Use of Magnetic Resonance Neurography for Evaluating the Distribution and Patterns of Chronic Inflammatory Demyelinating Polyneuropathy

OBJECTIVE: To evaluate the distribution and characteristics of peripheral nerve abnormalities in chronic inflammatory demyelinating polyneuropathy (CIDP) using magnetic resonance neurography (MRN) and to examine the diagnostic efficiency.MATERIALS AND METHODS: Thirty-one CIDP patients and 21 controls underwent MR scans. Three-dimensional sampling perfections with application-optimized contrasts using different flip-angle evolutions and T1-/T2- weighted turbo spin-echo sequences were performed for neurography of the brachial and lumbosacral (LS) plexus and cauda equina, respectively. Clinical data and scores of the inflammatory Rasch-built overall disability scale (I-RODS) in CIDP were obtained.RESULTS: The bilateral extracranial vagus (n = 11), trigeminal (n = 12), and intercostal nerves (n = 10) were hypertrophic. Plexus hypertrophies were observed in the brachial plexus of 19 patients (61.3%) and in the LS plexus of 25 patients (80.6%). Patterns of hypertrophy included uniform hypertrophy (17 [54.8%] brachial plexuses and 21 [67.7%] LS plexuses), and multifocal fusiform hypertrophy (2 [6.5%] brachial plexuses and 4 [12.9%] LS plexuses) was present. Enlarged and/or contrast-enhanced cauda equina was found in 3 (9.7%) and 13 (41.9%) patients, respectively. Diameters of the brachial and LS nerve roots were significantly larger in CIDP than in controls (p < 0.001). The largest AUC was obtained for the L5 nerve. There were no significant differences in the course duration, I-RODS score, or diameter between patients with and without hypertrophy.CONCLUSION: MRN is useful for the assessment of distribution and characteristics of the peripheral nerves in CIDP. Compared to other regions, LS plexus neurography is more sensitive for CIDP.

Accessory Belly of the Piriformis Muscle as a Cause of Piriformis Syndrome: a Case Report with Magnetic Resonance Imaging and Magnetic Resonance Neurography Imaging Findings

Piriformis syndrome caused by an accessory belly of the piriformis muscle is very rare. Only a few cases have been reported. Here, we report a case of piriformis syndrome resulting from an extremely rare type of accessory belly of the piriformis muscle originated at the proximal third portion of the main piriformis muscle and attached separately to the greater trochanter inferior to the insertion of the main piriformis muscle. A definitive diagnosis of piriformis syndrome was made based on magnetic resonance imaging and magnetic resonance neurography findings that were consistent with results of nerve conduction study and needle electromyography.

Neurografía por resonancia magnética para la identificación de la neuralgia del nervio pudendo / Magnetic resonance neurography for the identification of pudendal neuralgia

La neuralgia del nervio pudendo (NP) es una entidad poco estudiada por imágenes. Se reconocen varias causas, tales como compresión a través de su paso por estructuras ligamentarias; estiramiento por partos laboriosos; lesiones secundarias a cirugías rectales, perineales, urológicas y ginecológicas, traumatismos con o sin fractura de huesos pelvianos; procesos inflamatorios/autoinmunes; tumores del NP, y, compresión/desplazamiento por tumores o seudotumores de pelvis. El diagnóstico de neuralgia del NP se sospecha por la clínica y se confirma por diferentes métodos, tales como las pruebas electrofisiolológicas: potenciales evocados, test de latencia motora terminal y electromiograma, y, a través de bloqueos neurales y resonancia magnética. La neurografía por resonancia magnética de alta resolución, debería ser empleada como estudio diagnóstico complementario junto a la clínica y exámenes electrofisiológicos, en los pacientes con sospecha de neuralgia del NP.

The pudendal nerve entrapment is an entity understudied by diagnosis imaging. Various causes are recognized in relation to difficult labors, rectal, perineal, urological and gynecological surgery, pelvic trauma fracture, bones tumors and compression by tumors or pelvic pseudotumors. Pudendal neuropathy should be clinically suspected, and confirmed by different methods such as electrofisiological testing: evoked potentials, terminal motor latency test and electromyogram, neuronal block and magnetic resonance imaging. The radiologist should be acquainted with the complex anatomy of the pelvic floor, particularly on the path of pudendal nerve studied by magnetic resonance imaging. High resolution magnetic resonance neurography should be used as a complementary diagnostic study along with clinical and electrophysiological examinations in patients with suspected pudendal nerve neuralgia.

