Kanhaiyalal Agrawal

Comparison of 18F-FDG and 68Ga DOTATATE PET/CT in localization of tumor causing oncogenic osteomalacia.

Background Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome, usually caused by small benign mesenchymal tumors. The localization of these tumors is challenging, however, essential for the management. We compared the utility of 18F-FDG PET/CT and 68Ga DOTATATE PET/CT to detect the site of primary tumor in patients with suspicion of TIO. Patients and Methods Retrospective analysis of 6 patients with hypophosphatemic osteomalacia and suspicion of TIO was performed. 68Ga DOTATATE PET/CT study was performed in all 6 patients to localize the tumor. 18F-FDG PET/CT was performed in 4 of 6 patients. 18F-FDG and 68Ga DOTATATE PET/CT studies were performed within 1 week of each other. Both studies were interpreted blindly without the knowledge of other imaging findings. Results All patients had symptoms of osteomalacia and hypophosphatemia. All except 1 patient had increased level of fibroblast growth factor 23. The lag time (symptoms to PET diagnosis) ranged from 1.5 to 22 years. In 4 patients, where both studies were performed, 18F-FDG and 68Ga DOTATATE PET/CT were able to localize the tumor in 2 and 3 patients. 68Ga DOTATATE PET/CT detected tumor in 5 (83.3%) of 6 patients. Conclusions 68Ga DOTATATE PET/CT performed better than 18F-FDG PET/CT and is useful in the detection of tumors causing oncogenic osteomalacia. Therefore, in clinically suspected cases of hypophosphatemic osteomalacia, 68Ga DOTATATE PET/CT may be performed as first-line imaging investigation to avoid delay in the treatment of this devastating but curable disease. However, further studies with large patient population are warranted to validate our data.

F-18 fluoro-deoxy-glucose and F-18 sodium fluoride cocktail PET/CT scan in patients with breast cancer having equivocal bone SPECT/CT

Introduction: Although single-photon emission computed tomography (SPECT)/computed tomography (CT) plays a major role in the characterization of equivocal lesions on bone scintigraphy, it remains equivocal in a fraction of these patients. We evaluated the additional value of cocktail F-18 sodium fluoride (18F-NaF) and F-18 fluorodeoxyglucose (18F-FDG) co-injection positron emission tomography (PET) (cocktail PET) in these patients. Materials and Methods: Fifteen breast cancer patients, who had equivocal findings on the whole body bone scan (WBS) and SPECT/CT, were subjected to a cocktail PET/CT scan. The cocktail PET/CT was performed by co-administration of 18F-FDG and 18F-NaF in a ratio of about 2.4, with the total administered activity kept at approximately 10 mCi. Results: Of the 15 patients, seven were with locally advanced breast cancer (LABC) and the other eight were referred because of suspicion of recurrent disease on follow-up. Of the seven patients with LABC, the cocktail PET scan was positive for all the lesions suspicious on WBS and SPECT/CT. Additionally, it showed uptake in the primary tumor and ipsilateral axillary lymph nodes as well as identified additional osseous, lymph nodal, and solid organ metastases in these patients. Similarly, of the eight patients studied for suspicion of recurrence, the cocktail PET scan was found to be positive in seven patients. In three patients, additional osseous lesions were noted. Conclusion: The cocktail PET/CT scan can characterize almost all the suspicious equivocal lesions on the bone scan and SPECT/CT. The distinct advantage of identifying lymph nodal and solid organ metastases allows it to be considered as a useful imaging modality in patients with equivocal bone SPECT/CT.

Single photon emission computed tomography/computed tomography of the skull in malignant otitis externa

Malignant otitis externa is a severe, rare infective condition of the external auditory canal and skull base. The diagnosis is generally made from a range of clinical, laboratory, and imaging findings. Technetium 99m methylene diphosphonate bone scintigraphy is known to detect osteomyelitis earlier than computed tomography. The authors present a patient with bilateral malignant otitis externa where the extent of skull base involvement was determined on 3-phase bone scintigraphy with single photon emission computed tomography/computed tomography.

Polycystic kidney disease: renal cyst infection detected on F-18 FDG PET/CT.

Cyst infection within a polycystic kidney is a serious complication, potentially leading to abscess, sepsis, and death. Diagnosis of renal cyst infection is usually based on positive blood cultures in the presence of fever and renal tenderness. The authors present an image that shows F-18 FDG concentration in multiple infected cysts in a patient with polycystic kidney disease, with resolution after adequate antibiotic treatment.

68Ga DOTATATE PET/CT in a rare coexistence of pituitary macroadenoma and multiple paragangliomas.

