Role of four-dimensional computer tomography (4D-CT) in non-localising and discordant first-line imaging in primary hyperparathyroidism.

BACKGROUND: Accurate preoperative localisation of parathyroid adenoma is imperative for the success of minimally invasive parathyroidectomy (MIP). OBJECTIVE: Our study aimed to evaluate the role of four-dimensional computer tomography (4D-CT) scan as an imaging modality in patients with failed and discordant localisation reported in the first-line imaging modalities (ultrasonography and 99mTc-MIBI-SPECT/CT). METHODS: This is a prospective cohort study performed at a university teaching centre from March 2013 to July 2021. All patients with primary hyperparathyroidism who had failed localisation by ultrasonography and 99mTc-MIBI-SPECT/CT (SpCT), or discordance between them, had 4D-CT performed in this study. RESULTS: One hundred and two sporadic cases of pHPT with failed/discordant first-line imaging had 4D-CT imaging prior to parathyroidectomy. In 102 patients, 105 parathyroid adenomas were reported on histopathology. 4D-CT was able to localise 78% of them to the correct side and 64% to the correct quadrant in 102 patients, as compared with US (correct side 21%, correct quadrant 16%) and 99mTc-MIBI-SPECT/CT (correct side 36%, correct quadrant 31%). 4D-CT had a sensitivity, precision, accuracy and F1 score for correct quadrant localisation as 79%, 81%, 66% and 80%; and for correct side localisation as 82%, 98%, 80% and 89%, respectively. 4D-CT was able to identify three ectopic adenomas (two in superior mediastinum and one in the oesophageal wall) which were not detected on US or SpCT. CONCLUSION: 4D-CT was found to be sensitive and accurate in preoperative localising of the diseased parathyroid glands after failed/discordant US and SpCT. This led to more patients being offered MIP as the primary surgery and improved operative outcomes.

Spinal CSF-Venous Fistulas in Morbidly and Super Obese Patients with Spontaneous Intracranial Hypotension.

BACKGROUND AND PURPOSE: Spinal CSF-venous fistulas are increasingly recognized as the cause of spontaneous intracranial hypotension. Here, we describe the challenges in the care of patients with CSF-venous fistulas who are morbidly or super obese. MATERIALS AND METHODS: A review was undertaken of all patients with spontaneous intracranial hypotension and a body mass index of >40 who underwent digital subtraction myelography in the lateral decubitus position to look for CSF-venous fistulas. RESULTS: Eight patients with spontaneous intracranial hypotension with a body mass index of >40 underwent lateral decubitus digital subtraction myelography. The mean age of these 5 women and 3 men was 53 years (range, 45 to 68 years). Six patients were morbidly obese (body mass indexes = 40.2, 40.6, 41, 41.8, 45.4, and 46.9), and 2 were super obese (body mass indexes = 53.7 and 56.3). Lumbar puncture showed an elevated opening pressure in 5 patients (26.5-47 cm H2O). The combination of an elevated opening pressure and normal conventional spine imaging findings resulted in a misdiagnosis (midbrain glioma and demyelinating disease, respectively) in 2 patients. Prior treatment included surgical nerve root ligation for suspected CSF-venous fistula in 3 patients. Digital subtraction myelography demonstrated a CSF-venous fistula in 6 patients (75%). Rebound high-pressure headache occurred in all 6 patients following surgical ligation of the fistula, and papilledema developed in 3. CONCLUSIONS: In our series, opening pressure was generally elevated in patients with morbid or super obesity. The yield of identifying CSF-venous fistulas with digital subtraction myelography in this patient population can approach that of the nonobese patient population. These patients may be at higher risk of developing rebound high-pressure headaches and papilledema.