Utilidad de la neurografía por IRM en el diagnóstico de la meralgia parestésica / Usefulness of MRI neurography in the diagnosis of meralgia paresthetica

Objetivo: Evidenciar cómo la Imagen Resonancia magnética (IRM) con equipo de 3 Tesla, utilizando secuencias neurográficas específicas y uso de contraste endovenoso permite ubicar el área de lesión nerviosa. Caso clínico: Mujer de 17 años con hipoestesia y parestesias en la región anterior y lateral del muslo izquierdo, se le realiza un estudio de Resonancia Magnética (RM) en equipo Philips Achieva 3 T, usando protocolo neurográfico y contraste endovenoso, demostrando engrosamiento y cambios de señal del nervio y realce post-contraste característico de la neuropraxia. Conclusión: el caso presentado demuestra el valor actual de los estudios de IRM con técnica neurográfica en la evaluación de la patología de los nervios periféricos. Es fundamental utilizar secuencias adecuadas, realizar un estudio comparativo bilateral y en lo posible usar medios de contraste endovenoso para aumentar la sensibilidad. Estos hallazgos resultan de gran importancia a la hora de planificar la estrategia quirúrgica.

Objective: Demonstrate the usefulness of Magnetic Resonance Imaging (MRI) with equipment 3 Tesla using neurographics specific sequences and use of intravenous contrast can locate the area of nerve injury.Clinical case: 17 year old woman with hypoesthesia and paresthesia in the anterior and lateral region of the left thigh, the study of Magnetic Resonance Imaging (MRI) equipment Philips Achieva 3 T, using neurographic protocol and intravenous contrast, showing thickening and changes signal nerve and post-contrast enhancement characteristic in neuropraxia.Conclusión: the case presented shows the current value of MRI studies with neurographics technique in assessing the pathology of peripheral nerves. It is essential to use appropriate sequences, make a bilateral comparative study and possible use of intravenous contrast media to increase sensitivity. These findings are of great importance when planning the surgical strategy.

The value of Turbo inversion recovery magnitude (TIRM) magnetic resonance neurography for sacral plexus injury / 中华显微外科杂志

Objective To evaluate the capability of Turbo inversion recovery magnitude (TIRM) magnetic resonance neurography (MRN) in the diagnosie of sacral plexus injury by comparing MRN findings with surgical results.Methods Ten patients with sacral plexus injury confirmed surgically underwent conventional T1WI,T2WI,TIRM and coronal TIRM MRN before operations from June,2011 to December,2012.The MRI data and surgical data were analyzed retrospectively to observe nerve injury.Results The coronal TIRM MRN images displayed 93 trunks of sacral plexus,of which 37 were confirmed injury by operation.The MRI findings were as follows:6 trunks involved continuous nerves,but with thickening and blurred margin,as well as abnormal high signal intensity;22 trunks were continuous,but with distortion,stiffness and adhesion accompanied by heterogeneous signal intensity and structural disorder;3 trunks showed complete loss of continuity,absence of normal signal,accompanied by retraction;and 3 trunks involved formation of traumatic neurofibroma.The coincidence of injured nerve trunks diagnosed by MRN with surgical findings amounts to 81.08％ (30/37).Conclusion MR with coronal TIRM imaging is effective in the diagnosis and depiction of sacral plexus injury,therefore it can be used as conventional sequence in sacral plexus examination to detect sacral plexus avulsion.

Detecting Peripheral Nerves in the Elbow using Three-Dimensional Diffusion-Weighted PSIF Sequences: a Feasibility Pilot Study

