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Andrés Monserrate, Benjamin Zussman, Alp Ozpinar, Ajay Niranjan, John C. Flickinger and Peter C. Gerszten

OBJECTIVE

Cone-beam CT (CBCT) image guidance technology has been widely adopted for spine radiosurgery delivery. There is relatively little experience with spine radiosurgery for intradural tumors using CBCT image guidance. This study prospectively evaluated a series of intradural spine tumors treated with radiosurgery. Patient setup accuracy for spine radiosurgery delivery using CBCT image guidance for intradural spine tumors was determined.

METHODS

Eighty-two patients with intradural tumors were treated and prospectively evaluated. The positioning deviations of the spine radiosurgery treatments in patients were recorded. Radiosurgery was delivered using a linear accelerator with a beam modulator and CBCT image guidance combined with a robotic couch that allows positioning correction in 3 translational and 3 rotational directions. To measure patient movement, 3 quality assurance CBCTs were performed and recorded in 30 patients: before, halfway, and after the radiosurgery treatment. The positioning data and fused images of planning CT and CBCT from the treatments were analyzed to determine intrafraction patient movements. From each of 3 CBCTs, 3 translational and 3 rotational coordinates were obtained.

RESULTS

The radiosurgery procedure was successfully completed for all patients. Lesion locations included cervical (22), thoracic (17), lumbar (38), and sacral (5). Tumor histologies included schwannoma (27), neurofibromas (18), meningioma (16), hemangioblastoma (8), and ependymoma (5). The mean prescription dose was 17 Gy (range 12–27 Gy) delivered in 1–3 fractions. At the halfway point of the radiation, the translational variations and standard deviations were 0.4 ± 0.5, 0.5 ± 0.8, and 0.4 ± 0.5 mm in the lateral (x), longitudinal (y), and anteroposterior (z) directions, respectively. Similarly, the variations immediately after treatment were 0.5 ± 0.4, 0.5 ± 0.6, and 0.6 ± 0.5 mm along x, y, and z directions, respectively. The mean rotational angles were 0.3° ± 0.4°, 0.3° ± 0.4°, and 0.3° ± 0.4° along yaw, roll, and pitch, respectively, at the halfway point and 0.5° ± 0.5°, 0.4° ± 0.5°, and 0.2° ± 0.3° immediately after treatment.

CONCLUSIONS

Radiosurgery offers an alternative treatment option for intradural spine tumors in patients who may not be optimal candidates for open surgery. CBCT image guidance for patient setup for spine radiosurgery is accurate and successful in patients with intradural tumors.

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Jennifer L. Perez, Michael M. McDowell, Benjamin Zussman, Ashutosh P. Jadhav, Yosuke Miyashita, Patrick McKiernan and Stephanie Greene

Aneurysmal rupture can result in devastating neurological consequences and can be complicated by comorbid disease processes. Patients with autosomal recessive polycystic kidney disease (ARPKD) have a low rate of reported aneurysms, but this may be due to the relative high rate of end-stage illnesses early in childhood. Authors here report the case of a 10-year-old boy with ARPKD who presented with a Hunt and Hess grade V subarachnoid hemorrhage requiring emergency ventriculostomy, embolization, and decompressive craniectomy. Despite initial improvements in his neurological status, the patient succumbed to hepatic failure. Given the catastrophic outcomes of subarachnoid hemorrhage in young patients, early radiographic screening in those with ARPKD may be warranted.

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Jennifer L. Perez, Michael M. McDowell, Benjamin Zussman, Ashutosh P. Jadhav, Yosuke Miyashita, Patrick McKiernan and Stephanie Greene

Aneurysmal rupture can result in devastating neurological consequences and can be complicated by comorbid disease processes. Patients with autosomal recessive polycystic kidney disease (ARPKD) have a low rate of reported aneurysms, but this may be due to the relative high rate of end-stage illnesses early in childhood. Authors here report the case of a 10-year-old boy with ARPKD who presented with a Hunt and Hess grade V subarachnoid hemorrhage requiring emergency ventriculostomy, embolization, and decompressive craniectomy. Despite initial improvements in his neurological status, the patient succumbed to hepatic failure. Given the catastrophic outcomes of subarachnoid hemorrhage in young patients, early radiographic screening in those with ARPKD may be warranted.

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Benjamin Zussman, Pascal Jabbour, Kiran Talekar, Richard Gorniak and Adam E. Flanders

Object

Although dynamic, first-pass cerebral CT perfusion is used in the evaluation of acute ischemic stroke, a lack of standardization restricts the value of this imaging modality in clinical decision-making. The purpose of this study was to comprehensively review the reported sources of variability and error in cerebral CT perfusion results.

Methods

A systematic literature review was conducted, 120 articles were reviewed, and 23 published original research articles were included. Sources of variability and error were thematically categorized and presented within the context of the 3 stages of a typical CT perfusion study: data acquisition, postprocessing, and results interpretation.

Results

Seven factors that caused variability were identified and described in detail: 1) contrast media, the iodinated compound injected intravascularly to permit imaging of the cerebral vessels; 2) data acquisition rate, the number of images obtained by CT scan per unit time; 3) user inputs, the subjective selections that operators make; 4) observer variation, the failure of operators to repeatedly measure a perfusion parameter with precision; 5) software operational mode, manual, semiautomatic, or automatic; 6) software design, the mathematical algorithms used to perform postprocessing; and 7) value type, absolute versus relative values.

Conclusions

Standardization at all 3 stages of the CT perfusion study cycle is warranted. At present, caution should be exercised when interpreting CT perfusion results as these values may vary considerably depending on a variety of factors. Future research is needed to define the role of CT perfusion in clinical decision-making for acute stroke patients and to determine the clinically acceptable limits of variability in CT perfusion results.