CT Perfusion collateral index in assessment of collaterals in acute ischemic stroke with delayed presentation: Comparison to single phase CTA.

BACKGROUND & PURPOSE: Perfusion collateral index (PCI) has been recently defined as a promising measure of collateral status. We sought to compare collateral status assessed via CT-PCI in comparison to single-phase CTA and their relationship to outcome measures including final infarction volume, final recanalization status and functional outcome in ELVO patients. METHODS: ELVO patients with anterior circulation large vessel occlusion who had baseline CTA and CT perfusion and underwent endovascular treatment were included. Collateral status was assessed on CTA. PCI from CT perfusion was calculated in each patient and an optimal threshold to separate good vs insufficient collaterals was identified using DSA as reference. The collateral status determined by CTA and PCI were assessed against 3 measured outcomes: 1) final infarction volume; 2) final recanalization status defined by TICI scores; 3) functional outcome measured by 90-day mRS. RESULTS: A total of 53 patients met inclusion criteria. Excellent recanalization defined by TICI ≥2C was achieved in 36 (68%) patients and 23 patients (43%) had good functional outcome (mRS ≤2). While having good collaterals on both CTA and CTP-PCI was associated with significantly (p<0.05) smaller final infarction volume, only good collaterals status determined by CTP-PCI was associated with achieving excellent recanalization (p = 0.001) and good functional outcome (p = 0.003). CONCLUSION: CTP-based PCI outperforms CTA collateral scores in determination of excellent recanalization and good functional outcome and may be a promising imaging marker of collateral status in patients with delayed presentation of AIS.

Tumor T2 signal intensity and stalk angulation correlates with endocrine status in pituitary adenoma patients: a quantitative 7 tesla MRI study.

PURPOSE: Pituitary adenomas are common CNS tumors that can cause endocrine dysfunction due to hormone oversecretion and by mass effect on the normal gland. The study of pituitary adenomas and adjacent sellar anatomy with high-resolution 7 T MRI may further characterize endocrine dysfunction. The purpose of this study was to determine the efficacy of 7 T MRI in identifying radiological markers for endocrine function. METHODS: MR images obtained in 23 patients with pituitary adenomas were reviewed by consensus between three neuroradiologists. Landmarks and criteria were devised to measure radiological features of stalk, tumor, and normal gland. Fischer's exact tests and nominal logistic regression were performed. RESULTS: Mean cross-sectional area of the stalk just below the infundibular recess was 6.3 ± 3.7 mm2. Mean curvature and deviation angles were 34.2° ± 23.2° and 29.7° ± 17.3°, respectively. Knosp scores obtained differed between 7 T and lower field strength scans (P < 0.0001 [right] and P = 0.0006 [left]). Ability to characterize tumor was rated higher at 7 T compared with lower field MRI, P = 0.05. Confidence in visualizing normal gland was also higher using 7 T MRI, P = 0.036. The six hormone-secreting tumors had higher corrected T2 mean SI than non-secreting tumors (2.54 vs. - 0.38, P = 0.0196). Seven patients had preoperative hypopituitarism and had significantly greater stalk curvature angles than patients without hypopituitarism (71.7° vs. 36.55°, P = 0.027). CONCLUSION: Radiological characterization of pituitary adenomas and adjacent native pituitary tissue may benefit with the use of 7 T MRI. Corrected T2 SI of tumor may be a sensitive predictor of hormonal secretion and may be useful in the diagnostic work-up for pituitary adenoma. 7 T MRI may be valuable in identifying markers of endocrine function in patients with pituitary adenomas. Our results indicate that hormone-secreting tumors have higher T2-weighted SI and tumors associated with preoperative hypopituitarism have greater stalk curvature angles.

Contrast-Enhanced Dixon Fat-Water Separation Imaging of the Spine: Added Value of Fat, In-Phase and Opposed-Phase Imaging in Marrow Lesion Detection.

