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Applications of dual-energy computed tomography and virtual non-contrast technique in neuroimaging are still emerging. While the role of DECT in differentiating parenchymal hemorrhage and contrast media after mechanical revascularization is well recognized, the value of DECT in evaluation of brain ischemia in post resuscitation patients who have received intravenous (IV) iodinated contrast is not well documented. We present a challenging case where DECT helped explain hyperattenuation in cortical grey matter and deep grey nuclei as well as cerebellar hemispheres in a comatose patient post cardiac arrest following massive pulmonary embolism.

Since its approval in treating a number of movement disorders, magnetic resonance imaging–guided focused ultrasound (MRgFUS) has been adopted rapidly as one of the standard treatment modalities internationally. However, the efficiency of the energy delivered by the ultrasonic waves is largely determined by the highly variable bone morphology and density characteristics of the skull. One of the widely accepted indices used to facilitate patient selection is the skull density ratio (SDR). Earlier literature suggested that an SDR of less than 0.4 would be unfavorable for MRgFUS treatment. Some prior studies have excluded patients with hyperostosis. However, there is little published data regarding the impact of other skull features such as hyperostosis on treatment success. We present the case of a 66-year-old man with medically refractory essential tremor who had an SDR of 0.38 and extensive hyperostosis frontalis interna and underwent attempted MRgFUS thalamotomy treatment. However, intraoperatively the treatment was unsuccessful in generating sufficiently elevated temperature to create a lesion of the usual desired volume, and as expected, there was minimal clinical improvement. For comparison, we also summarize a case series of 4 other patients with an SDR of less than 0.4 who had successful outcomes. We believe that SDR should not be used as the only means of selecting patients for MRgFUS. Instead, important factors such as hyperostosis should be taken into consideration for patient selection and pretreatment counseling.

Spinal metastases are most commonly osseous and may extend to the epidural space. Less commonly, spinal metastases can be subdural, leptomeningeal, or intramedullary. Among these, subdural metastases are the most rare, with few reported cases. While these lesions are now almost exclusively detected on MRI, they can rarely be apparent on other modalities. It is important to recognize subdural metastases on any modality, because they have a significant impact on patient prognosis and treatment. We report a case of renal cell carcinoma in a 68-year-old male initially presenting with subdural metastases detected on CT myelography, with subsequent confirmation by MRI. The case illustrates, to our knowledge, the first example of subdural metastatic disease seen on CT myelography.

Objective: To provide an initial report that patients with magnetic resonance imaging (MRI) non-conditional cardiac implanted electronic device (CIED) can undergo state-of-the-art magnetic resonance imaging–guided focused (MRgFUS) ablation procedures with careful planning and integration of the procedure into an established CIED MRI practice. Patient and Methods: We describe an MRgFUS ablation treatment of lumbar facet joints in a patient with an MRI non-conditional CIED (pacemaker), completed in accordance with our institutional CIED/MRI practice guidelines. Results: A risk-benefit analysis by a coordinated multidisciplinary team before this treatment was performed to account for the risks associated with the MRI non-conditional pacemaker in the context of the MRgFUS procedure. Conclusion: The patient had no adverse cardiac event during or following this procedure.

Magnetic resonance imaging–guided focused ultrasound (MRgFUS) is a noninvasive modality that allows for precise tissue ablation with sparing of surrounding structures. Early reports of the use of MRgFUS for the treatment of facet joint osteoarthritis are promising. We present a case of facet joint pain treated successfully by MRgFUS at our institution. Magnetic resonance imaging–guided focused ultrasonography may be a useful modality for patients with facet joint–mediated low back pain, particularly in the setting of limited or refractory response to conventional treatments.