Role of F-18 FDG PET-CT in neuropsychiatric systemic lupus erythematosus.

BACKGROUND: Neuropsychiatric systemic lupus erythematosus (NPSLE) is a major contributor to morbidity and mortality in systemic lupus erythematosus (SLE) patients. To date no single clinical, laboratory or imaging test has proven accurate for NPSLE diagnosis which is a testament to the intricate and multifactorial pathophysiological mechanisms suspected to exist. Functional imaging with FDG PET-CT has shown promise in NPSLE diagnosis, detecting abnormalities prior to changes evident on anatomical imaging. Research indicates that NPSLE may be more aggressive in people of African descent with higher mortality rates, making rapid and correct diagnosis even more important in the African context. METHODS: In this narrative review, we provide a thorough appraisal of the current literature on the role of FDG PET-CT in NPSLE. Large, well-known databases were searched using appropriate search terms. Manual searches of references of retrieved literature were also included. FINDINGS: A total of 73 article abstracts were assessed, yielding 26 papers that were directly relevant to the topic of FDG PET-CT in NPSLE. Results suggest that FDG PET-CT is a sensitive imaging test for NPSLE diagnosis and may play a role in assessing treatment response. It is complementary to routine anatomical imaging, particularly in diffuse manifestations of the disease. Newer quantitative analyses are commonly used for interpretation and can detect even subtle abnormalities, missed on visual inspection. Findings of group-wise analyses of FDG PET-CT scans in NPSLE patients are important in furthering our understanding of the complicated pathophysiological mechanisms involved. Limitations of FDG PET-CT include its lack of specificity, high cost and poor access. CONCLUSION: FDG PET-CT is a sensitive test for NPSLE diagnosis but is hampered by lack of specificity. It is a valuable tool for clinicians managing SLE patients, particularly when anatomical imaging is negative. Its exact application will depend on the local context and clinical scenario.

Combined versus subtraction-only technique in parathyroid scintigraphy: effect on scan interpretation.

INTRODUCTION: Parathyroidectomy is the choice of treatment for patients with primary and tertiary hyperparathyroidism. Scintigraphic, preoperative localization of hyperfunctioning parathyroid tissue depends on either a delayed washout technique, a subtraction technique, or a combination of the two. The rationale for adopting a combination approach is its presumed superior sensitivity, but there is limited evidence to support this strategy at the cost of patient inconvenience and impact on departmental workflows. OBJECTIVE: To determine whether a combined technique detects any additional lesions during scan interpretation compared to using subtraction-only technique in patients undergoing parathyroid scintigraphy before surgery. METHODS: A retrospective analysis was performed of parathyroid scans at Tygerberg Hospital between January 2012 and April 2018. Scans were reinterpreted by consensus by three readers, blinded to the original interpretation. A McNemar discordant pairs analysis was then performed. RESULTS: A total of 97 participant scans were reviewed (female: 71; mean age: 50.8 years). The number of patients with primary, secondary, and tertiary hyperparathyroidism were 63, 21, and 13, respectively. A total of 192 lesions were identified in this study. While both combined and subtraction-only approaches identified hyperfunctioning parathyroid lesions, only four lesions were identified using the combined technique that were missed by the subtraction technique. This result was not statistically significant (P = 0.125). CONCLUSION: Based on our findings, the combined parathyroid scintigraphic technique does not improve lesion detection and may be dispensed with. Doing so will enhance patient convenience and comfort and improve departmental workflows without compromising lesion detection.