OBJECTIVE: Beyond fat suppression (FS), the efficacy of (fat-water separation or Dixon [FWD]) Dixon imaging in gadolinium-enhanced spine imaging has yet to be validated. This study evaluated enhanced opposed-phase (OP) and fat-only (FO) images along with water-only (WO; FS) images against traditional unenhanced techniques and rated the incremental value of in-phase imaging in patients with presumed neoplastic focal spine lesions. METHODS: A retrospective cohort study of 36 subjects with focal spine lesions imaged with FWD was evaluated qualitatively and quantitatively. RESULTS: Enhanced OP, WO, and FO images were of significant value in detection of osseous lesions, surpassing the lesion conspicuity with conventional techniques both qualitatively and quantitatively, although the impact of in-phase imaging was limited. Water-only imaging performed well for FS. CONCLUSIONS: Contrast-enhanced FO, WO, and OP outperform traditional techniques, providing reliable lesion characterization and highest conspicuity. In-phase imaging offered limited impact on the subjective assessment of enhancement. The added value and robustness of FWD, particularly the unique contrast provided by FO imaging, suggests consideration for routine use for postgadolinium spine imaging.

Three-Tesla imaging of the pituitary and parasellar region: T1-weighted 3-dimensional fast spin echo cube outperforms conventional 2-dimensional magnetic resonance imaging.

OBJECTIVE: We explored how a novel T1-weighted 3-dimensional (3D) fast spin echo (FSE) sequence (Cube; GE, Waukesha, Wis) might outperform conventional 2-dimensional (2D) FSE techniques for contrast-enhanced imaging of the pituitary and parasellar region. METHODS: Ninety-one patients were imaged with 3D Cube and conventional 2D FSE on a 3.0-T magnetic resonance scanner. Two neuroradiologists independently assessed images for anatomical delineation (infundibulum, optic apparatus, and cavernous sinus), degree of artifact, and confidence in lesion definition or exclusion using a 5-point scale. In addition, the readers were asked to rank overall preference. RESULTS: Readers A and B found 3D Cube to be better or equal to 2D FSE in 84% and 86% of the cases. Three-dimensional Cube provided significantly better images than 2D FSE with respect to delineation of the infundibulum (P < 0.0001), cavernous sinus (P < 0.0001), optic apparatus (P = 0.002 for reader A and P = 0.265 for reader B), and fewer artifacts at the sellar floor (P < 0.0001). Three-dimensional Cube provided greater lesion conspicuity or confidence in lesion exclusion (P < 0.0001). CONCLUSIONS: Three-dimensional Cube provides superior quality with thinner slices as well as diminished artifact and can replace conventional 2D FSE sequences for routine evaluations of the pituitary and parasellar region.

Diffusion Weighted Imaging in Spine Tumors.

Diffusion weighted imaging (DWI) has developed into a powerful tool for the evaluation of spine tumors, particularly for the assessment of vertebral marrow lesions and intramedullary tumors. Advances in magnetic resonance techniques have improved the quality of spine DWI and diffusion tensor imaging (DTI) in recent years, with increased reproducibility and utilization. DTI, with quantitative parameters such as fractional anisotropy and qualitative visual assessment of nerve fiber tracts, can play a valuable role in the evaluation and surgical planning of spinal cord tumors. These widely available techniques can be used to enhance the diagnostic evaluation of spinal tumors.

Neuroimaging findings and neurological manifestations in hospitalized COVID-19 patients: Impact of cancer and ventilatory support status.

