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.

Estimated glomerular filtration rate in children: adapting existing equations for a specific population.

BACKGROUND: Creatinine-based glomerular filtration rate (GFR)-estimating equations frequently do not perform well in populations that differ from the development populations in terms of mean GFR, age, pathology, ethnicity, and diet. After first evaluating the performance of existing equations, the aim of this study was to demonstrate the utility of an in-house modification of the equations to better fit a specific population. METHODS: Estimated GFR using 8 creatinine-based equations was first compared to 2-sample 51Cr-ethylenediaminetetra-acetic acid plasma clearance in non-cancer and cancer groups independently. The groups were then divided into development and validation sets. Using the development set data, the Microsoft® Excel SOLVER add-in was used to modify the parameters of 7 equations to better fit the data. Using the validation set data, the performance of the original and modified equations was compared. RESULTS: Two hundred fifty-six GFR measurements were performed in 160 children. GFR was overestimated in both groups (non-cancer 4.3-22.6 ml/min/1.73 m2, cancer 17.2-46.6 ml/min/1.73 m2). The root mean square error (RMSE) was 19.1-21.8 ml/min/1.73 m2 (non-cancer) and 18.6-20.8 ml/min/1.73 m2 (cancer). The P30 values were 49.1-73.0% (non-cancer) and 19.6-66.0% (cancer). Modifying the parameters of seven equations resulted in significant improvements in the P30 values in the non-cancer (65.0-85.0%) and cancer (79.6-87.8%) groups. CONCLUSIONS: Modifying the parameters of pediatric GFR estimating-equations using a simple Excel-based tool significantly improved their accuracy in both non-cancer and cancer populations. Graphical abstract.

Validation of ICD-10-CM surveillance codes for traumatic brain injury inpatient hospitalizations.

Objective: Using inpatient data from a 1,160-bed health system, we assessed the positive predictive value (PPV) of ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) codes included in a traumatic brain injury (TBI) surveillance definition proposed by the Centers for Disease Control and Prevention (CDC) in 2016. Methods: A random sample of 196 records with ICD-10-CM TBI codes was reviewed. The PPVs for the ICD-10-CM codes' ability to capture true TBI cases were calculated as the percentage of records with confirmed clinical provider-documented TBI and reported with 95% confidence intervals [95%CIs]. Results: The estimated overall PPV was 74% [67.9%, 80.1%] when the codes were listed in any diagnostic field, but 91.5% [86.2%, 96.8%] when listed as the principal diagnosis. S06 codes (intracranial injury) had an overall PPV of 80.2% [74.3%, 86.1%] and 96.9% [93.3%, 100%] when listed as the principal diagnosis. S02.0-.1 codes (vault/base skull fractures) in any position without co-existing S06 codes had a PPV of 15.8% [0%, 33.2%]. Conclusions: Intracranial injury codes (S06) in any diagnostic position had a very high estimated PPV. Further research is needed to determine the utility of other codes included in the CDC proposed definition for TBI surveillance.

HIV status does not have an impact on positron emission tomography-computed tomography (PET-CT) findings or radiotherapy treatment recommendations in patients with locally advanced cervical cancer.

