treated with surgery and/or chemotherapy/radiotherapy, underwent 269 PET/CT studies for the detection of recurrence. The final diagnosis was made on the basis of histological analysis or clinical and imaging follow-up. ResultsThe sensitivity, specificity, accuracy, positive predictive value, and negative predictive value in detecting recurrent CRC using 18F-FDG-PET/CT were 87, 90, 88, 93, and 80%, respectively. PET/CT was found to have limitations in detecting microscopic disease and small-sized lesions. The common cause of false-positive PET/CT results was infective and inflammatory pathology in our setup. ConclusionPET/CT showed high sensitivity, specificity, and accuracy for the detection of recurrent disease in patients, who were earlier treated for CRC. PET/CT can be considered as a useful diagnostic tool in these patients.

Role of rhenium-188 tin colloid radiosynovectomy in patients with inflammatory knee joint conditions refractory to conventional therapy

AimTo evaluate the treatment response of rhenium-188 (188Re) tin colloid radiosynovectomy (188Re-RSV) in patients with inflammatory knee joint conditions refractory to conventional treatment. Materials and methodsSixty-one knee joints in 48 patients with chronic synovitis caused by various inflammatory knee joint diseases refractory to conventional therapy were included in this prospective study. All patients were assessed clinically for pain, tenderness, joint swelling, mobility, analgesic intake, and blood pool activity on bone scan. Different scores were assigned to all these parameters. RSV of knee joint was done using intra-articular injection of 555 MBq of 188Re tin colloid. Response was assessed at 3, 6, and 12 months using various clinical parameter scores and blood pool bone scan mentioned above and categorized as responders and nonresponders on the basis of change in percentage of cumulative scores. ResultsOf the 61 joints, 57 were responder and four were nonresponder at 3-month post-RSV. Out of 57 responders, seven had recurrence on further follow-up (three at 6 months and four at 12 months). There was a statistically significant reduction in clinical parameters cumulative scores at 3, 6, and 12 months when compared with baseline (P<0.0001) in responder group. Blood pool scinitgraphy also showed decrease in blood pool activity compared with the baseline. There was statistically significant association between the responder group and shorter duration of disease (P=0.011). Patients having normal or minor X-ray changes, little or no swelling, mild tenderness, and better mobility were independently associated with good response. Conclusion188Re tin colloid synovectomy is a useful treatment modality in patients with chronic inflammatory knee joint conditions refractory to conventional treatment. Patients with shorter duration of disease, normal or minor X-ray findings, little or no swelling, mild tenderness, and better mobility are better candidates for RSV.

FDG PET/CT evaluation of treatment response in patients with recurrent colorectal cancer.

Aim: To evaluate the treatment response in patients with recurrent colorectal cancer (CRC) using FDG PET/CT. Materials and Methods: A total of 32 recurrent CRC patients (21 males, 11 females; mean age, 52.8 years) were included in this retrospective study. All patients underwent a baseline and follow-up FDG PET/CT scans after chemotherapy. Of 32 patients, 23 patients had follow-up carcinoembryonic antigen (CEA) levels. Results: On qualitative analysis of baseline and follow-up FDG PET/CT studies, there were 20 nonresponders and 12 were responders. On quantitative analysis, there were 19 nonresponders and 13 were responders. In responders, baseline and follow-up mean SUVmax were 11.8 ± 10.1 and 3.7 ± 4.1, respectively (significant decrease, P = 0.001). Among nonresponders, baseline and follow-up mean SUVmax were 8.1 ± 5.2 and 14.1 ± 9.0, respectively (significant increase, P = 0.003). There was no association between response and different factors like age, sex, diagnosis, extent of the lesions, and number of lesions. Conclusion: FDG PET/CT appears to be useful modality in evaluating chemotherapy response and can differentiate responders from nonresponders in recurrent CRC patients.

FDG PET/CT in detection of adrenal metastasis in patients with renal cell carcinoma.

Aim: Adrenal metastasis in renal cell carcinoma (RCC) is uncommon. The present study was aimed to evaluate the role of fluoro-deoxy-glucose positron emission tomography (FDG PET)/computed tomography (CT) in the detection of adrenal metastasis in patients with RCC. Materials and Methods: A total of 9 FDG PET/CT scans were performed in 4 patients (3 males, 1 female; median age: 53.5 years, range: 52–73 years). Of 9 PET/CT scans, 2 scans were done for initial staging, 2 for restaging, and 5 for evaluation of treatment response. PET/CT image interpretation and analysis was performed qualitatively (visually) and semiquantitatively. Absence of uptake in postchemotherapy PET/CT scan was considered as complete response and a fall in SUV by more than 50% of baseline value, as significant response. Results: Patients 1 and 2 underwent staging FDG PET/CT. Patient 1 had undergone left radical nephrectomy 13 years back for left-sided RCC. Current FDG PET/CT revealed appearance of right RCC with adrenal metastasis. PET/CT of patient 2 demonstrated right adrenal and distant metastases. PET/CT done for restaging in patient 3, revealed right adrenal and abdominal lymph nodal metastasis. In patient 4, PET/CT revealed solitary adrenal metastasis. Magnetic resonance imaging findings were consistent with adrenal metastasis in this patient. Patient 1 received sunitinib and interferon chemotherapy along with radiotherapy and showed partial response on PET/CT scans done at 6, 17, 23, and 33 months from the initial study. PET/CT of patient 3 demonstrated the progression of disease (nonresponder). Conclusion: FDG PET/CT appears to be useful for staging, treatment response evaluation, and recurrence detection in patients with RCC having adrenal metastasis.

Comparison of PET/CT with other imaging modalities in women with genital tuberculosis

To compare findings with 2‐deoxy‐2‐(18F)fluoro‐D‐glucose positron emission tomography combined with computed tomography (18F‐FDG‐PET/CT) with findings obtained using ultrasound (US), magnetic resonance imaging (MRI), and CT in patients with proven tubercular tubo‐ovarian masses.

PET/Computed Tomography in Neuroendocrine Tumor: Value to Patient Management and Survival Outcomes

PET/computed tomography evaluation of neuroendocrine tumors is gaining prominence with the availability of novel pet radiotracers, such as (18)F-DOPA and gallium 68 somatostatin peptide derivatives. These tumors have unique properties and hence the basis of use of these new radiotracers. Prominent centers worldwide have reported the usefulness of these PET tracers in diagnosis and clinical decision making. Portability of 68Ge/68Ga generators has also helped in more widespread use of these somatostatin peptide derivatives as PET radiotracers. This article reviews established and potential roles of these novel PET radiotracers in diagnosis, management, and prognosis of neuroendocrine tumors.

PET, PET/ CT, and PET/ MR Imaging Assessment of Breast Cancer

This review focuses mainly on clinical applications of PET/CT in patients with breast cancer. It discusses the role of 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) PET/CT (and FDG PET) in the diagnosis and initial staging of breast cancer, in monitoring the response of disease to chemotherapy, and in identifying metastatic and recurrent disease. In addition, it discusses the role of MR imaging and potential future hybrid modalities such as PET/MR imaging.

Glucagon augmented Tc99m-pertechnetate scintigraphy for detection of ectopic gastric mucosa in Meckel's diverticulum

The utility of Tc99m-pertechnetate scintigraphy in the diagnosis of ectopic gastric mucosa is well established, particularly, in the case of Meckel’s diverticulum, despite substantial variation in the reported sensitivity. In the present report, the role of glucagon augmented Tc99mpertechnetate scintigraphy’ for detection of ectopic gastric mucosa in a child with Meckel’s diverticulum is highlighted.