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Neuromuscular electrical stimulation (NMES) induces involuntary muscle contraction, preferentially promotes anaerobic metabolism, and is applicable for increasing exercise intensity. This study aimed to assess whether superimposing NMES onto moderate-intensity voluntary exercise imitates physiological adaptations that occur in response to vigorous voluntary exercise.Eight participants trained with a cycling ergometer at 100% of the ventilatory threshold (VT) (73.3% of peak oxygen consumption) (VOL), and another nine participants trained with the cycling ergometer at 75% of VT (56.2% of peak oxygen consumption) with subtetanic NMES applied to the gluteus and thigh muscles (VOLES), matched to VOL training sessions, for nine weeks.Rating of perceived exertion (RPE) in VOLES (12.00 ± 1.50) was significantly lower than in VOL (14.88 ± 1.81) (p 0.05) during training sessions. Peak power output during the exercise tolerance test was increased in VOL and VOLES following interventions. Oxygen consumption and heart rate (HR) at VT and blood lactate concentration (BLC) at VT were decreased from before (PRE) to after (POST) training interventions for both VOL and VOLES. There were no significant differences in absolute changes from PRE to POST for peak power output and oxygen consumption, HR, and BLC at a submaximal intensity between VOL and VOLES.Our results suggest that both superimposing subtetanic NMES onto moderate-intensity voluntary exercise and vigorous voluntary intensity exercise induce the improvement in cardiovascular and metabolic systems, but the adaptation of former method is provided without perceived strenuous exertion.

Triplet repeat diseases (TRDs) refer to a group of diseases caused by three nucleotide repeats elongated beyond a pathologic threshold. TRDs are divided into the following four groups depending on the pathomechanisms, although the pathomechanisms of several diseases remain unelucidated: polyglutamine disorders, caused by a pathologic repeat expansion of CAG (coding the amino acid glutamine) located within the exon; loss-of-function repeat disorders, characterized by the common feature of a loss of function of the gene within which they occur; RNA gain-of-function disorders, involving the production of a toxic RNA species; and polyalanine disorders, caused by a pathologic repeat expansion of GCN (coding the amino acid alanine) located within the exon. Many of these TRDs manifest through neurologic symptoms; moreover, neuroimaging, especially brain magnetic resonance imaging, plays a pivotal role in the detection of abnormalities, differentiation, and management of TRDs. In this article, we reviewed the clinical and neuroimaging features of TRDs. An early diagnosis of TRDs through clinical and imaging approaches is important and may contribute to appropriate medical intervention for patients and their families.

Hypophysitis is an inflammatory disease affecting the pituitary gland. Hypophysitis can be classified into multiple types depending on the mechanisms (primary or secondary), histology (lymphocytic, granulomatous, xanthomatous, plasmacytic/IgG4 related, necrotizing, or mixed), and anatomy (adenohypophysitis, infundibulo-neurohypophysitis, or panhypophysitis). An appropriate diagnosis is vital for managing these potentially life-threatening conditions. However, physiological morphological alterations, remnants, and neoplastic and non-neoplastic lesions may masquerade as hypophysitis, both clinically and radiologically. Neuroimaging, as well as imaging findings of other sites of the body, plays a pivotal role in diagnosis. In this article, we will review the types of hypophysitis and summarize clinical and imaging features of both hypophysitis and its mimickers.

Background Modular organization in muscular control is generally specified as synergistic muscle groups that are hierarchically organized. There are conflicting perspectives regarding modular organization for regulation of walking speeds, with regard to whether modular organization is relatively consistent across walking speeds. This conflict might arise from different stride time (time for one stride) and stride length combinations for achieving the same walking speed. Research question Does the regulation of the modular organization depend on stride time and stride length (stride time-length) combinations? Methods Ten healthy men walked at a moderate speed (nondimensional speed = 0.4) on a treadmill at five different stride time-length combinations (very short, short, preferred, long, and very long). Surface electromyograms from 16 muscles in the trunk and lower limb were recorded. The modular organization was modeled as muscle synergies, which represent groups of synchronously activated muscles. Muscle synergies were extracted using a decomposition technique. The number of synergies and their activation durations were analyzed. Results The number of synergies was consistent in the preferred and quasi-preferred condition (median: 4.5 [short], 4.5 [preferred], 5 [long]), while it varied in the extreme condition (median: 4 [very short] and 6 [very long]; 0.02 ≤ p ≤ 0.09). Gait parameters (stride time, stride length, stance time, swing time, and double stance time) were significantly different for preferred and quasi-preferred conditions (p Significance Our results provide additional insights on the flexibility of modular control during walking, namely that the number of synergies or activations are fine-tuned even within one walking speed. Our finding implies that a variety of walking patterns can be achieved by consistent synergies except for extreme walking patterns.

