Nilendu Purandare

Diagnostic performance of response assessment FDG-PET/CT in patients with head and neck squamous cell carcinoma treated with high-precision definitive (chemo)radiation.

PURPOSE To prospectively assess diagnostic performance of response assessment fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients with HNSCC treated with high-precision definitive (chemo)radiation. METHODS Fifty-seven patients treated on a prospective clinical trial having post-treatment response assessment FDG-PET/CT scans were included. Clinico-pathologic findings and follow-up information was considered as reference standard. RESULTS First response assessment FDG-PET/CT was done at a median of 9 weeks (inter-quartile range 8-10 weeks) from completion of treatment. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of first response assessment FDG-PET/CT for identifying residual disease at primary site was 50%, 91.8%, 50%, 91.8%, and 86%. The corresponding figures for the neck were 62.5%, 98%, 83.3%, 94.1%, and 93%. With a median follow-up of 26 months (range 7-45 months), the 3-year loco-regional control (83.9% vs 58.3%, p=0.001) and overall survival (68.8% vs 58.3%, p=0.063) was significantly better in patients with negative response assessment scans. CONCLUSION The overall diagnostic accuracy of response assessment FDG-PET/CT is good, but its sensitivity and PPV is somewhat low, particularly for primary site. A negative response assessment FDG-PET/CT scan is highly suggestive of absence of viable disease that could be used to guide decision-making.

Therapeutic Response to Radiofrequency Ablation of Neoplastic Lesions: FDG PET/CT Findings

Ablation of neoplastic lesions by using radiofrequency energy is gaining popularity in clinical practice because of the minimally invasive nature of radiofrequency ablation (RFA). Primary and secondary tumors of the liver and lung are treated with RFA when surgery is precluded because of comorbidity. Benign bone tumors are also treated with RFA to relieve pain and prevent further tumor growth. Differentiation between postablation tissue changes and residual disease is difficult with morphologic imaging modalities such as ultrasonography, computed tomography (CT), and magnetic resonance (MR) imaging, thus limiting the use of these modalities to detection of residual disease early after RFA. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is a functional imaging modality that can be used to study the effects and efficacy of RFA. Lesions that show increased FDG uptake at PET become completely photopenic immediately after RFA, a finding that is suggestive of the completeness of ablation. Focal areas of increased FDG uptake within the ablated zone are suggestive of residual disease. Reactive tissue changes such as inflammation are depicted in the periphery of the ablated lesion and show a uniform low-grade FDG uptake, which can be differentiated from the focal, nodular intense uptake in areas of residual disease. Use of combined FDG PET/CT to detect residual disease early after RFA allows ablation to be repeated, if necessary, to obtain the maximum therapeutic benefit. Note that FDG uptake in the complications sometimes associated with RFA can be a cause of potential false-positive PET results.

Does PET–CT scan have a role prior to radical re-resection for incidental gallbladder cancer?

BACKGROUND Radical re-resection is offered to patients with non-metastatic, invasive, incidental gallbladder cancer. Data evaluating (18)F-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG PET-CT) in patients with incidental gallbladder cancer is sparse. AIM To evaluate the efficacy of integrated (18)F-FDG PET-CT in determining occult metastatic or residual local-regional disease in patients with incidental gallbladder cancer. METHODS Patients referred with incidental gallbladder cancer for radical re-resection were evaluated using multidetector computed tomography (MDCT) and PET-CT. Based on preoperative imaging, 24 out of 92 patients were found suitable for surgery. The two imaging modalities were evaluated with respect to residual and resectable disease. RESULTS In determining residual disease, MDCT had a sensitivity and positive predictive value (PPV) of 42.8%, each, while PET-CT had a sensitivity and PPV of 28.5 and 20%, respectively. In determining resectability, MDCT had a sensitivity, PPV, and accuracy of 100, 87.5, and 87.5%, respectively, as compared to PET-CT (sensitivity=100%, PPV=91.3%, accuracy=91.6%). CONCLUSIONS From our study, it appears that in patients with incidental gall bladder cancer without metastatic disease, PET-CT and MDCT seem to have roles complementing each other. PET-CT was able to detect occult metastatic or residual local-regional disease in some of these patients, and seems to be useful in the preoperative diagnostic algorithm of patients whose MDCT is normal or indicates locally advanced disease.