INTRODUCTION: Positron emission tomography-computed tomography (PET-CT) imaging is commonly used to identify nodal involvement in locally advanced cervical carcinoma, but its appropriateness for that purpose among HIV-positive patients has rarely been studied. We analyzed PET-CT findings and subsequent treatment prescribed in patients with locally advanced cervical carcinoma in Cape Town, South Africa. METHODS: We identified a cohort of consecutive cervical carcinoma patients International Federation of Gynecology and Obstetrics (FIGO) stage IIB to IIIB at our cancer center who underwent a planning 18-fluorodeoxyglucose (18FDG) PET-CT scan from January 2015 through December 2018. Demographics, PET-CT findings, and subsequent treatment prescribed were recorded. Patients were selected for PET-CT only if they had no signs of distant disease on staging chest X-ray or abdominal ultrasound; were deemed suitable for radical chemoradiation by the multi-disciplinary team; and had normal renal function. HIV-positive patients ideally had to have been established on continuous antiviral therapy for more than 3 months and to have a CD4 cell count above 150 cells/µL. Small cell and neuroendocrine carcinoma cases were excluded from the study. Differences in demographic and clinical measures between HIV-positive and HIV-negative patients were evaluated by means of t-tests for continuous variables and χ2 tests for categorical variables. RESULTS: Over a 4 year period, 278 patients-192 HIV-negative (69.1%) and 86 HIV-positive (30.9%)-met the inclusion criteria. HIV-positive patients had a median CD4 count of 475 cells/µL (IQR 307-612 cells/µL). More than 80% of patients had pelvic nodal involvement, and more than 40% had uptake in common iliac and/or para-aortic nodes. Nodal involvement was not associated with HIV status. Fifty-four patients (19.4%) had at least one site of distant metastatic disease. Overall, 235 patients (84.5%) were upstaged following PET-CT staging scan. Upstaging was not associated with HIV status (HIV-negative 83.9% vs HIV-positive 87.2%; p=0.47). Ten patients who did not return for radiotherapy were excluded from the analysis. Following their PET-CT scan, treatment intent changed for 124 patients (46.3%): 53.6% of HIV-positive patients and 42.9% of HIV-negative patients (p=0.11). CONCLUSION: We found no differences between HIV-positive or HIV-negative patients in nodal involvement or occult metastases, and PET-CT imaging did not lead to, or justify, treatment differences between the two groups. Future studies will evaluate survival and correlation of upstaging with outcome.

Simple Anatomical Calculations Possibly As Accurate As Three-Dimensional Lobar Quantification with SPECT-CT in Predicting Lung Function after Pulmonary Resection.

The estimation of predicted postoperative (PPO) lung function is important in lung resection candidates. We utilized simple anatomical calculations and single-photon emission computed tomography combined with computed tomography (SPECT-CT) to calculate PPO in 24 consecutive patients with impaired pulmonary function who underwent lung resection. PPO values calculated by anatomical calculations and three-dimensional lobar SPECT-CT quantification both correlated well with the postoperative forced expiratory volume in 1 s, with r = 0.825, p < 0.001 and r = 0.796, p < 0.001, respectively. Both techniques fared well at predicting postoperative lung function, but our observations unexpectedly suggested that simple anatomical calculations might be equivalent to three-dimensional SPECT-CT lobar quantification.

Evaluating the Role of F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Scanning in the Staging of Patients With Stage IIIB Cervical Carcinoma and the Impact on Treatment Decisions.

OBJECTIVE: FIGO (International Federation of Gynaecology and Obstetrics) staging is currently the most widely used clinical staging system for cervical cancer; however, this staging system has many shortcomings. One of these shortcomings is that lymph nodal status, specifically the para-aortic lymph nodal status, does not get taken into account. It is known that metabolic changes occur before changes are seen on anatomical imaging, and it is therefore possible to detect metastases earlier with the help of fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). We hypothesized that by including an FDG PET/CT study as part of the staging investigations in patients with invasive cervical cancer, pretreatment staging would improve and management would change in a significant proportion of patients. METHODS/MATERIALS: Patients diagnosed with FIGO stage IIIB cervical cancer from September 2010 to December 2015 received an FDG PET/CT study as part of their staging workup. A whole-body FDG PET/CT was performed before initiation of treatment, and the results were interpreted by experienced nuclear medicine physicians and radiologists. We determined the percentage of patients in whom PET/CT changed the stage and/or altered management of the patient. RESULTS: There were 95 patients diagnosed with stage IIIB cervix cancer during the study period who received an FDG PET/CT as part of their staging workup. Eighty-eight patients were included in the final sample. Positron emission tomography/CT affected the management of 40% of patients, with 19% requiring a change in the radiation field due to identification of para-aortic nodal involvement and 21% upstaged to stage IVB. CONCLUSIONS: Fluorodeoxyglucose PET/CT is useful in assessing distant disease and evaluating nodal involvement in patients with invasive cervical cancer. Additional findings on the PET/CT that were missed by conventional imaging and clinical examination caused treatment change in a significant proportion of patients.

Resting regional brain metabolism in social anxiety disorder and the effect of moclobemide therapy.

