Contrast Media in Pregnant and Lactating Patients, From the AJR Special Series on Contrast Media.

IV contrast media improve the diagnostic power of radiology examinations. These media include gadolinium-based contrast media and iron-oxide nanoparticles for MRI, iodinated contrast material for CT, microbubbles for ultrasound, and radiopharmaceuticals for nuclear medicine. As for all medications, contrast media carry risks, which may be heightened in the conditions of pregnancy and lactation. Radiologists must understand the potential risks from contrast media exposure to the pregnant patient, fetus, and nursing infant, as well as understand these administrations' impact on examinations' clinical utility. This article reviews the available literature on these media, along with key regulatory bodies' and professional societies' current recommendations for their use, in the settings of pregnancy and lactation. This knowledge should help radiologists make well-reasoned risk-benefit analyses regarding contrast media administration and provide informed consent discussions with pregnant and nursing patients in whom contrast media administration is being considered. This information and analysis can also assist facilities in designing policies and standard operating procedures of possible clinical benefit to the pregnant patient, fetus, or nursing infant, balancing contrast media exposure considerations versus augmented diagnostic capabilities.

Prospective evaluation of the utility of magnetic resonance imaging in patients with non-MRI-conditional pacemakers and defibrillators.

BACKGROUND: Magnetic resonance imaging (MRI) in patients with legacy cardiovascular implantable electronic devices (CIEDs) in situ is likely underutilized. We hypothesized the clinical benefit of MRI would outweigh the risks in legacy CIED patients. METHODS: This is a single-center retrospective study that evaluated and classified the utility of MRI using a prospectively maintained database. The outcomes were classified as aiding in diagnosis, treatment, or both for the patients attributable to the MRI. We then assessed the incidence of adverse effects (AE) when the MRI was performed. RESULTS: In 668, MRIs performed on 479 patients, only 13 (1.9%) MRIs did not aid in the diagnosis or treatment of the patient. Power-on reset events without clinical sequelae in three scans (0.45%) were the only AE. The probability of an adverse event happening without any benefit from the MRI scan was 1.1 × 10-4 . A maximum benefit in diagnosis using MRI was obtained in ruling out space-occupying lesions (121/185 scans, 65.4%). Scans performed in patients for elucidating answers to queries in treatment were most frequently done for disease staging at long term follow-up (167/470 scans, 35.5%). Conservative treatment (184/470 scans, 39%) followed by medication changes (153/470 scans, 28.7%) were the most common treatment decisions made. CONCLUSIONS: The utility of MRI in patients with non-MRI-conditional CIEDs far outweighs the risk of adverse events when imaging is done in the context of a multidisciplinary program that oversees patient safety.

ACR guidance document on MR safe practices: Updates and critical information 2019.

The need for a guidance document on MR safe practices arose from a growing awareness of the MR environment's potential risks and adverse event reports involving patients, equipment, and personnel. Initially published in 2002, the American College of Radiology White Paper on MR Safety established de facto industry standards for safe and responsible practices in clinical and research MR environments. The most recent version addresses new sources of risk of adverse events, increases awareness of dynamic MR environments, and recommends that those responsible for MR medical director safety undergo annual MR safety training. With regular updates to these guidelines, the latest MR safety concerns can be accounted for to ensure a safer MR environment where dangers are minimized. Level of Evidence: 1 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:331-338.

Safety Considerations of 7-T MRI in Clinical Practice.

Although 7-T MRI has recently received approval for use in clinical patient care, there are distinct safety issues associated with this relatively high magnetic field. Forces on metallic implants and radiofrequency power deposition and heating are safety considerations at 7 T. Patient bioeffects such as vertigo, dizziness, false feelings of motion, nausea, nystagmus, magnetophosphenes, and electrogustatory effects are more common and potentially more pronounced at 7 T than at lower field strengths. Herein the authors review safety issues associated with 7-T MRI. The rationale for safety concerns at this field strength are discussed as well as potential approaches to mitigate risk to patients and health care professionals.

Augmenting MRI Safety Screening Processes: Reliable Identification of Cardiac Implantable Electronic Devices by a Ferromagnetic Detector System.

LEVEL OF EVIDENCE: 1 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;49:e297-e299.

Patient-oriented education and visual-aid intervention are inadequate to identify patients with potential capsule retention: a prospective randomized study.