INTRODUCTION: Coronavirus 2019 (COVID-19) is known to affect the central nervous system. Neurologic morbidity associated with COVID-19 is commonly attributed to sequelae of some combination of thrombotic and inflammatory processes. The aim of this retrospective observational study was to evaluate neuroimaging findings in hospitalized COVID-19 patients with neurological manifestations in cancer versus non-cancer patients, and in patients with versus without ventilatory support (with ventilatory support defined as including patients with intubation and noninvasive ventilation). Cancer patients are frequently in an immunocompromised or prothrombotic state with side effects from chemotherapy and radiation that may cause neurological issues and increase vulnerability to systemic illness. We wanted to determine whether neurological and/or neuroimaging findings differed between patients with and without cancer. METHODS: Eighty adults (44 male, 36 female, 64.5 ±14 years) hospitalized in the Mount Sinai Health System in New York City between March 2020 and April 2021 with reverse-transcriptase polymerase chain reaction-confirmed COVID-19 underwent magnetic resonance imaging (MRI) during their admissions. The cohort consisted of four equal subgroups based on cancer and ventilatory support status. Clinical and imaging data were acquired and analyzed. RESULTS: Neuroimaging findings included non-ischemic parenchymal T2/FLAIR signal hyperintensities (36.3%), acute/subacute infarcts (26.3%), chronic infarcts (25.0%), microhemorrhages (23.8%), chronic macrohemorrhages (10.0%), acute macrohemorrhages (7.5%), and encephalitis-like findings (7.5%). There were no significant differences in neuroimaging findings between cancer and non-cancer subgroups. Clinical neurological manifestations varied. The most common was encephalopathy (77.5%), followed by impaired responsiveness/coma (38.8%) and stroke (26.3%). There were significant differences between patients with versus without ventilatory support. Encephalopathy and impaired responsiveness/coma were more prevalent in patients with ventilatory support (p = 0.02). Focal weakness was more frequently seen in patients without ventilatory support (p = 0.01). DISCUSSION: This study suggests COVID-19 is associated with neurological manifestations that may be visible with brain imaging techniques such as MRI. In our COVID-19 cohort, there was no association between cancer status and neuroimaging findings. Future studies might include more prospectively enrolled systematically characterized patients, allowing for more rigorous statistical analysis.

Trans-synaptic degeneration of the optic radiation from optic nerve atrophy.

Fourty-seven-year-old woman with 5-year history of progressive decreased left eye vision. Optical coherence tomography showed optic nerve atrophy (left > right) and brain MRI revealed T2 hyperintense signal along the course of left optic radiations. We present a case of a trans-synaptic degeneration of the optic radiation in a patient with confirmed optic atrophy. Trans-synaptic degeneration of the optic radiation without associated infarct or inflammatory disease has not been reported before in patients with optic atrophy.

Prospective Motion Correction for Brain MRI Using an External Tracking System.

BACKGROUND AND PURPOSE: A wide range of strategies have been developed to mitigate motion, as a major source of image quality degradation in clinical MRI. We aimed to assess the efficiency of a commercially available prospective motion correction (PMC) system in reducing motion in acquiring high-resolution 3D magnetization-prepared rapid gradient-echo (MPRAGE). METHODS: A total of 100 patients who referred for brain MRI studies were prospectively imaged using a 3.0T scanner. 3D MPRAGE acquisition was obtained with and without application of PMC. The motion tracking system (KinetiCor Inc.) consisted of a quad camera apparatus, which tracks a specific marker on patient's head by evaluating the marker's optical pattern. The patient's head motion in 6 degrees of freedom throughout the acquisition was then incorporated into the MRI sequence, updating the image acquisition in real time based on the most recent head pose data. MPRAGE images with and without motion correction were assessed independently by two board-certified neuroradiologists using a 5-point Likert scale. Statistical analysis included kappa and Wilcoxon Rank-Sum tests. RESULTS: Observers 1 and 2 identified nondiagnostic studies in 17.2% and 20.7% of patients (K = .78, 95% CI .70-.86) without motion correction and in 5.7% and 8% of the studies with motion correction (K = .84, 95% CI .76-.92). The number of nondiagnostic studies was significantly (P = .001) reduced from 19.5% to 5.7% after motion correction in consensus read analysis. CONCLUSION: The described motion tracking system can be used effectively in clinical practice reducing motion artifact and improving image quality of 3D MPRAGE sequence.