Although there are many types of inborn errors of metabolism (IEMs) affecting the central nervous system, also referred to as neurometabolic disorders, individual cases are rare, and their diagnosis is often challenging. However, early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurological impairment or death. The clinical course of IEMs is very diverse, with some diseases progressing to acute encephalopathy following infection or fasting while others lead to subacute or slowly progressive encephalopathy. The diagnosis of IEMs relies on biochemical and genetic tests, but neuroimaging studies also provide important clues to the correct diagnosis and enable the conditions to be distinguished from other, more common causes of encephalopathy, such as hypoxia–ischemia. Proton magnetic resonance spectroscopy (1H-MRS) is a powerful, non-invasive method of assessing neurological abnormalities at the microscopic level and can measure in vivo brain metabolites. The present review discusses neuroimaging findings, including those of 1H-MRS, of IEMs focusing on intoxication disorders such as urea cycle disorders, aminoacidopathies, and organic acidopathies, which can result in acute life-threatening metabolic decompensation or crisis.

Angiocentric gliomas (AGs) are epileptogenic low-grade gliomas in young patients. We aimed to investigate the MRI findings of AGs and systematically review previous publications and three new cases.We searched PubMed, Elsevier's abstract and citation database, and Embase databases and included 50 patients with pathologically proven AGs with analyzable preoperative MRI including 3 patients from our institution and 47 patients from 38 publications (median age, 13 years [range, 2-83 years]; 35 men). Two board-certified radiologists reviewed all images. The relationships between seizure/epilepsy history and MRI findings were statistically analyzed. Moreover, clinical and imaging differences were evaluated between supratentorial and brainstem AGs.Intratumoral T1-weighted high-intensity areas, stalk-like signs, and regional brain parenchymal atrophy were observed in 23 out of 50 (46.0%), 10 out of 50 (20.0%), and 14 out of 50 (28.0%) patients, respectively. Intratumoral T1-weighted high-intensity areas were observed significantly more frequently in patients with stalk-like signs (positive, 9/10 vs. negative, 14/40, p = .0031) and regional atrophy (13/14 vs. 10/36, p = .0001). There were significant relationships between the length of seizure/epilepsy history and presence of intratumoral T1-weighted high-intensity area (median 3 years vs. 0.5 years, p = .0021), stalk-like sign (13.5 vs. 1 year, p .0001), and regional atrophy (14 vs. 0.5 years, p .0001). Patients with brainstem AGs (n = 7) did not have a seizure/epilepsy history and were significantly younger than those with supratentorial AGs (median, 5 vs. 13 years, p .0001, respectively).Intratumoral T1-weighted high-intensity areas, stalk-like signs, and regional brain atrophy were frequent imaging features in AG. We also found that affected age was different between supratentorial and brainstem AGs.

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by multiple immunologic abnormalities and has the potential to involve the central nervous system (CNS). The prevalence of SLE seems to be growing, possibly because of earlier diagnosis and improved survival; however, the associated mortality is still high. The mortality is associated with disease-related risk factors such as lupus disease activity, young age, and organ damage or with antiphospholipid syndrome (APS). Neuropsychiatric SLE (NPSLE), which is caused by SLE-related CNS involvement, comprises a broad range of neurologic and psychiatric manifestations with varying severity, which can make this disease indistinguishable from other conditions that are unrelated to SLE. No unifying pathophysiology has been found in the etiology of NPSLE, suggesting that this condition has multiple contributors such as various immune effectors and the brain-intrinsic neuroimmune interfaces that are breached by the immune effectors. The postulated neuroimmune interfaces include the blood-brain barrier, blood-cerebrospinal fluid barrier, meningeal barrier, and glymphatic system. On the basis of the immunologic, pathologic, and imaging features of NPSLE, the underlying pathophysiology can be classified as vasculitis and vasculopathy, APS, demyelinating syndrome, or autoimmune antibody-mediated encephalitis. Each pathophysiology has different imaging characteristics, although the imaging and pathophysiologic features may overlap. Moreover, there are complications due to the immunocompromised status caused by SLE per se or by SLE treatment. Radiologists and clinicians should become familiar with the underlying mechanisms, radiologic findings, and complications of NPSLE, as this information may aid in the diagnosis and treatment of NPSLE.