PURPOSE: To analyze the feasibility of three-dimensional (3D) diffusion-weighted (DW) PSIF (reversed FISP [fast imaging with steady-state free precession]) sequence in order to evaluate peripheral nerves in the elbow. MATERIALS AND METHODS: Ten normal, asymptomatic volunteers were enrolled (6 men, 4 women, mean age 27.9 years). The following sequences of magnetic resonance images (MRI) of the elbow were obtained using a 3.0-T machine: 3D DW PSIF, 3D T2 SPACE (sampling perfection with application optimized contrasts using different flip angle evolution) with SPAIR (spectral adiabatic inversion recovery) and 2D T2 TSE (turbo spin echo) with modified Dixon (m-Dixon) sequence. Two observers used a 5-point grading system to analyze the image quality of the ulnar, median, and radial nerves. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of each nerve were measured. We compared 3D DW PSIF images with other sequences using the Wilcoxon-signed rank test and Friedman test. Inter-observer agreement was measured using intraclass correlation coefficient (ICC) analysis. RESULTS: The mean 5-point scores of radial, median, and ulnar nerves in 3D DW PSIF (3.9/4.2/4.5, respectively) were higher than those in 3D T2 SPACE SPAIR (1.9/2.8/2.8) and 2D T2 TSE m-Dixon (1.7/2.8/2.9) sequences (P < 0.05). The mean SNR in 3D DW PSIF was lower than 3D T2 SPACE SPAIR, but there was no difference between 3D DW PSIF and 2D T2 TSE m-Dixon in all of the three nerves. The mean CNR in 3D DW PSIF was lower than 3D T2 SPACE SPAIR and 2D T2 TSE m-Dixon in the median and ulnar nerves, but no difference among the three sequences in the radial nerve. CONCLUSION: The three-dimensional DW PSIF sequence may be feasible to evaluate the peripheral nerves around the elbow in MR imaging. However, further optimization of the image quality (SNR, CNR) is required.

Neurografía por resonancia magnética en la evaluación de los nervios periféricos / Magnetic resonance neurography in the evaluation of peripheral nerves

Magnetic resonance neurography (MRN), with high resolution sequences, allows for a detailed study of the plexus and peripheral nerves. For its interpretation, it is necessary to have a general knowledge of MR, as well as of the anatomy of the neuromuscular system and lesions that affect it. Nerve and plexus pathology can be divided into mononeuropathies (for trauma, entrapment or tumors) and hereditary polyneuropathies (such as Charcot-Marie-Tooth disease) or acquired (for chronic idiopathic demyelinating polyradiculoneuropathy, diabetes, vasculitis or inflammation). The objective of this review is to describe the study technique of Magnetic Resonance Neurography as well as the characteristics of the normal and pathological peripheral nerve.

La neurografía por resonancia magnética (NRM), con secuencias de alta resolución, permite un detallado estudio de los plexos y nervios periféricos. Para su interpretación, es necesario contar con conocimientos generales de RM, así como de la anatomía del sistema neuromuscular y de las lesiones que lo afectan. La patología de los nervios y plexos puede dividirse en mononeuropatías (por trauma, atrapamiento o tumores) y polineuropatías hereditarias (como la enfermedad de Charcot Marie Tooth) o adquiridas (por poliradiculoneuropatía desmielinizante idiopática crónica, diabetes, vasculitis o inflamación) El objetivo de esta revisión es describir la técnica de estudio de la neurografía por resonancia magnética, así como las características del nervio periférico normal y patológico.

Neuralgic Amyotrophy Manifesting as Mimicking Posterior Interosseous Nerve Palsy

The upper trunk of the brachial plexus is the most common area affected by neuralgic amyotrophy (NA), and paresis of the shoulder girdle muscle is the most prevalent manifestation. Posterior interosseous nerve palsy is a rare presentation in patients with NA. It results in dropped finger on the affected side and may be misdiagnosed as entrapment syndrome or compressive neuropathy. We report an unusual case of NA manifested as PIN palsy and suggest that knowledge of clinical NA phenotypes is crucial for early diagnosis of peripheral nerve palsies.

Magnetic Resonance Neurographic Findings in Classic Idiopathic Neuralgic Amyotrophy in Subacute Stage: A Report of Four Cases

Neuralgic amyotrophy (NA) is characterized by acute onset of severe pain, followed by muscular weakness and wasting of the shoulder girdle. While the diagnosis of NA mainly relies on the clinical history and examination, some investigations including electrophysiologic study and radiologic study may help to confirm the diagnosis. Magnetic resonance neurography (MRN), a new technique for the evaluation of peripheral nerve disorders, can be helpful in the diagnosis of NA. MRN presents additional benefits in comparison to conventional magnetic resonance imaging in the diagnosis of idiopathic NA (INA). In this report, we present the first four cases of classic INA diagnosed with MRN in subacute stage. MRN imaging modality should be considered in patients clinically suspected of INA.