Neurovascular complications that can be seen in COVID-19 patients.

Coronavirus disease 2019 (COVID-19), a clinical manifestation of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was declared a global pandemic by the World Health Organization on March 11, 2020. Hypercoagulable state has been described as one of the hallmarks of SARS-CoV-2 infection and has been reported to manifest as pulmonary embolisms, deep vein thrombosis, and arterial thrombosis of the abdominal small vessels. Here we present cases of arterial and venous thrombosis pertaining to the head and neck in COVID-19 patients.

Addition of arterial spin-labelled MR perfusion to conventional brain MRI: clinical experience in a retrospective cohort study.

OBJECTIVE: The usage of arterial spin labelling (ASL) perfusion has exponentially increased due to improved and faster acquisition time and ease of postprocessing. We aimed to report potential additional findings obtained by adding ASL to routine unenhanced brain MRI for patients being scanned in a hospital setting for various neurological indications. DESIGN: Retrospective. SETTING: Large tertiary hospital. PARTICIPANTS: 676 patients. PRIMARY OUTCOME: Additional findings from ASL sequence compared with conventional MRI. RESULTS: Our patient cohorts consisted of 676 patients with 257 with acute infarcts and 419 without an infarct. Additional findings from ASL were observed in 13.9% (94/676) of patients. In the non-infarct group, additional findings from ASL were observed in 7.4% (31/419) of patients, whereas in patients with an acute infarct, supplemental information was obtained in 24.5% (63/257) of patients. CONCLUSION: The addition of an ASL sequence to routine brain MRI in a hospital setting provides additional findings compared with conventional brain MRI in about 7.4% of patients with additional supplementary information in 24.5% of patients with acute infarct.

CLINICALLY SILENT ADRENOCORTICOTROPIC HORMONE-SECRETING CROOKE CELL ADENOMA PRESENTING AS UNILATERAL EAR PAIN.

OBJECTIVE: Crooke cell adenoma (CCA) is a rare tumor of the anterior pituitary. It is highly aggressive and carries significant risk of morbidity and mortality. METHODS: This report focuses on the presentation of this disease process and review diagnosis and treatment. The patient is a 64-year-old male with a history of resected pituitary adenoma of unknown pathology. RESULTS: The patient underwent serial magnetic resonance imaging surveillance for numerous years without recurrence of tumor, however eventually developed symptoms of worsening left ear pain over 3 weeks that rapidly evolved to include ptosis. Imaging revealed a new pituitary macroadenoma. Urgent surgical resection revealed histopathological diagnosis of CCA. Corticotroph adenomas represent a rare subset of pituitary tumors. Clinically silent pituitary tumors demonstrate relatively higher rates of cavernous sinus invasion (30% versus 18%) and progression or recurrence (34% versus 6%) when compared to nonfunctioning adenomas. In CCA, only 65% of patients have clinical features of Cushing disease at presentation. Twenty-four-hour urinary free cortisol is discussed in the literature as a potential tool, where a value 4 times the upper limit of normal was predictive of higher risk of having Crooke cell changes. With a recurrence rate of up to 60%, multimodal treatment (surgery and radiation) is preferred. CONCLUSION: This case highlights early detection and treatment as keys to reducing the risk of morbidity and mortality from CCA. Currently, there are limited tools for identifying patients who are high risk for developing Crooke cell changes. Treatment modalities classically include surgery and radiotherapy. Adjuvant and novel chemotherapies are being explored.

7T MRI in epilepsy patients with previously normal clinical MRI exams compared against healthy controls.