Plexopathy may be caused by diverse pathologies, including trauma, nerve entrapment, neoplasm, inflammation, infection, autoimmune disease, hereditary disease, and idiopathic etiologies. For patients presenting with brachial or lumbosacral plexopathy, dedicated plexus MRI is the most appropriate initial imaging modality for all clinical scenarios and can identify processes both intrinsic and extrinsic to the nerves. Other imaging tests may be appropriate for initial imaging depending on the clinical scenario. This document addresses initial imaging strategies for brachial and lumbosacral plexopathy in the following clinical situations: nontraumatic plexopathy with no known malignancy, traumatic plexopathy (not perinatal), and plexopathy occurring in the context of a known malignancy or posttreatment syndrome. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Spine infection is both a clinical and diagnostic imaging challenge due to its relatively indolent and nonspecific clinical presentation. The diagnosis of spine infection is based upon a combination of clinical suspicion, imaging evaluation and, when possible, microbiologic confirmation performed from blood cultures or image-guided percutaneous or open spine biopsy. With respect to the imaging evaluation of suspected spine infection, MRI without and with contrast of the affected spine segment is the initial diagnostic test of choice. As noncontrast MRI of the spine is often used in the evaluation of back or neck pain not responding to conservative medical management, it may show findings that are suggestive of infection, hence this procedure may also be considered in the evaluation of suspected spine infection. Nuclear medicine studies, including skeletal scintigraphy, gallium scan, and FDG-PET/CT, may be helpful in equivocal or select cases. Similarly, radiography and CT may be appropriate for assessing overall spinal stability, spine alignment, osseous integrity and, when present, the status of spine instrumentation or spine implants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

In the United States, acute low back pain, with or without radiculopathy, is the leading cause of years lived with disability and the third ranking cause of disability-adjusted life-years. Uncomplicated acute low back pain and/or radiculopathy is a benign, self-limited condition that does not warrant any imaging studies. Imaging is considered in those patients who have had up to 6 weeks of medical management and physical therapy that resulted in little or no improvement in their back pain. It is also considered for those patients presenting with red flags, raising suspicion for a serious underlying condition, such as cauda equina syndrome, malignancy, fracture, or infection. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

PurposeTo demonstrate Dynamic Contrast-Enhanced (DCE) perfusion changes in brain metastasis patients after chemoradiation therapy within the treatment responders (true-response group and pseudoprogression group) and between the true-response and pseudoprogression groups.Materials and Methods38 true-response patients with 38 brain metastases (13 melanoma, 11 lung, 7 breast, 7 others) with 3 consecutive DCE-MRI examinations (pretreatment, first follow-up and second follow-up) and 7 pseudoprogression patients with 10 melanoma metastases with 2 consecutive DCE-MRI examinations (pretreatment, first follow-up) were evaluated. DCE-MRI parameters and permeability graphs increase (rapid, slow, medium) and course pattern (washout, plateau, persistent) were analyzed and compared between the timing of the examinations and between the true-response and pseudoprogression groups, using paired t-tests and Mann-Whitney U-tests as appropriate. Automatic assessment of washout curves by Olea Brain Software was reviewed.ResultsPretreatment mean wash-in (15.3±24.7 vs 6.50±14.2, P4±18×104vs 5×104±10×104, PConclusionWash-in, Vp, Ktrans, peak enhancement, AUC values in DCE perfusion were significantly decreased after chemoradiation therapy in the responders. No statistically significant difference was shown between the true-response and pseudoprogression groups on either pre-or post-treatment, indicating the homogeneous permeability profiles in the responders.

