4/17/2024 0 Comments Mri safe dorsal column stimulator10 Except for a single study in the early 2000s comparing brain and chest MRI safety, 19 to our knowledge, no studies have investigated the safety profile of body MRI, particularly spine MRI, in DBS patients. 10 With most of these indications (62%) calling for body and/or spine MRI, there is evident value in establishing a safe MRI protocol for these patients. 24, 27 Underscoring the clinical demand for MRI in this unique patient population, one study estimated that 66%–75% of patients diagnosed with PD, essential tremor, or dystonia need to undergo MRI within 10 years of DBS surgery. CT of the spine is insufficient for visualizing nonbony structures, while CT myelography is generally inferior to MRI and can be associated with complications such as bleeding, infection, seizures, and contrast-induced nephrotoxicity. With the exception of acute intracranial indications, MRI is the diagnostic imaging modality of choice for most cranial and spinal clinical queries. In addition, reducing the number of slices typically warrants radiologist supervision to ensure that adequate anatomy is imaged. SAR or B1+rms requirements can be met by reducing the number of slices/echoes or increasing the repetition time, which usually lengthens the acquisition time. 6, 13 However, these guidelines prohibit the use of most routine clinical MRI protocols, unless they are modified. 5, 23 These MRI restrictions are in place mainly to prevent heating of the DBS system (particularly the electrode tips) and potential brain injury. The SAR should remain ≤ 0.1 W/kg during the MRI session. These thresholds are based on a specific absorption rate (SAR) and root-mean-square (rms) value of the MRI effective component of the radiofrequency (RF) magnetic (B 1) field (B1+rms). For MRI safety purposes, the spine is considered within the category of “full body.” DBS devices are approved for MRI at specific magnetic field strengths (i.e., 1.5 T) and with specific heating-related thresholds. 5, 23, 32 Depending on the models of the DBS leads, extension wires, and IPG, patients may be eligible for head or full-body MRI. 15 At present, FDA-approved MRI conditional DBS devices are available from Medtronic, Boston Scientific, and Abbott. 15, 31, 35 In particular, one case of peri-electrode hemorrhage and permanent neurological changes occurred during a 1.0-T lumbar spine (L-spine) MRI session. 7, 12, 20, 33 Prior studies have investigated the safety of brain MRI in these patients, 6, 7, 13, 26 but safety data for MRI of other body parts, such as the spine, are lacking.ĭue to 3 previous cases of DBS patient injuries presumed to be related to MRI, MRI guidelines for DBS systems have become restrictive, as well as vendor and hardware specific. Because of safety concerns and stringent vendor guidelines, MRI of patients following DBS implantation is highly restricted. The IPG is typically placed subcutaneously in the upper chest wall. DBS electrodes are connected to an implantable pulse generator (IPG) via extension wires that are tunneled under the skin. 21 DBS surgery entails the insertion of electrodes into deep brain structures and modulation of desired brain targets using electric current. In recent years, it has also become of interest as a treatment strategy for psychiatric and cognitive disorders, such as major depressive disorder, obsessive-compulsive disorder, and, possibly, Alzheimer’s disease. 14 DBS is best established as a therapy for movement disorders, including Parkinson’s disease (PD), essential tremor, and dystonia. T o date, more than 150,000 patients have received deep brain stimulation (DBS) neuromodulation devices worldwide.
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