While there is mounting evidence of abnormal reactivity of several brain regions in social anxiety disorder, and disrupted functional connectivity between these regions at rest, relatively little is known regarding resting regional neural activity in these structures, or how such activity is affected by pharmacotherapy. Using 2-deoxy-2-(F-18)fluoro-D-glucose positron emission tomography, we compared resting regional brain metabolism between SAD and healthy control groups; and in SAD participants before and after moclobemide therapy. Voxel-based analyses were confined to a predefined search volume. A second, exploratory whole-brain analysis was conducted using a more liberal statistical threshold. Fifteen SAD participants and fifteen matched controls were included in the group comparison. A subgroup of SAD participants (n = 11) was included in the therapy effect comparison. No significant clusters were identified in the primary analysis. In the exploratory analysis, the SAD group exhibited increased metabolism in left fusiform gyrus and right temporal pole. After therapy, SAD participants exhibited reductions in regional metabolism in a medial dorsal prefrontal region and increases in right caudate, right insula and left postcentral gyrus. This study adds to the limited existing work on resting regional brain activity in SAD and the effects of therapy. The negative results of our primary analysis suggest that resting regional activity differences in the disorder, and moclobemide effects on regional metabolism, if present, are small. While the outcomes of our secondary analysis should be interpreted with caution, they may contribute to formulating future hypotheses or in pooled analyses.

Resting-state fMRI and social cognition: An opportunity to connect.

Many psychiatric disorders are characterized by altered social cognition. The importance of social cognition has previously been recognized by the National Institute of Mental Health Research Domain Criteria project, in which it features as a core domain. Social task-based functional magnetic resonance imaging (fMRI) currently offers the most direct insight into how the brain processes social information; however, resting-state fMRI may be just as important in understanding the biology and network nature of social processing. Resting-state fMRI allows researchers to investigate the functional relationships between brain regions in a neutral state: so-called resting functional connectivity (RFC). There is evidence that RFC is predictive of how the brain processes information during social tasks. This is important because it shifts the focus from possibly context-dependent aberrations to context-independent aberrations in functional network architecture. Rather than being analysed in isolation, the study of resting-state brain networks shows promise in linking results of task-based fMRI results, structural connectivity, molecular imaging findings, and performance measures of social cognition-which may prove crucial in furthering our understanding of the social brain.

High resolution imaging and five-year tuberculosis contact outcomes.

Background: The evolution of tuberculosis (TB) disease during the clinical latency period remains incompletely understood. Methods: 250 HIV-uninfected, adult household contacts of rifampicin-resistant TB with a negative symptom screen underwent baseline 18F-Fluorodeoxyglucose positron emission and computed tomography (PET/CT), repeated in 112 after 5-15 months. Following South African and WHO guidelines, participants did not receive preventive therapy. All participants had intensive baseline screening with spontaneous, followed by induced, sputum sampling and were then observed for an average of 4.7 years for culture-positive disease. Baseline PET/CT abnormalities were evaluated in relation to culture-positive disease. Results: At baseline, 59 (23.6%) participants had lung PET/CT findings consistent with TB of which 29 (11.6%) were defined as Subclinical TB, and 30 (12%) Subclinical TB-inactive. A further 83 (33.2%) had other lung parenchymal abnormalities and 108 (43.2%) had normal lungs. Over 1107-person years of follow-up 14 cases of culture-positive TB were diagnosed. Six cases were detected by intensive baseline screening, all would have been missed by the South African symptom-based screening strategy and only one detected by a WHO-recommended chest X-Ray screening strategy. Those with baseline Subclinical TB lesions on PET/CT were significantly more likely to be diagnosed with culture-positive TB over the study period, compared to those with normal lung parenchyma (10/29 [34.5%] vs 2/108 [1.9%], Hazard Ratio 22.37 [4.89-102.47, p<0.001]). Conclusions: These findings challenge the latent/active TB paradigm demonstrating that subclinical disease exists up to 4 years prior to microbiological detection and/or symptom onset. There are important implications for screening and management of TB.

Alcohol-induced psychotic disorder: brain perfusion and psychopathology--before and after anti-psychotic treatment.