The coexistence of a pituitary neoplasm and pheochromocytoma is a rare condition, which may be another undefined variant of Multiple endocrine neoplasia (MEN) syndrome. Moreover, the coexistence of pituitary macroadenoma and multiple paragangliomas is more uncommon and only few authors have reported these findings. We are reporting the use of Ga DOTATATE PET/CT in a rare case of coexisting pituitary macroadenoma and multiple paragangliomas.

Role of single photon emission computed tomography/computed tomography in diagnostic iodine-131 scintigraphy before initial radioiodine ablation in differentiated thyroid cancer

Objectives: The study was performed to evaluate the incremental value of single photon emission computed tomography/computed tomography (SPECT/CT) over planar radioiodine imaging before radioiodine ablation in the staging, management and stratification of risk of recurrence (ROR) in differentiated thyroid cancer (DTC) patients. Materials and Methods: Totally, 83 patients (21 male, 62 female) aged 17–75 (mean 39.9) years with DTC were included consecutively in this prospective study. They underwent postthyroidectomy planar and SPECT/CT scans after oral administration of 37–114 MBq iodine-131 (I-131). The scans were interpreted as positive, negative or suspicious for tracer uptake in the thyroid bed, cervical lymph nodes and sites outside the neck. In each case, the findings on planar images were recorded first, without knowledge of SPECT/CT findings. Operative and pathological findings were used for postsurgical tumor–node–metastasis staging. The tumor staging was reassessed after each of these two scans. Results: Single photon emission computed tomography/computed tomography localized radioiodine uptake in the thyroid bed in 9/83 (10.8%) patients, neck nodes in 24/83 (28.9%) patients and distant metastases in 8/83 (9.6%) patients in addition to the planar study. Staging was changed in 8/83 (9.6%), ROR in 11/83 (13.2%) and management in 26/83 (31.3%) patients by the pretherapy SPECT/CT in comparison to planar imaging. SPECT/CT had incremental value in 32/83 patients (38.5%) over the planar scan. Conclusion: Single photon emission computed tomography/computed tomography is feasible during a diagnostic I-131 scan with a low amount of radiotracer. It improved the interpretation of pretherapy I-131 scintigraphy and changed the staging and subsequent patient management.

Differential uptake of Tc-99m DMSA and Tc-99m EC in renal tubular disorders: Report of two cases and review of the literature

Tc-99m DMSA and Tc-99m EC studies are invaluable functional imaging modalities for renal structural and functional assessment. Normally, the relative renal function estimated by the two methods correlates well with each other. We here present two patients with renal tubular acidosis who showed impaired/altered DMSA uptake with normal EC renal dynamic study depicting the pitfall of DMSA imaging in tubular disorders. The two presented cases also depict distinct pattern of Tc-99m DMSA scintigraphic findings in patients with proximal and distal renal tubular acidosis, thus highlighting the factors affecting DMSA kinetics.

FDG PET/CT in Detection of Metastatic Involvement of Heart and Treatment Monitoring in Non-Hodgkin's Lymphoma

Cardiac metastasis occurs in up to a quarter of patients with metastatic cancer and is seen most commonly in melanoma and lymphoma. Metastatic involvement of the heart and pericardium may go unrecognized until autopsy. We describe a patient of non-Hodgkins lymphoma detected to have involvement of right atrium on F-18 FDG PET/CT and monitoring of response to chemotherapy.

New axillary lymph nodal F-18 fluoro-deoxy glucose uptake in an interim positron emission tomography scan - not always a sign of disease progression

Fluoro-deoxy glucose (FDG) is a non-specific tracer and may accumulate in non-malignant conditions causing potential pitfalls leading to false-positive interpretations of interim positron emission tomography scan. We report a case of a potential pitfall of false-positive axillary lymph nodal F-18 FDG uptake caused by injection extravasation.

[18F]Fluoride and [18F]fluorodeoxyglucose PET/CT in myositis ossificans of the forearm

A 20-year-old woman presented with gradually increasing swelling of the left forearm for 3 years with accompanying pain for 2 months. There was no history of trauma to the forearm. Radiographs of the left forearm showed areas of extraosseous calcifications. Magnetic resonance imaging showed multiple nodular lesions with calcification within the muscles of the extensor compartment, suggestive of myositis ossificans (MO). The patient underwent PET/CT scans using [ 18 F]fluoride (a–c) and [ 18 F]fluorodeoxyglucose (FDG) (d–f) on 2 different days. Multiple areas of dense calcification were seen in the extensor muscles of the left forearm with intense [ 18 F]fluoride uptake in the adjacent soft tissues, indicating ongoing osteoblastic activity. FDG uptake was detected in a few of these regions, suggestive of active inflammation (myositis). Biopsy from this region confirmed the presence of extra-osseous bony fragments.