Evaluación de los plexos y nervios periféricos con neurografía por RM de alta resolución en 3T / Evaluation of peripheral plexuses and nerves with high resolution MRI neurography in 3T

La neurografía por RM, se ha convertido en una modalidad diagnóstica ampliamente utilizada para la evaluación de los nervios periféricos y plexos lumbosacro y braquial.El estudio de las NP tradicionalmente perteneció al campo de la neurofisiología, siendo el electromiograma (EMG) el método más utilizado. La neurografía por RM, permite evaluar la estructura fascicular normal de los nervios y los tejidos perineurales, diferenciándolos entre si y, de esa manera detectar y caracterizar anormalidades. En este trabajo, revisamos la anatomía del nervio periférico y del tejido perineural por RM, descripción de las secuencias neurográficas en RM 3T, mención de las patologías que afectan a los nervios periféricos y los plexos braquial y lumbosacro, así como una descripción de las anormalidades musculares que derivan de las lesiones de los nervios periféricos.

Magnetic Resonance Neurography has become a diagnostic tool extensively used for the evaluation of peripheral nerves, lumbosacral and braquial plexus.Traditionally, neuropathies have been assessed by electrophysiological means, being EMG the tool most frequently used.MR Neurography makes it possible to distinguish the normal fascicular pattern of nerves and perineural tissues, and to detect and characterize the abnormalities.In this article we describe the anatomy of peripheral nerves and perineural tissues, the neurography sequences in MRI 3T, the most prevalent diseases that affect them, and the muscle abnormalities that originate from the denervation.

Neurografía por resonancia magnética en 3T: experiencia preliminar / 3T MRI neurography: preliminary experience

Propósito. Presentar las ventajas de la secuencia IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation) en la evaluación de los nervios periféricos y plexos braquial (PB) y lumbosacro (PLS) para el diagnóstico de las neuropatías por atrapamiento o compresión, las neuropatías sin atrapamiento y las condiciones subyacentes. La secuencia IDEAL proporciona 4 tipos de imágenes a partir de una sola adquisición, permitiendo la supresión uniforme de la grasa y el agua, y la obtención de imágenes en fase o fuera de fase de agua, grasa o de la combinación de éstas. Materiales y Métodos. Estudio retrospectivo de enero de 2011 a junio de 2011. Se realizaron 11 neurografías con secuencia IDEAL en resonancia magnética 3T (HDX.3T, GE Healthcare, USA), con bobinas phased array de 8 canales en planos coronal y sagital, cortes de 1,2 - 0 mm, y plano axial 3D spoiled gradient recalled (SPGR) T1, cortes 1 - 0 mm sin y con gadolinio. El campo de visión (FOV) fue variable según el nervio o plexo a explorar. Resultados. Se encontraron 2 schwannomas (plexo braquial, nervio ciático), 1 neuritis (inflamación por compresión del nervio mediano), 2 casos con neurofibromas múltiples (uno en plexo lumbosacro y ciático y otro en plexo braquial), 3 neuromas postraumáticos (ciático poplíteo externo -CPE-), una avulsión con pseudomeningocele (plexo braquial) y 2 casos sin alteraciones (plexo lumbosacro y ciático poplíteo externo). Conclusión. En esta presentación preliminar, la neurografía por resonancia magnética (RM) mostró una excelente diferenciación entre el nervio y las estructuras circundantes y permitió reconocer la estructura del nervio y su señal, determinar variantes anatómicas y causas de neuropatías, así como también se pudieron evaluar los cambios de denervación en los grupos musculares involucrados.

3T MRI neurography: preliminary experience. Purpose. Demonstrate the advantages of the IDEAL(Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation) sequence in the evaluation of peripheral nerves, brachial plexus and lumbar plexus, for the diagnosis of compression or entrapment neuropathies, non-entrapment neuropathies, and the underlying conditions. The IDEAL sequence provides 4 types of images from a single acquisition, allowing uniform fat or water suppression and in phase/out of phase images of water, fat or a combination of both. Materials and Methods. This is a retrospective study, from January 2011 to June 2011. Eleven neurographies were performed on 3T MRI (HDX 3T, GE Healthcare, USA), with 8-channel phased array coils on sagittal and coronal planes, with 1.2-0 mm slices with no gap, axial 3D spoiled gradient recalled (SPGR) T , with 1-0-mm slice thickness with and without gadolinium injection and variable field of view (FOV) according to the nerve or plexus to explore. Results. We found 2 schwannomas (brachial plexus and sciatic nerve), 1 neuritis (compression to median nerve), 2cases of multiple neurofibromas (lumbosacral plexus, sciatic nerve, brachial plexus), 3 traumatic neuromas (peroneal nerve) and 1 pseudomeningocele avulsion (brachial plexus),and 2 with no structural alterations (lumbosacral plexus and peroneal nerve). Conclusion. In this preliminary experience, the use of highresolution sequences in magnetic resonance imaging neurography studies provided excellent signal homogeneity, improving the recognition of the nerve structure and signal,the identification of anatomical variations, and causes of neuropathy, as well as the characterization of denervation changes of the affected muscle groups.