OBJECTIVE: To compare by 7 Tesla (7T) magnetic resonance imaging (MRI) in patients with focal epilepsy who have non-lesional clinical MRI scans with healthy controls. METHODS: 37 patients with focal epilepsy, based on clinical and electroencephalogram (EEG) data, with non-lesional MRIs at clinical field strengths and 21 healthy controls were recruited for the 7T imaging study. The MRI protocol consisted of high resolution T1-weighted, T2-weighted and susceptibility weighted imaging sequences of the entire cortex. The images were read by two neuroradiologists, who were initially blind to clinical data, and then reviewed a second time with knowledge of the seizure onset zone. RESULTS: A total of 25 patients had findings with epileptogenic potential. In five patients these were definitely related to their epilepsy, confirmed through surgical intervention, in three they co-localized to the suspected seizure onset zone and likely caused the seizures. In seven patients the imaging findings co-localized to the suspected seizure onset zone but were not the definitive cause, and ten had cortical lesions with epileptogenic potential that did not localize to the suspected seizure onset zone. There were multiple other findings of uncertain significance found in both epilepsy patients and healthy controls. The susceptibility weighted imaging sequence was instrumental in guiding more targeted inspection of the other structural images and aiding in the identification of cortical lesions. SIGNIFICANCE: Information revealed by the improved resolution and enhanced contrast provided by 7T imaging is valuable in noninvasive identification of lesions in epilepsy patients who are non-lesional at clinical field strengths.

Cerebral Radiation Necrosis: An Analysis of Clinical and Quantitative Imaging and Volumetric Features.

BACKGROUND: Radiation therapy is an effective treatment for primary brain tumors and intracranial metastases but can occasionally precede new enhancing lesions on imaging studies that are difficult to discern between tumor recurrence (TR) and radiation necrosis (RN). The aim of this study was to identify clinical presentation and imaging patterns of RN compared with TR that may obviate the need for invasive definitive biopsy. METHODS: Patients who received radiation therapy and subsequently presented with a new intracranial lesion were reviewed from 2001 to 2016; 27 patients were identified with adequate records and confirmed pathology to have RN present or TR only. Patient and lesion characteristics were assessed using univariate and multivariate logistic regression analyses. Sensitivity and specificities were calculated for imaging features and quantitatively segmented lesion and edema volumes for identifying RN. RESULTS: Karnofsky performance scale score at presentation significantly predicted pathologic diagnosis on univariate analysis (P = 0.044). Radiation dosage and time from radiation therapy to lesion onset did not differ among pathologic diagnosis groups. No differences existed between RN and TR on quantitative imaging analyses. Multivariate logistic regression found higher Karnofsky performance scale score to be an independent factor associated with TR relative to RN (odds ratio 1.26, 95% confidence interval 1.02-1.56, P = 0.030). CONCLUSIONS: Diagnostic imaging can often be inaccurate in detecting RN alone, even with quantitative volume assessment. Functional status on repeat presentation may increase the likelihood of accurate diagnosis before definitive biopsy when neuroimaging remains unclear.

Quantification of perivascular spaces at 7T: A potential MRI biomarker for epilepsy.

PURPOSE: 7T (7T) magnetic resonance imaging (MRI) facilitates the visualization of the brain with resolution and contrast beyond what is available at conventional clinical field strengths, enabling improved detection and quantification of small structural features such as perivascular spaces (PVSs). The distribution of PVSs, detected in vivo at 7T, may act as a biomarker for the effects of epilepsy. In this work, we systematically quantify the PVSs in the brains of epilepsy patients and compare them to healthy controls. METHODS: T2-weighted turbo spin echo images were obtained at 7T on 21 epilepsy patients and 17 healthy controls. For all subjects, PVSs were manually marked on Osirix image analysis software. Marked PVSs with diameter≥0.5mm were then mapped by hemisphere and lobe. The asymmetry index (AI) was calculated for each region and the maximum asymmetry index (|AImax|) was reported for each subject. The asymmetry in epilepsy subjects was compared to that of controls, and the region with highest asymmetry was compared to the suspected seizure onset zone. RESULTS: There was a significant difference between the |AImax| in epilepsy subjects and in controls (p=0.016). In 72% of patients, the region or lobe of the brain showing maximum PVS asymmetry was the same as the region containing the suspected seizure onset zone. CONCLUSION: These findings suggest that epilepsy may be associated with significantly asymmetric distribution of PVSs in the brain. Furthermore, the region of maximal asymmetry of the PVSs may help provide localization or confirmation of the seizure onset zone.