Background/aims: The key procedure-related risk with video capsule endoscopy (VCE) is capsule retention, which should be suspected in patients who have not reported capsule passage. The study aims were to determine the frequency of capsule passage visualization and the difference in self-reporting of capsule passage between patients who receive patient-oriented education (POE) and patients who receive POE and a visual aid intervention in the form of a wrist band (WB). Methods: This was a prospective randomized study that enrolled patients undergoing VCE. Patients were randomly assigned to a POE group versus a POE and WB group. POE consisted of verbal education and an information booklet. Both groups received instructions to notify the study team regarding capsule passage. Results: Sixty patients (mean age 57 ± 18 years; 61% female) were included. A total of 57 patients were included in the analysis (3 lost to follow-up; 28 in POE group; 29 in WB group). Capsule passage status was reported by 68% without significant difference between POE and WB groups (72% vs. 64%; p = .51). Capsule passage status was obtained from all 57 patients with the addition of a proactive follow-up. Only 56% (n = 32) reported visualizing capsule passage. Of the remaining patients who did not visualize capsule passage, 60% (n = 15) reported on this without significant difference between the POE and WB groups (p = .23). Conclusions: Lack of visualization of capsule passage is a poor indicator of retention. Self-reporting of VCE passage status is suboptimal and the addition of a visual aid did not improve this parameter.

Expanded phenotypes and outcomes among 256 LGI1/CASPR2-IgG-positive patients.

OBJECTIVE: To describe an expanded phenotypic spectrum and longitudinal outcome in 256 LGI1-IgG-seropositive and/or CASPR2-IgG-seropositive patients. METHODS: Patients were identified through service neural autoantibody evaluation. Ninety-five had longitudinal follow-up (7-456 months; median = 35). RESULTS: Among 3,910 patients tested, 196 were LGI1-IgG positive, 51 were CASPR2-IgG positive, and 9 were dual positive. Cerebrospinal fluid testing was less sensitive than serum testing, detecting only 24 of 38 (63%) LGI1-IgG-positive and 5 of 6 (83%) CASPR2-IgG-positive patients. LGI1-IgG-positive specimens had higher voltage-gated potassium channel-IgG immunoprecipitation values (0.33nmol/l, range = 0.02-5.14) than CASPR2-IgG-positive specimens (0.10nmol/l, range = 0.00-0.45, p < 0.001). Of patients presenting with pain or peripheral nervous system (PNS) manifestations, 39% were LGI1-IgG seropositive (7% had solely neuropathy or pain). Multivariate analysis identified age as the only significant predictor of central nervous system (CNS) versus PNS involvement (>50 years; odds ratio = 15, p < 0.001). Paroxysmal dizziness spells (PDS), a unique LGI1-IgG accompaniment (14% of patients), frequently delayed the diagnosis. T2-mesiotemporal hyperintensity was more common in LGI1-IgG-positive (41%) than in CASPR2-IgG-positive patients (p = 0.033). T1-bright basal ganglia were confined to LGI1-IgG-positive patients with faciobrachial-dystonic seizures (9 of 39, 31%). Cancer was found in 44% of LGI1-IgG/CASPR2-IgG dual seropositive patients (one-third thymoma). Response to initial immunotherapy was favorable in 97%; mean modified Rankin score was 3 (range = 1-5) at onset and 1.74 (range = 0-6) at last follow-up, with 9% having severe refractory disability, 20% being asymptomatic, 28% receiving immunotherapy, and 58% receiving antiepileptic medication. INTERPRETATION: Older age is a strong predictor of CNS involvement in patients seropositive for CASPR2-IgG or LGI1-IgG. Pain, peripheral manifestations, and stereotypic paroxysmal dizziness spells are common with LGI1-IgG. Response to initial immunotherapy is often favorable, but some patients remain severely disabled, requiring long-term immunotherapy and/or antiepileptic medications. Ann Neurol 2017;82:79-92.

MR Imaging and Cochlear Implants with Retained Internal Magnets: Reducing Artifacts near Highly Inhomogeneous Magnetic Fields.