Magnetic resonance neurography of lumbar plexus in healthy people / 重庆医科大学学报

Objective:To Compare the difference between the data of normal lumbar plexus nerve measured through magnetic resonance neurography(MRN) with specimen. Methods:Volunteers of 30 healthy lumbar plexus nerve cases(19 males and 11 females) were selected, to measure the short shaft line and neuromuscular signal ratio of the right normal lumbar nerve root, ganglia, nerve and the femoral nerve stem, anatomy and measurements of the right lumbar plexus L2~5 nerve root,ganglia and nerve stem, femoral nerve morphology and size. And comparison of MRN measurement data and autopsy measurement data were conducted. Results:MRN could clearly show L2~5 nerve course, ganglion being circle or Oval enlargement, with the size about 3~6mm;a nerve root and stem displayed strips and smooth edge, with the size about 2~5mm, nerve Festival signal is more than the nerve root and stem. There was no significant statistical difference with the comparability between the obtained data and autopsy ones. Conclusion:MRN can clearly show lumbar plexus and major branches; its measured value can reflect changes in lumbar plexus. It is possible for diagnostic criteria of the lumbar plexus nerve diseases and dysplasia.

The Value of MRI in Diagnosis of Peripheral Nerve Disorders

OBJECTIVE: The development of magnetic resonance neurography(MRN) has made it possible to produce high-resolution images of peripheral nerves themselves, as well as associated intraneural and extraneural lesions. We evaluated the clinical application and utility of high-resolution MRN techniques for the diagnosis and treatment of a variety of peripheral nerve disorder(PND)s. MATERIAL AND METHOD: MRN images were obtained using T1-weighted spin echo, T2-weighted fast spin echo with fat suppression, and short tau inversion recovery(STIR) fast spin-echo pulse sequences. Fifteen patients were studied, three with brachial plexus tumors, five with chronic entrapment syndromes, and seven with traumatic peripheral lesions. Ten patients underwent surgery. RESULTS: In MRN with STIR sequences of axial and coronal imagings, signals of the peripheral nerves with various lesions were detected as fairly bright signals and were discerned from signals of the uninvolved nerves. Increased signal with proximal swelling and distal flattening of the median nerve were seen in all patients of carpal tunnel syndrome. Among the eight patients with brachial plexus injury or tumors, T2-weighted MRN showed increased signal intensity in involved roots in five, enhanced mass lesions in three, and traumatic pseudomeningocele in three. Other associated MRI findings were adjacent bony signal change, neuroma, root adhesion and denervated muscle atophy with signal change. CONCLUSION: MRN with high-resolution imaging can be useful in the preoperative evaluation and surgical planning in patients with peripheral nerve lesions.

Magnetic Resonance Neurography with Short Tau Inversion Recovery Sequences for Cervical Radiculopathy

In magnetic resonance(MR) imagings with short tau inversion recovery(STIR) sequences fat signals are specifically suppressed. These imaging techniques, therefore, have been used to identify optic nerve lesions in the orbits, because there are a lot of fat tissues which may obscure the optic nerves in the orbit. The cervical spinal nerves or ventral primary rami of brachial plexus, during their courses in the necks between anterior and middle scalene muscles, are also surrounded by considerable amount of fat deposits. So we used these MR imaging techniques with already used posterior neck coil system, to image cervical spinal nerves directly, and to know whether there are certain signal changes in those nerves of the involved nerve roots, in 12 patients who were considered to have cervical radiculopathies by conventional diagnostic means. In MR neurography with STIR sequences(STIR MRN) of axial and coronal images, signals of the cervical spinal nerves of the involved roots were detected as fairly bright, and were discerned from signals of the spinal nerves of the uninvolved roots. We also measured contrast-to-noise ratio(CNR) of the spinal nerve signals of the involved and uninvolved roots in axial images. The average CNR value of the former was 4.48+/-0.889 and of the latter 1.40+/-0.274. Our fingings indicate that STIR MRNs can be helpful in limiting the lesions more accurately and in making surgical decisions for cervical radiculopathies caused by multileveled discs or spondylosis.