First Application of 7-T Magnetic Resonance Imaging in Endoscopic Endonasal Surgery of Skull Base Tumors.

BACKGROUND: Successful endoscopic endonasal surgery for the resection of skull base tumors is reliant on preoperative imaging to delineate pathology from the surrounding anatomy. The increased signal-to-noise ratio afforded by 7-T MRI can be used to increase spatial and contrast resolution, which may lend itself to improved imaging of the skull base. In this study, we apply a 7-T imaging protocol to patients with skull base tumors and compare the images with clinical standard of care. METHODS: Images were acquired at 7 T on 11 patients with skull base lesions. Two neuroradiologists evaluated clinical 1.5-, 3-, and 7-T scans for detection of intracavernous cranial nerves and internal carotid artery (ICA) branches. Detection rates were compared. Images were used for surgical planning and uploaded to a neuronavigation platform and used to guide surgery. RESULTS: Image analysis yielded improved detection rates of cranial nerves and ICA branches at 7 T. The 7-T images were successfully incorporated into preoperative planning and intraoperative neuronavigation. CONCLUSIONS: Our study represents the first application of 7-T MRI to the full neurosurgical workflow for endoscopic endonasal surgery. We detected higher rates of cranial nerves and ICA branches at 7-T MRI compared with 3- and 1.5-T MRI, and found that integration of 7 T into surgical planning and guidance was feasible. These results suggest a potential for 7-T MRI to reduce surgical complications. Future studies comparing standardized 7-, 3-, and 1.5-T MRI protocols in a larger number of patients are warranted to determine the relative benefit of 7-T MRI for endonasal endoscopic surgical efficacy.

Imaging of Spinal Manifestations of Hematological Disorders.

Imaging manifestations of hematological diseases and their potential complications are broad, and there may be significant overlap in features of various disease processes. Knowledge of appropriate choice of imaging test, pertinent imaging patterns, and pathophysiology of disease can help the reader increase specificity in the diagnosis and treatment of the patient. Most importantly, we encourage readers of this review to engage their radiologists during the diagnostic, treatment, and management phases of care delivery.

Clinical outcome of vertebral compression fracture after single fraction spine radiosurgery for spinal metastases.

Vertebral compression fracture (VCF) occurs after stereotactic body radiation therapy (SBRT) for spine metastasis. Recently, single fraction radiosurgery (sfSRS) is used more frequently. The aim of this study is to determine the clinical outcome of VCF after sfSRS. Spinal instability neoplastic score (SINS) criteria were used to retrospectively score 143 consecutive vertebral segments in 79 patients treated with SRS. Follow-up MRI, pain, and neurologic assessments obtained every 3-6 months. Pain also scored at 7, 14, and 30 days after sfSRS. Follow up was 16 ± 18 months ±SD, range 3-78. Long-term radiographic control occurred in 94 % of cases. Pain improvement resulted within 7 days in 100 % of cases with severe pain and sustained long-term in 95 %. VCF occurred in 21 % of segments: 30 % were de novo VCF. The overall 1 year fracture free probability (1yFFP) was 76 %. Pre-existing VCF resulted in higher probability to progress: 1yFFP 90 versus 60 %. Symptoms presented in 6 % of cases with de novo VCF and 39 % with progressive. The former were treated with vertebral augmentation (VA), the latter with open surgery. Surgery/VA prior to SRS did not change risk of progressive VCF. Univariate but not multivariate analysis identified histology (colorectal), pre-existing VCF, and pain (severe) as significant predictors of VCF. In conclusion, sfSRS compares favourably to SBRT for radiographic and pain control with similar VCF risk. Patients with pre-existing VCF have a higher probability to progress, become symptomatic, and require surgery. These results may help discussing risk and benefits with patients undergoing sfSRS for spinal metastasis and developing new treatment algorithms.

