Quantitative CT Evaluation of Bone Mineral Density in the Thoracic Spine on 18F-Fluorocholine PET/CT Imaging in Patients With Primary Hyperparathyroidism.

INTRODUCTION: Measurement of bone mineral density (BMD) with quantitative CT (QCT) carries several advantages over other densitometric techniques, including superior assessment of the spine. As most QCT studies evaluated the lumbar spine, measurements of the thoracic spine are limited. We performed QCT analysis of the thoracic spine in a cohort of patients with primary hyperparathyroidism. MATERIALS AND METHODS: This study was a retrospective QCT analysis of the thoracic spine on 18F-fluorocholine PET/CT scans in patients with primary hyperparathyroidism patients between March 2018 and December 2022. Correlations between QCT-derived BMD or Hounsfield units (HU) and demographic data, laboratory parameters, results from histopathological examination after parathyroidectomy and results of DXA imaging were analyzed, when available. RESULTS: In 189 patients, mean QCT-derived BMD at the thoracic spine was 85.6 mg/cm3. Results from recent DXA were available in 122 patients. Mean thoracic QCT-derived BMD and HU were significantly correlated with DXA-derived BMD in lumbar spine, total hip and femoral neck and with the lowest T-score at DXA imaging. Only weak correlations were found with BMI or 18F-fluorocholine uptake, while no significant correlations were found with adenoma weight, PTH or calcium levels. CONCLUSION: Our study confirms correlation between QCT-derived BMD in the thoracic spine with age and DXA-derived BMD measurements within a population of patients with primary hyperparathyroidism. Establishment of reference BMD values for individual thoracic vertebrae, may allow direct osteoporosis classification on thoracic CT imaging.

Regional Collaboration and Trends in Clinical Management of Thyroid Cancer.

OBJECTIVE: This study examines the trends in the management of thyroid cancer and clinical outcomes in the Southwestern region of The Netherlands from 2010 to 2021, where a regional collaborative network has been implemented in January 2016. STUDY DESIGN: Retrospective cohort study. SETTING: This study encompasses all patients diagnosed with thyroid cancer of any subtype between January 2010 and June 2021 in 10 collaborating hospitals in the Southwestern region of The Netherlands. METHODS: The primary outcome of this study was the occurrence of postoperative complications. Secondary outcomes were trends in surgical management, centralization, and waiting times of patients with thyroid cancer. RESULTS: This study included 1186 patients with thyroid cancer. Median follow-up was 58 [interquartile range: 24-95] months. Surgery was performed in 1027 (86.6%) patients. No differences in postoperative complications, such as long-term hypoparathyroidism, permanent recurrent nerve paresis, or reoperation due to bleeding were seen over time. The percentage of patients with low-risk papillary thyroid carcinoma referred to the academic hospital decreased from 85% (n = 120/142) in 2010 to 2013 to 70% (n = 120/171) in 2014 to 2017 and 62% (n = 100/162) in 2018 to 2021 (P < .01). The percentage of patients undergoing a hemithyroidectomy alone was 9% (n = 28/323) in 2010 to 2013 and increased to 20% (n = 63/317; P < .01) in 2018 to 2021. CONCLUSION: The establishment of a regional oncological network coincided with a de-escalation of thyroid cancer treatment and centralization of complex patients and interventions. However, no differences in postoperative complications over time were observed. Determining the impact of regional oncological networks on quality of care is challenging in the absence of uniform quality indicators.

Gamma camera-specific reference standards for radioactive iodine uptake measurements.

