Utility of 99mTc-Sulfur Colloid Lymphoscintigraphy and SPECT/CT in Chylothorax and Chylous Ascites

Purpose

To assess the diagnostic efficacy of 99mTc-sulfur colloid lymphoscintigraphy in chylothorax and chylous ascites, and the utility of single-photon emission computed tomography-computed tomography (SPECT/CT) in localizing the sites of leaks.

Methods

Data from patients who underwent lymphoscintigraphy for clinical suspicion of chylothorax or chylous ascites were retrospectively analyzed. Biochemical fluid analysis was taken as the reference standard. Pleural fluid triglyceride level > 110 mg/dL (with pleural fluid/serum ratio > 1) and a cholesterol level < 200 mg/dL (with pleural fluid/serum ratio < 1) were considered confirmatory for chylothorax. Ascitic fluid triglyceride level > 200 mg/dL with a low cholesterol level (ascites fluid/serum ratio < 1) was considered confirmatory for chylous ascites.

Results

26 patients (15 males, 57.7%) aged 9 months to 68 years were enrolled in the study. Based on the reference standard, 17 had chylothorax or chylous ascites (9 with surgical history). Lymphoscintigraphy was positive in 16 (with 1 false positive) and negative in 10 (with 2 false negatives). The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of lymphoscintigraphy were 88.2% (63.6-98.5%), 88.9% (51.8-99.7%), 80.0% (51.6-93.8%), 93.8% (70.1-99.0%), and 88.5% (69.9-97.6%), respectively. SPECT/CT could localize sites of leaks in 61.5% (8/13) with a localization rate of 77.8% (7/9) and 25.0% (1/4) in patients with surgical and nonsurgical causes, respectively.

Conclusion

99mTc-sulfur colloid lymphoscintigraphy is a highly efficacious noninvasive modality to diagnose chylothorax or chylous ascites with a high positive predictive value. SPECT/CT could localize the sites of leaks more frequently in patients with surgical causes.

Tc-99m Glucoheptonate Single Photon Emission Computed Tomography-Computed Tomography for Detection of Recurrent Glioma: A Prospective Comparison with N-13 Ammonia Positron Emission Tomography-Computed Tomography

Purpose of the Study:

To assess the efficacies of Tc-99m glucoheptonate single photon emission computed tomography-computed tomography (Tc-99m GHA SPECT-CT) and N-13 ammonia positron emission tomography-computed tomography (N-13 NH₃ PET-CT) in detecting recurrent glioma.

Materials and Methods:

Fifty-five consecutive, histologically proven, and previously treated glioma patients (age, 38.9 ± 12.2 years; 61.8% males) presenting with clinical suspicion of recurrence were evaluated with Tc-99m GHA SPECT-CT and N-13 NH₃ PET-CT. Images were evaluated both qualitatively and semiquantitatively. A combination of clinicoradiological follow-up, repeat imaging, and/or biopsy (when available) was considered as the reference standard.

Results:

Based on the reference standard, 28/55 (50.9%) patients had recurrence. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy of Tc-99m GHA SPECT-CT, and N-13 NH₃ PET-CT were 85.7%, 85.2%, 85.7%, 85.2%, 85.5% and 78.6%, 88.9%, 88.0%, 80.0%, 83.6%, respectively (concordant findings in 46 patients). The performances of the two modalities were equivalent both in overall and subgroup McNemar analyses (P = 0.508, overall; P = 0.687, low grade; P = 1.000, high grade).

Conclusion:

Tc-99m GHA SPECT-CT is an alternative imaging modality equally efficacious as N-13 NH₃ PET-CT in detecting recurrent glioma.

Proteus syndrome: a case report with bone scintigraphy findings

Proteus syndrome is an extremely rare genetic disorder characterized by an asymmetrical overgrowth of skin, bones, muscles, fatty tissues, and blood and lymphatic vessels. We present a case of a six-year-old boy with proteus syndrome who underwent bone scintigraphy for suspected osteomyelitis. Bone scintigraphy ruled out osteomyelitis and suggested cellulitis. In addition, it demonstrated striking characteristic deformities, which need to be emphasized. Knowledge of these findings will avoid misinterpretation of bone scintigraphy in patients with proteus syndrome.

18F-FDOPA PET/CT for detection of recurrence in patients with glioma: prospective comparison with 18F-FDG PET/CT

PURPOSE

Differentiation between recurrence and radiation necrosis in patients with glioma is crucial, since the two entities have completely different management and prognosis. The purpose of the present study was to compare the efficacies of (18)F-FDG PET/CT and 3,4-dihydroxy-6-[(18)F]fluoro-phenylalanine ((18)F-FDOPA) PET/CT in detection of recurrent gliomas.

METHODS

A total of 28 patients (age 38.82 ± 1.25 years; 85.7% men) with histopathologically proven glioma with clinical/imaging suspicion of recurrence were evaluated using (18)F-FDG PET/CT and (18)F-FDOPA PET/CT. (18)F-FDG PET/CT and (18)F-FDOPA PET/CT images were evaluated qualitatively and semiquantitatively. The combination of clinical follow-up, repeat imaging and/or biopsy (when available) was taken as the reference standard.

RESULTS

Based on the reference standard, 21 patients were positive and 7 were negative for tumour recurrence. The sensitivity, specificity and accuracy of (18)F-FDG PET/CT were 47.6%, 100% and 60.7%, respectively, and those of (18)F-FDOPA PET/CT were 100%, 85.7% and 96.4%, respectively. The results of (18)F-FDG PET/CT and (18)F-FDOPA PET/CT were concordant in 57.1% of patients (16 of 28) and discordant in 42.9% (12 of 28). The difference in the findings between (18)F-FDG PET/CT and (18)F-FDOPA PET/CT was significant (P = 0.0005, McNemar's test). The difference was significant for low-grade tumours (P = 0.0039) but not for high-grade tumours (P = 0.250).

CONCLUSION

(18)F-FDOPA PET/CT is highly sensitive and specific for detection of recurrence in glioma patients. It is superior to (18)F-FDG PET/CT for this purpose and is especially advantageous in patients with low-grade gliomas.

Isolated cardiac metastasis in a patient with neuroendocrine carcinoma of pancreas discovered on ⁶⁸Ga-DOTANOC PET/CT

We present an interesting image that demonstrates utility of (68)Ga-DOTANOC PET/CT for demonstrating rare metastatic sites of neuroendocrime tumor.

Utility of (99m)Tc-MDP SPECT-CT for the diagnosis of sesamoiditis as cause of metatarsalgia

Metatarsalgia is a general term for pain in the area of the metatarsophalangeal joints. Sesamoiditis is an uncommon cause of metatarsalgia. It is pain at the sesamoid bones beneath the head of the first metatarsal with inflammation or fracture. The diagnosis is usually clinical, with localized tenderness on palpation. Diagnosing the cause of metatarsalgia in patients without this classical sign is difficult. We present here such a case of a 37-year-old lady in whom sesamoiditis was diagnosed with technetium-99m (^99mTc)-methylene diphosphonate (MDP) single photon emission tomography-computed tomography (SPECT-CT).