This study aimed to evaluate the diagnostic performance of dynamic susceptibility contrast (DSC) perfusion magnetic resonance imaging and apparent diffusion coefficient (ADC) for differentiating common posterior fossa tumors, pilocytic astrocytoma (PA), medulloblastoma (MB), and hemangioblastoma (HB). Between January 2016 and April 2022, we enrolled 23 (median age, 7 years [range, 2-26]; 12 female), 13 (10 years [1-24]; 3 female), and 12 (43 years [23-73]; 7 female) patients with PA, MB, and HB, respectively. Normalized relative cerebral blood volume and flow (nrCBV and nrCBF) and normalized mean ADC (nADCmean) were calculated from volume-of-interest and statistically compared. nADCmean was significantly higher in PA than in MB (PA: median, 2.2 [range, 1.59-2.65] vs MB: 0.93 [0.70-1.37], P .001). nrCBF was significantly higher in HB than in PA and MB (PA: 1.10 [0.54-2.26] vs MB: 1.62 [0.93-3.16] vs HB: 7.83 [2.75-20.1], all P .001). nrCBV was significantly different between all 3 tumor types (PA: 0.89 [0.34-2.28] vs MB: 1.69 [0.93-4.23] vs HB: 8.48 [4.59-16.3], P = .008 for PA vs MB; P .001 for PA vs HB and MB vs HB). All tumors were successfully differentiated using an algorithmic approach with a threshold value of 4.58 for nrCBV and subsequent threshold value of 1.38 for nADCmean. DSC parameters and nADCmean were significantly different between PA, MB, and HB. An algorithmic approach combining nrCBV and nADCmean may be useful for differentiating these tumor types.

Invasive fungal rhinosinusitis (IFRS) is a serious infection that is associated with high morbidity and mortality rates. The incidence of IFRS has been increasing, mainly because of the increased use of antibiotics and immunosuppressive drugs. Rhino-orbital cerebral mucormycosis has recently reemerged among patients affected by COVID-19 and has become a global concern. The detection of extrasinus involvement in its early stage contributes to improved outcomes; therefore, imaging studies are essential in establishing the degree of involvement and managing the treatment properly, especially in immunocompromised patients. The common sites of extrasinus fungal invasion are the intraorbital, cavernous sinus, and intracranial regions. Fungi spread directly to these regions along the blood vessels or nerves, causing devastating complications such as optic nerve ischemia or compression, optic neuritis or perineuritis, orbital cellulitis, cavernous sinus thrombosis, mycotic aneurysm, vasculitis, internal carotid arterial occlusion, cerebral infarction, cerebritis, and brain abscess. IFRS has a broad imaging spectrum, and familiarity with intra- and extrasinonasal imaging features, such as loss of contrast enhancement of the affected region, which indicates tissue ischemia due to angioinvasion of fungi, and the surrounding anatomy is essential for prompt diagnosis and management. The authors summarize the epidemiology, etiology, risk factors, and complications of IFRS and review the anatomy and key diagnostic imaging features of IFRS beyond the sinonasal regions.

This retrospective study aimed to investigate the radiological features of head and neck mammary analogue secretory carcinoma (MASC) and systematically review previous publications and 11 new cases. We included patients with pathologically proven MASCs with preoperative CT or MRI images, including 11 patients from our hospital and 29 patients from 28 publications extracted after screening 645 abstracts. Two board-certified radiologists reviewed and evaluated all radiological images. The frequency of metastasis during the follow-up period in tumors with well- and ill-defined margins was compared using a Fisher’s exact test. The median age at diagnosis was 52.5 years (range, 7–78 years; 20 males). Of the 40 patients, those in their 50 s were the most common (10/40, 25.0%), and the main tumor site was the parotid gland (27/40, 42.5%). Characteristic radiological features included high intensity on T1WI in the cystic components and tumors frequently showed “papillary and cystic,” which showed a projection into the cystic components, or “non-papillary and cystic” morphology, which did not show projection of the solid components. Tumor metastasis was found in 10/35 patients (28.6%) during the follow-up period, with a significant difference in frequency between the tumors with well- and ill-defined margin (well-defined (4/26) vs. ill-defined (6/9); P = 0.0074). MASCs are newly recognized malignant tumors. Characteristic T1WI high intensity on MRI and predominant cystic morphology may reflect its unique histological profile. Ill-defined tumor margin status was related to frequent metastasis. Awareness of these characteristic radiological features can assist radiologists in better detection of this novel entity.