Integrated PET/CT in evaluating sarcomatous transformation in osteochondromas.

Aim: To study the role of PET-CT in evaluating sarcomatous transformation in osteochondromas. Materials and Methods: This was a retrospective analysis of a prospective data base of 12 patients from 2005 to 2007 with a clinical diagnosis of an osteocartilaginous lesion who were referred for a FDG PET-CT study to evaluate for possible malignant transformation. Imaging was performed on a GE Discovery ST PET-CT system after intravenous injection of 370 MBq (10 mCi) of F-18 FDG. Results: Seven patients with histopathological evidence of a sarcomatous transformation to grade II chondrosarcoma showed moderate to high FDG uptake (SUV 3.3–6.9), whereas 1 patient with a dedifferentiated chondrosarcoma showed a focus of very intense uptake (SUV 11.4). Four patients with histopathological and/or clinical or follow-up diagnosis of a benign osteocartilaginous lesion showed low grade FDG uptake (SUV 0.8–1.3). FDG uptake was also noted in an asymptomatic osteochondroma which on histopathology revealed a grade II chondrosarcoma. Conclusions: Whole body FDG PET-CT is an important adjunct to conventional morphologic imaging in evaluating suspected malignant transformation in osteochondromas. Increased glucose metabolism can help diagnose sarcomatous transformation at the suspected sites as well as detect early malignant change at clinically unsuspected sites. Moreover, its ability to detect a focus of dedifferentiation can be useful for prognostication and to plan adjuvant treatment. A small cohort limits statistically sound conclusions to be drawn from this study, however further prospective trials based on these findings can help explore the potential application of FDG PET-CT in this clinical condition.

Diffuse-type giant cell tumor of the subcutaneous thigh

Diffuse-type giant cell tumor is an extra-articular form of pigmented villonodular synovitis. The localized form of this lesion (tenosynovial giant cell tumor) is frequent, representing the most common subset arising from the synovium of a joint, bursa or tendon sheath, with 85% of cases occurring in the fingers. The less frequent diffuse-type giant cell tumors are commonly located in the periarticular soft tissues, but on rare occasions these lesions can be purely intramuscular or subcutaneous We report the case of a 26-year-old female with diffuse-type giant cell tumor of the subcutaneous thigh, remote from a joint, bursa or tendon sheath. A review of the literature did not reveal any similar description of a diffuse-type giant cell tumor completely within the subcutaneous thigh, remote from a joint, bursa or tendon sheath. These lesions were initially regarded as inflammatory or reactive processes, but since the identification of clonal abnormalities in these patients, and in view of their capacity for autonomous growth, they are now widely considered to represent benign neoplasms.

Prospective randomized controlled trial to compare 3‐dimensional conformal radiotherapy to intensity‐modulated radiotherapy in head and neck squamous cell carcinoma: Long‐term results

Grade ≥2 acute xerostomia between 3D conformal radiotherapy (RT) and intensity‐modulated radiotherapy (IMRT) was evaluated in patients with head and neck squamous cell carcinomas (HNSCCs) treated radically.

EGFR Mutations in Indian Lung Cancer Patients: Clinical Correlation and Outcome to EGFR Targeted Therapy

Screening for EGFR mutation is a key molecular test for management of lung cancer patients. Outcome of patients with mutation receiving EGFR tyrosine kinase inhibitor is known to be better across different ethnic populations. However, frequency of EGFR mutations and the clinical response in most other ethnic populations, including India, remains to be explored. We conducted a retrospective analysis of Indian lung cancer patients who were managed with oral tyrosine kinase inhibitors. Majority of the patients in the study had adenocarcinoma and were non-smokers. 39/111 patients tested positive for EGFR kinase domain mutations determined by Taqman based real time PCR. The overall response to oral TKI therapy was 30%. Patients with an activating mutation of EGFR had a response rate of 74%, while the response rate in patients with wild type EGFR was 5%, which was a statistically significant difference. Progression free survival of patients with EGFR mutations was 10 months compared to 2 months for EGFR mutation negative patients. Overall survival was 19 months for EGFR mutation patients and 13 months for mutation negative patients. This study emphasizes EGFR mutation as an important predictive marker for response to oral tyrosine kinase inhibitors in the Indian population.