BACKGROUND: Current guidelines of the radioiodine uptake (RAIU) test allow the use of different equipment, isotopes, activity and region-of-interest (ROI). We evaluated presence and extent of these differences in clinical practice and evaluated the effect of some of these variations on RAIU outcomes. Also, gamma camera-specific reference standards were calculated and retrospectively compared with measurements obtained during clinical RAIU tests. MATERIALS AND METHODS: First, questionnaires were sent to Dutch nuclear medicine departments requesting information about equipment usage, isotope, isotope formulation, activity and measurement techniques. Secondly, a neck phantom containing a range of activities in capsule or water-dissolved formulation was scanned. Counts were measured using automatic ROI, square box ROI or all counts in the image. Thirdly, clinical RAIU data were collected during 2015-2018 using three different gamma cameras. Reference standards for each scanner were calculated using regression analysis between reference activity and measured counts. Uptake measurements using this gamma camera-specific reference standard were compared with original measurements. RESULTS: The survey demonstrated significant differences in isotope, isotope formulation, activity, use of neck phantoms, frequency and duration of reference measurements, distance to collimator, use of background measurements and ROI delineation. The phantom study demonstrated higher counts for the water-dissolved formulation than capsules using both automatic and square box ROI. Also, higher counts were found using a square box ROI than an automatic ROI. The retrospective study showed feasibility of RAIU calculations using camera-specific reference standards and good correlation with the original RAIU measurements. CONCLUSIONS: This study demonstrated considerable technical variation in RAIU measurement in clinical practice. The phantom study demonstrated that these differences could result in differences in count measurements, potentially resulting in different dose calculations for radioactive iodine therapy. Retrospective data suggest that camera-specific reference standards may be used instead of individual reference measurements using separate activity sources, which may thus eliminate some sources of variation.

Feasibility of Left Ventricle Ejection Fraction Calculation Using Electrocardiographically Gated SPECT Acquisition of 99m Tc-HDP Bone Scintigraphy in Cardiac Amyloidosis.

ABSTRACT: We performed bone scintigraphy in 6 patients with suspected cardiac amyloidosis. To evaluate feasibility of left ventricle function analysis, we additionally performed electrocardiographically gated SPECT acquisition. The cardiac-gated SPECT data confirmed adequate tracer uptake for automatic myocardial contour determination. LVEF estimations ranged between 24% and 54%. Comparison with LVEF estimations from prior echocardiography generally showed only small differences. In one patient, the LVEF measurements from both methods seemed discordant, probably reflecting actual LVEF worsening, which was confirmed at follow-up echocardiography. Therefore, our results may suggest that cardiac-gated SPECT acquisition at bone scintigraphy can provide meaningful estimates of LVEF.

Peripheral Photopenia on Whole-Body PET/CT Imaging With 18F-FDG in Patients With Compartment Syndrome and Mesenteric Venous Thrombosis.

We present 2 cases that demonstrate photopenia in peripheral areas on whole-body PET/CT imaging with F-FDG as a sign of absent perfusion with severe short-term complications. The scan of the first patient shows photopenia in the right ankle and foot, resulting from compartment syndrome, caused by hemolytic group A streptococcus bacteremia with endocarditis and septic emboli, necessitating lower leg amputation. The scan of the second patient shows photopenia in the transverse colon, resulting from mesenteric venous thrombosis caused by polycythemia vera, leading to necrosis and perforation of the transverse colon, necessitating transverse and right hemicolectomy.

99mTc-MAG3 Renography of Intrathoracic Renal Ectopia.

We report a case of a 49-year-old woman with a rare anomaly, intrathoracic renal ectopia. Her medical history includes a surgically corrected congenital diaphragmatic hernia, which can cause late presentations of diaphragmatic hernia in adult life. The Tc-MAG3 renogram demonstrated slower emptying of the dilated pelvis of the ectopic kidney than the normal kidney. The curve confirmed a delayed Tmax, followed by a distinct decline. These features are not indicative of a complete obstruction, but can result from partial obstruction, renal dysfunction with poor response to diuresis, pelvic dilatation (such as in our patient), or a combination.

Lateral Recumbent or Prone Positioning for PET of the Urinary Bladder.

Evaluation of the urinary bladder on PET with F-FDG is hampered by accumulation of activity in the urinary bladder due to physiological excretion of F-FDG in urine. We present 2 examples that demonstrate the utility of delayed scanning in lateral recumbent or prone position to improve evaluation of the bladder by differentiating between active bladder wall lesions and intraluminal activity. Changing the body position from a supine to a lateral recumbent or prone position can result in migration of intraluminal activity due to gravitational force, whereas F-FDG uptake in bladder wall lesions will show no migration.