The number of patients receiving cochlear implants and auditory brainstem implants for severe to profound sensorineural hearing loss has rapidly increased. These implants consist of an internal component implanted between the skull and the temporal scalp and an external removable speech processor unit. A small magnet within the internal component is commonly used to hold the external speech processor unit in place. Several cochlear implant models have recently received U.S. Food and Drug Administration and European Economic Area regulatory approval to allow magnetic resonance (MR) imaging examinations to be performed under certain specified conditions. The small internal magnet presents a challenge for imaging of the head and neck near the implant, creating a nonlinear magnetic field inhomogeneity and significant MR imaging artifacts. Fat-saturation failures and susceptibility artifacts severely degrade image quality. Typical artifacts at diffusion-weighted imaging and accelerated imaging are exacerbated. Each examination may require impromptu adjustments to allow visualization of the tissue or contrast of interest. Patients may also be quite uncomfortable during the examination, as a result of either imposed magnetic forces or a tight head wrap that is often applied to minimize internal magnet movement. Translational forces and torque sometimes displace the implanted magnet even when a head wrap is used. Diseases such as neurofibromatosis type 2 that are associated with bilateral vestibular schwannomas and hearing loss often require lifelong tumor surveillance with MR imaging. A collaborative team of radiologists, technologists, and/or medical physicists or MR imaging scientists, armed with strategies to mitigate artifacts near implanted magnets, can customize the examination for better visualization of tissue and consistent comparison examinations over time. ©RSNA, 2018.

Magnetic Resonance Imaging in Nondependent Pacemaker Patients with Pacemakers and Defibrillators with a Nearly Depleted Battery.

BACKGROUND: Magnetic resonance imaging (MRI) in patients with non-MRI-conditional cardiac implantable electronic devices (CIEDs) has been shown to be safe when performed under closely monitored protocols. However, the safety of MRI in patients with devices with a nearly depleted battery has not been reported. METHODS: Prospective data were collected between January 2008 and May 2015 in patients with non-MRI-conditional CIEDs undergoing clinically indicated MRI under institutional protocol. Patients who were pacemaker dependent were excluded. Patients whose devices were at elective replacement indicator (ERI) at the time of MRI or close to ERI (ERI or replacement for battery depletion within 3 months of scan) were identified through database review and analyzed for clinical events. RESULTS: MRI scans (n = 569) were performed in 442 patients. Of these, we identified 13 scans performed with a nearly depleted battery in nine patients. All scans with implantable cardioverter defibrillators (ICDs, n = 9) were uneventful. However, two scans with pacemakers close to ERI resulted in a power-on-reset (PoR) event. One scan with a pacemaker close to ERI that was programmed to DOO mode reached ERI during MRI and automatically changed to VVI mode. Additionally, one scan with a pacemaker at ERI did not allow programming. All pacemakers with events were implanted before 2005. CONCLUSION: Patients with pacemakers and ICDs with a nearly depleted battery can safely undergo MRI when patients are not pacemaker dependent. Attention should be paid because old devices can result in PoR or ERI during MRI, which may lead to oversensing and inhibition of pacing.

Paraspinal neurofibromas and hypertrophic neuropathy in Noonan syndrome with multiple lentigines.

BACKGROUND: Noonan syndrome with multiple lentigines (NSML), formerly known as LEOPARD syndrome, is an autosomal-dominant disorder characterised by lentigines, EKG abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, growth retardation and deafness. There is significant clinical overlap between NSML and other disorders that result from dysregulated rat sarcoma/mitogen-activated protein kinase pathway (RASopathies). Except for neurofibromatosis type 1, other RASopathies are not known to be typically associated with neurogenic tumours. METHODS AND RESULTS: We evaluated patients from three families with pigmentary skin lesions, progressive neuropathy, enlarged nerves, massive burden of paraspinal tumours (neurofibroma was confirmed in one patient) and a clinical diagnosis of NSML. All patients had a mutation in the protein tyrosine phosphatase catalytic domain of the PTPN11 gene; two unrelated patients had the p.Thr468Met mutation, while the family consisting of two affected individuals harboured the p.Thr279Cys mutation. Molecular analysis performed on hypertrophic nerve tissue did not disclose a second somatic hit in NF1, PTPN11, NF2 or SMARCB1 genes. CONCLUSIONS: Neurogenic tumours and hypertrophic neuropathy are unusual complications of NSML and may be an under-recognised manifestation that would warrant surveillance. Our observation may also have implications for other disorders caused by RAS-pathway dysregulation.

Magnetic resonance imaging-guided laser interstitial thermal therapy for previously treated hypothalamic hamartomas.