We aimed to evaluate the differences in dynamic susceptibility contrast (DSC)- magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) parameters between the pre- and postbiopsy MRI obtained before treatment in patients with diffuse midline glioma, H3K27-altered. The data of 25 patients with pathologically proven diffuse midline glioma, H3K27-altered, were extracted from our hospital's database between January 2017 and August 2021. Twenty (median age, 13 years; range, 3-52 years; 12 women) and 8 (13.5 years; 5-68 years; 1 woman) patients underwent preoperative DSC-MRI and DWI before and after biopsy, respectively. The normalized corrected relative cerebral blood volume (ncrCBV), normalized relative cerebral blood flow (nrCBF), and normalized maximum, mean, and minimum apparent diffusion coefficient (ADC) were calculated using the volumes-of-interest of the tumor and normal-appearing reference region. The macroscopic postbiopsy changes (i.e., biopsy tract, tissue defect, and hemorrhage) were meticulously excluded from the postbiopsy measurements. The DSC-MRI and DWI parameters of the pre- and postbiopsy groups were compared using the Mann-Whitney U test. The ncrCBV was significantly lower in the postbiopsy group than in the prebiopsy group [prebiopsy group: median 1.293 (range, 0.513 to 2.547) versus postbiopsy group: 0.877 (0.748 to 1.205), P = .016]. No significant difference was observed in the nrCBF and normalized ADC values, although the median nrCBF was lower in the postbiopsy group. The DSC-MRI parameters differed between the pre- and postbiopsy MRI obtained pretreatment, although the macroscopic postbiopsy changes were carefully excluded from the analysis. The results emphasize the potential danger of integrating and analyzing DSC-MRI parameters derived from pre- and postbiopsy MRI.

Skull metastasis (SM) is a common secondary malignancy. We evaluated the diagnostic performance of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (MRI) in differentiating SM from osseous venous malformations and SM of various origins.This study included 31 patients with SM (median age, 64 years; range, 41-87 years; 29 women; 24 and 7 patients with breast and non-small cell lung cancer, respectively) and 16 with osseous venous malformations (median age, 68 years; range, 20-81 years; 10 women) who underwent both DWI and dynamic contrast-enhanced MRI between January 2015 and October 2021. Normalized mean apparent diffusion coefficients (ADCs) and dynamic contrast-enhanced MRI parameters were compared between SM and osseous venous malformations, and between breast cancer and non-small cell lung cancer. Multivariate stepwise logistic regression analyses were performed to identify statistically significant parameters.Plasma volume and time-to-maximum enhancement were the most statistically significant parameters for differentiating SM from osseous venous malformations, with an area under the receiver operating characteristic curve of 0.962. The normalized mean ADC and peak enhancement values were the most statistically significant parameters for differentiating breast cancer from non-small cell lung cancer, with an area under the curve of 0.924.Our results highlight the efficacious diagnostic performance of DWI and dynamic contrast-enhanced MRI in distinguishing SM from osseous venous malformations and differentiating SM of various origins.

The World Health Organization (WHO) published the fifth edition of the

Background and purpose The prediction of radiotherapy outcome in head and neck paragangliomas is clinically important. We investigated perfusion and diffusion markers for evaluation of response to radiotherapy of head and neck paragangliomas. Methods We retrospectively reviewed 330 consecutive patients from January 2016 to September 2019 with suspected head and neck paragangliomas, and enrolled 11 patients (2 males, 9 females; age: 55.2 ± 10.3 years) who had conventional MRI and dynamic contrast-enhanced (DCE)-MRI before and after radiation therapy. Radiation therapy, consisting of external beam radiotherapy or stereotactic radiotherapy, was conducted at the radiation oncology department in a single center. Mean apparent diffusion coefficient (ADC), normalized mean ADC, and parameters of DCE-MRI were compared between pre- and post-treatment status by paired t-test. The Pearson correlation coefficient was used for the relationship between tumor volume ratio (post-treatment status/pre-treatment status) and pre-treatment and post-treatment values. Results Mean and normalized ADC values were statistically higher in post-treatment status than pre-treatment status (p = 0.005, p = 0.005, respectively), and Ktrans (volume transfer constant between extravascular, extracellular space [EES], and blood plasma per minute) and Kep (rate transfer constant between EES and blood plasma per minute) were significantly lower in post-treatment status than pre-treatment status (p = 0.007, p = 0.027, respectively). The correlation coefficient of the relationship between tumor volume ratio and pre-treatment Ktrans (r = 0.70; p = 0.016) and between tumor volume ratio and post-treatment Ktrans and Kep (r = 0.83; p = 0.002, r = 0.8; p = 0.003, respectively) was statistically significant. Conclusions Ktrans has predictive potential to predict the response to radiation therapy of head and neck paragangliomas.