18F-FDG PET/CT-directed biopsy: does it offer incremental benefit?

PurposeTo study whether the metabolic information provided by a prior PET/computed tomography (CT) scan can add valuable information and an incremental benefit while performing image-guided biopsies. MethodsFluorine-18 fluorodeoxyglucose (18F-FDG) PET/CT findings of 112 patients were available before biopsy and were considered for analysis. Biopsies were performed using standard techniques only after the needle tip was confirmed to be in the portion of the lesion corresponding to the hypermetabolic area seen on PET. This was achieved by visual coregistration and also by software registration algorithms that registered the intraprocedural CT images with the preselected PET/CT data. Only those biopsies for which a definitive histopathological diagnosis could be made were considered ‘diagnostic’. Cases in which PET/CT added an incremental value were divided into three categories. ResultsA total of 112 patients (66 male and 46 female, age range 16–74 years) underwent a biopsy based on PET findings. The biopsy sites were as follows: lung, 54; lymph nodes, 27; bone, 12; and soft-tissue masses/deposits, 19. Out of the 112 biopsies, an incremental benefit was seen overall in 53 patients (47.3%): in 40.7% (22/54) of patients who underwent lung biopsies, 44.4% (12/27) of those who underwent lymph node biopsies, 66.6% (8/12) of those who underwent bone biopsies and 57.8% (11/19) of those who underwent soft-tissue biopsies. Out of the cases that showed an incremental benefit, the highest number (30) belonged to the category in which the biopsy sample was obtained from the focal hypermetabolic portion of the apparently larger morphological lesion seen on CT. ConclusionPET/CT data coregistered with intraprocedural CT images can guide needle placement in the viable portion of the lesion, thus increasing the chances of achieving a definitive diagnosis. This approach can offer a significant incremental benefit while performing image-guided biopsies.

Isolated asymptomatic skeletal muscle metastasis in a potentially resectable non-small cell lung cancer: detection with FDG PET-CT scanning.

Abstract Asymptomatic skeletal muscle metastasis in non-small cell lung cancer is a rare event particularly when it is detected at initial staging. This report describes how whole body imaging with [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) detected a solitary asymptomatic metastasis to the gluteus maximus muscle in a potentially resectable case of non-small cell lung cancer, thereby changing the treatment plan from surgical resection to systemic chemotherapy.

90Y microsphere therapy: does 90Y PET/CT imaging obviate the need for 90Y Bremsstrahlung SPECT/CT imaging?

BackgroundTransarterial radioembolization using 90Y microspheres is a novel therapeutic option for inoperable hepatic malignancies. As these spheres are radiolucent, real-time assessment of their distribution during the infusion process under fluoroscopic guidance is not possible. Bremsstrahlung radiations arising from 90Y have conventionally been used for imaging its biodistribution. Recent studies have proved that sources of 90Y also emit positrons, which can further be used for PET/computed tomography (CT) imaging. This study aimed to assess the feasibility of 90Y PET/CT imaging in evaluating microsphere distributions and to compare its findings with those of Bremsstrahlung imaging. Materials and methodsThirty-five sessions of 90Y microsphere transarterial radioembolization were performed on 30 patients with hepatic malignancies. 90Y PET/CT imaging was performed within 3 h of therapy. Bremsstrahlung imaging was also performed for each patient. The imaging findings were compared for concordance in the distribution of microspheres. ResultsExact one-to-one correspondence between 90Y PET/CT imaging and 90Y Bremsstrahlung imaging was observed in 97.14% of cases (i.e. in 34/35 cases). Discordance was observed only in one case in which 90Y PET/CT imaging resolved the microsphere uptake in the inferior vena cava tumor thrombus, which was, however, not visualized on Bremsstrahlung imaging. ConclusionThere is good concordance in the imaging findings of 90Y PET/CT and 90Y Bremsstrahlung imaging. 90Y PET/CT imaging scores over the conventionally used Bremsstrahlung imaging in terms of better resolution, ease of technique, and comparable image acquisition time. This makes it a preferred imaging modality for assessment of the distribution of 90Y microspheres.