OBJECTIVE Hypothalamic hamartomas (HHs) are associated with gelastic seizures and the development of medically refractory epilepsy. Magnetic resonance imaging-guided laser interstitial thermal therapy (MRg-LITT) is a minimally invasive ablative treatment that may have applicability for these deep-seated lesions. Here, the authors describe 3 patients with refractory HHs who they treated with MRg-LITT. METHODS An institutional review board-approved prospective database of patients undergoing Visualase MRg-LITT was retrospectively reviewed. Demographic and historical medical data, including seizure and medication histories, previous surgeries, procedural details, and surgical complications, along with radiological interpretation of the HHs, were recorded. The primary outcome was seizure freedom, and secondary outcomes included medication reduction, seizure frequency, operative morbidity, and clinical outcome at the latest follow-up. RESULTS All 3 patients in the multi-institutional database had developed gelastic seizures related to HH at the ages of 7, 7, and 9 years. They presented for further treatment at 25, 28, and 48 years of age, after previous treatments with stereotactic radiosurgery in all cases and partial hamartoma resection in one case. One ablation was complicated by a small tract hemorrhage, which was stable on postoperative imaging. One patient developed hyponatremia and experienced weight gain, which were respectively managed with fluid restriction and counseling. At the most recent follow-up at a mean of 21 months (range 1-32 months), one patient was seizure free while another had meaningful seizure reduction. Medication was reduced in one case. CONCLUSIONS Adults with gelastic seizures despite previous treatments can undergo MRg-LITT with reasonable safety and efficacy. This novel therapy may provide a minimally invasive alternative for primary and recurrent HH as the technique is refined.

Presentation and Medical Management of Fibrocartilaginous Embolism in the Emergency Department.

BACKGROUND: Fibrocartilaginous embolism is an exceedingly rare condition that was formerly a clinical diagnosis based on mechanism of injury, physical examination findings, and older magnetic resonance imaging (MRI) technologies without a specific histologic diagnosis. Spinal cord MRI diffusion-weighted imaging allows for a more specific diagnosis. CASE REPORT: A 14-year-old male felt a sudden pop in his back while running sprints in his gym class. He slowly developed bilateral lower extremity weakness and urinary incontinence, prompting an emergency department evaluation. A MRI scan of his lumbar spine revealed degeneration, desiccation, and bulging of the T12-L1 disc with an accompanying subacute Schmorl's nodule. There was adjacent cord swelling and central cord T2 hyperintensity, with accompanying restricted diffusion consistent with spinal cord infarction. These findings, in conjunction with paraplegia and mechanism of injury, were highly suggestive of fibrocartilaginous embolism. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: An emergent MRI scan with the proper sequencing and immediate consultation with a spine surgery specialist are important to exclude a compressive myelopathy that would necessitate acute surgical decompression. There is significant uncertainty in the initial management and stabilization of this rare condition that has not been addressed in the emergency medicine literature.

Focal encephalitis following varicella-zoster virus reactivation without rash in a healthy immunized young adult.

Herein we describe an episode of focal varicella-zoster virus (VZV) encephalitis in a healthy young man with neither rash nor radicular pain. The symptoms began with headaches and seizures, after which magnetic resonance imaging detected a single hyperintense lesion in the left temporal lobe. Because of the provisional diagnosis of a brain tumor, the lesion was excised and submitted for pathological examination. No tumor was found. But the tissue immunostained positively for VZV antigens, and wild-type VZV sequences were detected. In short, this case represents VZV reactivation, most likely in the trigeminal ganglion, in the absence of clinical herpes zoster.

Safety and outcomes of magnetic resonance imaging in patients with abandoned pacemaker and defibrillator leads.

INTRODUCTION: Abandoned cardiovascular implantable electronic device (CIED) leads remain a contraindication to magnetic resonance imaging (MRI) studies, largely due to in vitro data showing endocardial heating secondary to the radiofrequency field. We tested the hypothesis that abandoned CIED leads do not pose an increased risk of clinical harm for patients undergoing MRI. METHODS: This single-center retrospective study examined the outcomes of patients who had device generators removed before MRI, rendering the device leads abandoned. Information was gathered through chart review. Data collected included lead model, pacing threshold before MRI, anatomic region examined, threshold data after generator reimplantation, and clinical patient outcome. RESULTS: Patients (n = 19, 11 men and eight women) ranged in age from 19 to 85 at the time of MRI. There was a mean of 1.63 abandoned leads at the time of imaging; none of the leads were MRI conditional. Of the three implantable cardioverter defibrillator (ICD) leads, two of three were dual coil. Most (31/35) of the scans performed were of the central nervous system, including head and spinal imaging. There were no adverse events associated with MRI in any of these patients with abandoned leads within 7 days of the scan. No lead malfunctions or clinically significant change in pacing thresholds were noted with generator reimplantation. CONCLUSION: The use of MRI in patients with abandoned cardiac device leads appears feasible when performed under careful monitoring, with no adverse events, although the experience is small. MRI did not affect the function of leads that were subsequently reconnected to a cardiac device.