Recurrent temporal bone tenosynovial giant cell tumor with chondroid metaplasia: the use of imaging to assess recurrence.

Tenosynovial giant cell tumor (TGCT) is a benign proliferative lesion of unclear etiology. It is predominantly monoarticular and involves the synovium of the joint, tendon sheath, and bursa. TGCT of the temporomandibular joint (TMJ) is rare and aggressive resulting in destruction of surrounding structures. The diagnosis may be suggested by imaging, mainly by the MR features and PET/CT, and confirmed by histopathology. We describe the case of a 50-year-old man who presented with right-sided hearing loss, tinnitus and TMJ pain. Pathology revealed tenosynovial giant cell tumor with chondroid metaplasia. Six years later he developed a recurrence, which was documented to our knowledge for the first time with CT, MR and FDG PET/CT imaging.

Comparison of radiation exposure and cost between dynamic computed tomography and sestamibi scintigraphy for preoperative localization of parathyroid lesions.

IMPORTANCE: Dynamic computed tomography (CT) is emerging as a first-line alternative to sestamibi scintigraphy for preoperative localization of parathyroid lesions. In recent years, there has been increased concern over the impact of radiation exposure from medical imaging, as well as on the cost of diagnostic medical procedures. An ideal diagnostic procedure would be cost effective while minimizing hazardous exposures and complication rates. OBJECTIVE: To compare the radiation dose and financial cost of dynamic CT with sestamibi scintigraphy. DESIGN, SETTING, AND PATIENTS: A retrospective review of 263 patients at a large, urban, tertiary referral center who underwent either dynamic parathyroid CT or sestamibi scintigraphy for any etiology of hyperparathyroidism from 2006 through 2010. MAIN OUTCOMES AND MEASURES: The 2 primary study outcomes were radiation exposure measured in millisieverts (mSv) and medical charges for the respective diagnostic procedures. The study was conducted with the hypothesis that dynamic parathyroid CT would have slightly greater radiation exposure with similar cost to sestamibi scintigraphy. RESULTS: Dynamic parathyroid CT and sestamibi scintigraphy delivered mean radiation doses of 5.56 and 3.33 mSv, respectively (P < .05). Charges totaled $1296 for thin-cut dynamic parathyroid CT and a mean of $1112 for sestamibi scintigraphy, depending on the type and amount of radiotracer injected. Although multiphase CT scanning took less than 5 minutes, sestamibi scintigraphy lasted a mean time of 306 minutes. A total of 62 of 119 patients (52%) in the CT group have undergone operative treatment to date, whereas all patients in the sestamibi arm underwent operative treatment of their hyperparathyroidism. Of the patients who underwent a surgical procedure, CT correctly identified the side of the parathyroid adenoma in 54 of 62 patients (87%), while sestamibi scintigraphy only correctly lateralized 90 of 122 adenomas (74%) as confirmed by exploratory surgery, intraoperative parathyroid hormone levels, and pathologic features. A dynamic parathyroid CT correctly predicted multiglandular disease in 1 of 7 patients (14%), while sestamibi scintigraphy correctly predicted multiglandular disease in 8 of 23 patients (35%). CONCLUSIONS AND RELEVANCE: In patients who underwent directed parathyroid surgery, dynamic CT is comparable to sestamibi scintigraphy in patients with hyperparathyroidism. Although CT delivers a higher dose of radiation, the average background radiation exposure in the United States is 3 mSv/y, and added exposures of less than 15 mSv are considered low risk for carcinogenesis. Overall, dynamic parathyroid CT is a safe, cost-effective alternative to sestamibi scintigraphy.