BACKGROUND AND PURPOSE: Head and neck paragangliomas have been reported to be associated with mutations of the succinate dehydrogenase enzyme family. The aim of this study was to assess whether radiologic features could differentiate between paragangliomas in the head and neck positive and negative for the succinate dehydrogenase mutation. MATERIALS AND METHODS: This single-center retrospective review from January 2015 to January 2020 included 40 patients with 48 paragangliomas (30 tumors positive for succinate dehydrogenase mutation in 23 patients and 18 tumors negative for the succinate dehydrogenase mutation in 17 patients). ADC values and tumor characteristics on CT and MR imaging were evaluated by 2 radiologists. Differences between the 2 cohorts in the diagnostic performance of ADC and normalized ADC (ratio to ADC in the medulla oblongata) values were evaluated using the independent samples t test. P < .05 was considered significant. RESULTS: ADC(mean) (1.07 [SD, 0.25]/1.04 [SD, 0.12] versus 1.31 [SD, 0.16]/1.30 [SD, 0.20]× 10(−3) mm(2)/s by radiologists 1 and 2; P

Myelopathy is a clinical diagnosis with localization of the neurological findings to the spinal cord, rather than the brain or the peripheral nervous system, and then to a particular segment of the spinal cord. Myelopathy can be the result of primary intrinsic disorders of the spinal cord or from secondary conditions, which result in extrinsic compression of the spinal cord. While the causes of myelopathy may be multiple, the acuity of presentation and symptom onset frame a practical approach to the differential diagnosis. Imaging plays a crucial role in the evaluation of myelopathy with MRI the preferred modality. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Human biarticular muscles are regionally activated for different functional roles, and this should be considered when recording surface electromyography., Biarticular muscles have traditionally been considered to exhibit homogeneous neuromuscular activation. The regional activation of biarticular muscles, as revealed from high-density surface electromyograms, seems however to discredit this notion. We thus hypothesize the regional activation of biarticular muscles may contribute to different actions about the joints they span. We then discuss the mechanistic basis and methodological implications underpinning our hypothesis.

Paragangliomas are neuroendocrine tumors that derive from paraganglia of the autonomic nervous system, with the majority of parasympathetic paragangliomas arising in the head and neck. More than one-third of all paragangliomas are hereditary, reflecting the strong genetic predisposition of these tumors. The molecular basis of paragangliomas has been investigated extensively in the past couple of decades, leading to the discovery of several molecular clusters and more than 20 well-characterized driver genes (somatic and hereditary), which are more than are known for any other endocrine tumor. Head and neck paragangliomas are largely related to the pseudohypoxia cluster and have been previously excluded from most molecular profiling studies. This review article introduces the molecular classification of paragangliomas, with a focus on head and neck paragangliomas, and discusses its impact on the management of these tumors. Genetic testing is now recommended for all patients with paragangliomas to provide screening and surveillance recommendations for patients and relatives. While CT and MRI provide excellent anatomic characterization of paragangliomas, gallium 68 tetraazacyclododecane tetraacetic acid–octreotate (ie, (68)Ga-DOTATATE) has superior sensitivity and is recommended as first-line imaging in patients with head and neck paragangliomas with concern for multifocal and metastatic disease, patients with known multifocal and metastatic disease, and in candidates for targeted peptide-receptor therapy. Keywords: Molecular Imaging, MR Perfusion, MR Spectroscopy, Neuro-Oncology, PET/CT, SPECT/CT, Head/Neck, Genetic Defects © RSNA, 2022

The authors present an atypical case of presumed stroke-like migraine attacks after radiation therapy (SMART) syndrome in the brainstem. A 29-year-old male, who had been treated with resection and subsequent craniospinal radiation for posterior fossa medulloblastoma 21 years before, presented with subacute progressive left hemiparesis evolving over 4 days. Hematological findings, cerebrospinal fluid (CSF), and electroencephalogram (EEG) were unremarkable. Magnetic resonance imaging (MRI) showed a round area of hyperintense FLAIR signal centered within the pons associated with central restricted diffusion, peripheral enhancement, and small paramagnetic low susceptibility signal foci consistent with petechial hemorrhage. Positron emission tomography (PET), perfusion MRI, and MR spectroscopy revealed no evidence of tumor recurrence. The diagnosis of SMART syndrome is presumed from the conventional and advanced imaging findings, clinical history, and clinical course.