Safety Considerations in MRI and CT.

OBJECTIVE: MRI and CT are indispensable imaging modalities for the evaluation of patients with neurologic disease, and each is particularly well suited to address specific clinical questions. Although both of these imaging modalities have excellent safety profiles in clinical use as a result of concerted and dedicated efforts, each has potential physical and procedural risks that the practitioner should be aware of, which are described in this article. LATEST DEVELOPMENTS: Recent advancements have been made in understanding and reducing safety risks with MR and CT. The magnetic fields in MRI create risks for dangerous projectile accidents, radiofrequency burns, and deleterious interactions with implanted devices, and serious patient injuries and deaths have occurred. Ionizing radiation in CT may be associated with shorter-term deterministic effects on biological tissues at extremely high doses and longer-term stochastic effects related to mutagenesis and carcinogenesis at low doses. The cancer risk of radiation exposure in diagnostic CT is considered extremely low, and the benefit of an appropriately indicated CT examination far outweighs the potential risk. Continuing major efforts are centered on improving image quality and the diagnostic power of CT while concurrently keeping radiation doses as low as reasonably achievable. ESSENTIAL POINTS: An understanding of these MRI and CT safety issues that are central to contemporary radiology practice is essential for the safe and effective treatment of patients with neurologic disease.

Magnetic Resonance Imaging in Patients with Cochlear Implants without Magnet Removal: A Radiology-Administered Protocol to Enhance Operational Efficiency and Improve Workflow.

OBJECTIVE: To describe the development, implementation, and validation of a radiology-administered protocol to obtain magnetic resonance imaging (MRI) in patients with cochlear implants and auditory brainstem implants without magnet removal. STUDY DESIGN: Retrospective review and description of novel care pathway. METHODS: A radiology-administered protocol was designed based on careful input from the radiology safety committee and neurotology. Radiology technologist training modules, consent instructions, patient educational material, clinical audits, and other safeguards were implemented, with samples provided in this report. The primary outcomes measured included instances of magnet displacement during MRI and premature termination of MRI studies secondary to pain. RESULTS: Between June 19, 2018, and October 12, 2021, 301 implanted ears underwent MRI without magnet removal, including 153 devices housing diametric MRI-conditional magnets, and 148 implants with conventional axial (i.e., nondiametric) magnets. Among cases with diametric MRI-conditional magnets, all studies were completed without magnet dislodgement or need to terminate imaging early due to pain. Among cases with conventional axial (nondiametric) magnets, 29 (19.6%) MRI studies were stopped prematurely secondary to pain or discomfort; the overall rate of this event was 9.6% (29 of 301) among the entire study cohort. In addition, 6.1% (9 of 148) experienced confirmed magnet displacement despite headwrap placement; the overall rate among all cases was 3.0% (9 of 301). Eight of these patients received successful external magnet reseating through manual pressure on the external scalp without surgery, and one required surgical replacement of the magnet in the operating room. There were no documented instances of hematoma, infection, device or magnet extrusion, internal device movement (i.e., gross receiver-stimulator migration), or device malfunction in this cohort related to MRI. CONCLUSIONS: We present the successful implementation of a radiology-administered protocol designed to streamline care for cochlear implant and auditory brainstem implant recipients who require MRI and ease clinical demands for otolaryngology providers. Examples of resources developed, including a process map, radiology training modules, consent instructions, patient educational materials, clinical audit, and other procedural safety measures are provided so interested groups may consider adapting and implementing related measures according to need.

Safety of magnetic resonance imaging in patients with surgically implanted permanent epicardial leads.