Alcohol-induced psychotic disorder (AIPD) also known as alcohol hallucinosis is a rare complication of alcohol abuse. The pathogenesis and treatment of AIPD are still unclear. Few prospective treatment studies are available but case reports generally suggest that anti-psychotic treatment is effective. Brain imaging changes in relation to treatment response have also not been studied except for case reports. The aim of this study was to investigate the effect of anti-psychotic treatment on psychopathology and regional cerebral blood flow (rCBF) in patients with AIPD before and after 6 weeks of treatment. Nineteen patients with AIPD were assessed by the Positive and Negative Syndrome Scale (PANSS) and single photon emission computed tomography (SPECT) before and after 6-weeks of open-label treatment with a fixed dose of haloperidol (5 mg/day). Highly significant improvements were noted on the positive, general and total scores of the PANSS. Post-treatment increased rCBF to the left caudate and left frontal lobe was noted. Changes in frontal, temporal, parietal, occipital, thalamic and cerebellar rCBF showed significant negative correlations with the degree of symptom improvement, suggesting dysfunction of these areas in AIPD. Psychopathological and rCBF findings suggest reversible generalised cerebral dysfunction in AIPD.

Measurement of Glomerular Filtration Rate.

Glomerular filtration rate (GFR) can be estimated from the plasma concentration of endogenous substances such as creatinine, and it is simple and cost-effective to do so, but the error on these estimates on an individual patient basis is high. Thus, GFR measurement is indicated in any clinical situation in which greater accuracy is required especially if the result will impact treatment decisions. Outside of the United States the radiopharmaceutical that has been most commonly used for measurement of GFR is 51Cr-EDTA. However, due to a recent reduction in supply, there has been a shift to 99mTc-DTPA. The differences in clearance between these two tracers are small, and their clearance is comparable to the non-radiopharmaceutical markers inulin, iohexol and iothalamate. A few PET GFR tracers are currently under investigation for clinical use. Measurement of the urinary clearance of a tracer is the historical gold standard technique, however this method is prone to error due to difficulties with urine collection and inaccuracies associated with measuring residual activity in the bladder and renal drainage systems. Plasma clearance techniques provide a more practical and robust alternative and have good precision despite overestimating GFR slightly. Measurement of the area under the full plasma clearance curve is the reference method but due to the large number of blood samples required, it is largely limited to research settings. The slope-intercept and single-sample methods are simpler yet accurate alternatives that can be used in most patients. However, in patients with expanded third spaces or very low GFR (<25 mL/min/1.73 m2), different calculation methods are used that require blood sampling up to 24 hours. Camera-based methods are currently not recommended due to their imprecision. For the purposes of interpreting a GFR result, reliable reference data is available for adults and children, mostly derived from 51Cr-EDTA clearance measurements, but applicable to 99mTc-DTPA GFR. GFR has notable biological variation and is susceptible to measurement errors, the combination of which translates into a high coefficient of variation for repeat measurements. Consequently, when serial measurements are performed, large changes (>20%) are required before a change can be regarded as significant. While biological variation is largely fixed, measurement errors can be minimized through careful work in combination with a system of thorough quality control checks.

PET-CT in brain disorders: The South African context.

Positron emission tomography combined with X-ray computed tomography (PET-CT) has an established role in the management of brain disorders, but may be underutilised in South Africa. Possible barriers to access include the limited number of PET-CT facilities and the lack of contemporary guidelines for the use of brain PET-CT in South Africa. The current review aims to highlight the evidence-based usage of brain Positron emission tomography (PET) in dementia, movement disorders, brain tumours, epilepsy, neuropsychiatric lupus, immune-mediated encephalitides, and brain infections. While being areas of research, there is currently no clinical role for the use of PET-CT in traumatic brain injury or in psychiatric or neurodevelopmental disorders. Strategies to expand the appropriate use of PET-CT in brain disorders are discussed in this article.

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.

Association of Prehospital Step 1 Vital Sign Criteria and Vital Sign Decline with Increased Emergency Department and Hospital Death.

