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.

Repeatability of glomerular filtration rate studies performed using 99mTc-DTPA in a population including cancer patients.

OBJECTIVE: Glomerular filtration rate (GFR) measurement remains an integral investigation in clinical practice and is particularly important in the prediction and follow-up of renal side-effects of nephrotoxic chemotherapy in cancer patients. Knowing the coefficient of variation (CV) of a test is vital for the correct interpretation of serial studies. Recent difficulties with 51Cr-EDTA availability have renewed interest in 99mTc-DTPA, but there is a paucity of data on the test-retest variability of this radiopharmaceutical. Furthermore, the authors are unaware of published repeatability data in cancer patients. The aim of this study was to determine the CV of repeat 99mTc-DTPA GFR measurements in a clinical patient population that included cancer patients. METHODS: Patients who had undergone ≥2 GFR studies at our department between January 2009 and December 2019 were retrospectively identified. Patients with chronic kidney disease and those who had received chemotherapy, radiotherapy or surgery between measurements were excluded. The CV for each patient was calculated and the mean CVs of cancer and prospective renal donor groups were calculated and compared. RESULTS: Fifty-four patients were included in the final analysis. The mean CV in the cancer group (38 patients) was 8.5% [95% confidence interval (CI) 6.9-10.2%] and in the renal donor group (16 patients) 7.1% (95% CI 4.2-10.1%). These figures did not differ significantly (P = 0.37). The groups were combined to calculate the final overall mean CV of 8.1% (95% CI 6.7-9.6%). CONCLUSION: In both non-cancer and cancer patients the CV of GFR studies performed with 99mTc-DTPA was comparable with mostly 51Cr-EDTA figures presented in literature.