BACKGROUND: Magnetic resonance imaging (MRI) safety in patients with an epicardial cardiac implantable electronic device (CIED) is uncertain. OBJECTIVE: The purpose of this study was to assess the safety and adverse effects of MRI in patients who had surgically implanted epicardial CIED. METHODS: Patients with surgically implanted CIEDs who underwent MRI with an appropriate cardiology-radiology collaborative protocol between January 2008 and January 2021 were prospectively studied in 2 clinical centers. All patients underwent close cardiac monitoring through MRI procedures. Outcomes were compared between the epicardial CIED group and the matched non-MRI-conditional transvenous CIED group. RESULTS: Twenty-nine consecutive patients with epicardial CIED (41.4% male; mean age 43 years) underwent 52 MRIs in 57 anatomic regions. Sixteen patients had a pacemaker, 9 had a cardiac defibrillator or cardiac resynchronization therapy-defibrillator, and 4 had no device generator. No significant adverse events occurred in the epicardial or transvenous CIED groups. Battery life, pacing, sensing thresholds, lead impedance, and cardiac biomarkers were not significantly changed, except 1 patient had a transient decrease in atrial lead sensing function. CONCLUSION: MRI of CIEDs with epicardially implanted leads does not represent a greater risk than transvenous CIEDs when performed with a multidisciplinary collaborative protocol centered on patient safety.

Evaluation of a compact 3 T MRI scanner for patients with implanted devices.

Access to high-quality MR exams is severely limited for patients with some implanted devices due to labeled MR safety conditions, but small-bore systems can overcome this limitation. For example, a compact 3 T MR scanner (C3T) with high-performance gradients can acquire exams of the head, extremities, and infants. Because of its reduced bore size and the patient being advanced only partially into the bore, the associated electromagnetic (EM) fields drop off rapidly caudal to the head, compared to whole-body systems. Therefore, some patients with MR conditional implanted devices can safely receive 3 T brain exams on the C3T using its strong gradients and a multiple-channel receive coil, while a corresponding exam on whole-body MR is precluded. The purpose of this study is to evaluate the performance of a small-bore scanner for subjects with MR conditional spinal or sacral nerve stimulators, or abandoned cardiac implantable electronic device (CIED) leads. The spatial dependence of specific absorption rate (SAR) on the C3T was compared to whole-body scanners. A device assessment tool was developed and applied to evaluate MR safety individually on the C3T for 12 subjects with implanted devices or abandoned CIED leads. Once MR safety was established, the subjects received a C3T brain exam along with their clinical, 1.5 T exam. The resulting images were graded by three board-certified neuroradiologists. The C3T exams were well-tolerated with no adverse events, and significantly outperformed the whole-body 1.5 T exams in terms of overall image quality.

Altered functional MR imaging language activation in elderly individuals with cerebral leukoaraiosis.

PURPOSE: To test the hypothesis that leukoaraiosis alters functional activation during a semantic decision language task. MATERIALS AND METHODS: With institutional review board approval and written informed consent, 18 right-handed, cognitively healthy elderly participants with an aggregate leukoaraiosis lesion volume of more than 25 cm(3) and 18 age-matched control participants with less than 5 cm(3) of leukoaraiosis underwent functional MR imaging to allow comparison of activation during semantic decisions with that during visual perceptual decisions. Brain statistical maps were derived from the general linear model. Spatially normalized group t maps were created from individual contrast images. A cluster extent threshold of 215 voxels was used to correct for multiple comparisons. Intergroup random effects analysis was performed. Language laterality indexes were calculated for each participant. RESULTS: In control participants, semantic decisions activated the bilateral visual cortex, left posteroinferior temporal lobe, left posterior cingulate gyrus, left frontal lobe expressive language regions, and left basal ganglia. Visual perceptual decisions activated the right parietal and posterior temporal lobes. Participants with leukoaraiosis showed reduced activation in all regions associated with semantic decisions; however, activation associated with visual perceptual decisions increased in extent. Intergroup analysis showed significant activation decreases in the left anterior occipital lobe (P=.016), right posterior temporal lobe (P=.048), and right basal ganglia (P=.009) in particpants with leukoariosis. Individual participant laterality indexes showed a strong trend (P=.059) toward greater left lateralization in the leukoaraiosis group. CONCLUSION: Moderate leukoaraiosis is associated with atypical functional activation during semantic decision tasks. Consequently, leukoaraiosis is an important confounding variable in functional MR imaging studies of elderly individuals.