BACKGROUND: This study analyzed data from the 2017 American College of Surgeons National Trauma Data Bank to examine the effects of pre-hospital Field Triage Decision Scheme Step 1 vital sign criteria (S1C) and vital sign decline on subsequent emergency department (ED) and hospital death in emergency medical services (EMS) transported trauma victims. STUDY DESIGN: Patient and injury characteristics, transport time, and ED and hospital disposition were collected. S1C (respiratory rate [RR]<10, RR>29 breaths/min, systolic blood pressure [SBP]<90 mmHg, Glasgow Coma Scale [GCS]<14) were recorded at the injury scene and hospital arrival. Decline was defined as a change ≥ 1 standard deviation (SD) into or within an S1C range. S1C and decline were analyzed relative to ED and hospital death using logistic regression. RESULTS: Of 333,213 included patients, 54,849 (16.5%) met Step 1 criteria at the scene, and 21,566 (6.9%) declined en route. The ED death rate was 0.4% (n = 1,188), and the hospital death/hospice rate was 4.0% (11,624 of 287,675). Patients who met S1C at the scene or who declined were more likely to require longer hospital lengths of stay, ICU admission, and surgical intervention. S1C and decline patients had higher odds of death in both the ED (S1C odds ratio [OR] 15.1, decline OR 2.4, p values < 0.001) and hospital (S1C OR 4.8, decline OR 2.0, p values < 0.001) after adjusting for patient demographics, transport time and mode, injury severity, and injury mechanism. Each S1C and decline measure was independently predictive of death. CONCLUSIONS: This study quantifies the mortality risks associated with individual S1C and validates their use as an indicator for injury severity and pre-hospital triage tool.

Biomarkers to predict FDG PET/CT activity after the standard duration of treatment for spinal tuberculosis: An exploratory study.

OBJECTIVES: 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography- Computed Tomography (PET/CT) scans can be used to assess healing following treatment for spinal tuberculosis (TB) but have limited accessibility and high cost. This study investigated the association between immune biomarkers and FDG-PET/CT activity after ≥9 months of treatment for spinal TB. METHODS: Patients who had completed ≥9 months of treatment for spinal TB were recruited from a major hospital in the Western Cape, South Africa. Participants underwent a FDG-PET/CT scan and FDG- PET/CT activity was quantified for all spinal and extra-spinal sites. Participants also provided a blood sample, which was evaluated for 19 cytokines along with erythrocyte sedimentation rate (ESR). Correlations and multiple regression analyses were used to investigate the association between biomarkers and PET/CT measures. RESULTS: Twenty-eight patients were recruited, of whom 24 (86%) had spinal and/or extra-spinal FDG-PET/CT activity. In the strongest multiple regression model, CXCL10/IP-10, VEGFA, IFN-γ, CRP and Factor D/Adipsin explained 52% of the variation in overall maximal FDG uptake. Conventional monitoring marker ESR showed no significant association with PET/CT measures. CONCLUSIONS: The current findings offered encouragement that biomarkers to predict FDG-PET/CT activity may show some promise and identified candidate biomarkers for further investigation in this regard.

Kinetic modelling in small animal imaging with PET.

Small animal imaging with positron emission tomography has undergone a major evolution. This has been driven by technical improvements and the development of dedicated PET camera's for small animals. The focus has shifted from detection of tracer uptake and visualization of the tracer distribution towards the quantification of the physiological parameters necessary to use this technique for kinetic modelling of tracers. At the moment there are still several issues which need further research and evaluation before we can fully employ the possibilities of PET as an in-vivo measurement of underlying molecular biology. These issues relate to improved quantification of measurements, improved image reconstruction and processing, and the use of blood plasma data in combination with kinetic models. Besides the more technical issues, there are two more issues which need further clarification: the effect of the anaesthesia, and the effect of radiation on the experiment itself. In this review, we will give an overview of how the technique can be used but we will also discuss the issues mentioned above. The focus will be on the three major parts of the imaging procedure: acquisition, reconstruction of images, and kinetic modelling of the data.

Changes in regional brain volumes in social anxiety disorder following 12 weeks of treatment with escitalopram.

It has been suggested that antidepressants, including the selective serotonin reuptake inhibitors have neurotrophic effects. Nevertheless, the impact of treatment with a selective serotonin re-uptake inhibitor on regional brain volumes in social anxiety disorder has not been studied. 11 subjects with social anxiety disorder completed magnetic resonance imaging both before and after 12-weeks of treatment with 20 mg/day escitalopram. No increases in structural grey matter were found, but there were decreases in bilateral superior temporal cortex, vermis and the left cerebellum volumes following 12 weeks of treatment with escitalopram. These preliminary findings require replication to determine their reliability, and extension to determine whether or not they are disorder specific.

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.