- Email: [email protected]
MRI of the brachial plexus: A review of 51 cases
Computerized Medrcol Imaging and Graphrcs. Printed in the U.S.A. All rights reserved.
Vol. 17, No. I, pp. 45-50,
I
1993 Copyright
MRI OF THE BRACHIAL
PLEXUS:
A REVIEW
0895-61 l/93 $6.00 + .W C 1993 Pergamon Press Ltd.
OF 51 CASES
Hans J. de Verdier*, Patrick M. Colletti+$, and Michael R. Terkt *Department of Diagnostic Radiology, St. G&an Hospital, Stockholm, Sweden; +Department of Radiology, University of Southern California School of Medicine, LAC/USC Imaging Science Center, Los Angeles, CA (Received 9 July 1992: Revised IO Nooemhcr 1992) Abstract-We present a magnetic resonance imaging (MRI) study in 51 patients where the brachial plexus was evaluated. Using a 1.5 T clinical imaging system, we obtained Tl-weighted sequences, and double-echo (intermediateand TZ-weighted) spin-echo images. The coronal plane was imaged in all examinations and was supplemented b) images in the sagittal and/or axial planes. Twenty cases had proven pathological brachial plexus involvement, whereas, in 31 cases, no brachial plexus involvement was present. In 4 cases, the MRI findings were not in agreement with the final diagnosis found in the charts. Key Words: MRI, Brachial plexus, Diagnosis, Clinical imaging, Tissue signal intensit)
INTRODlJCTION
symptoms, and nerve conduction/electromyography (NC/EMG) test results. One case was excluded because of insufficient follow-up. MRI was performed from the cervical spine through the axilla in all cases. Seventeen of these also included axial and sagittal images of the cervical spine and the spinal canal. Using a 1.5 T clinical imaging system Philips Gyroscan S- 15HP (Shelton, CT) we obtained T 1-weighted (TR 262-9 13/TE 15-22), proton density-weighted (TR 1800-2660/TE 19-30), and T2-weighted (TR 18002660/TE 80) spin-echo images. The corona1 plane was imaged in all examinations, and supplemented by images in the sagittal and/or axial planes. The body coil was used in all cases. Two patients were also examined using surface coils. The field of view (FOV) in the coronal plane had a range of 250-500 mm, in the sagittal plane 220-480 mm, and in the axial plane 220-450 mm. For the surface coils, we used a FOV of 200-250 mm. The number of signal averages ranged from 2 to 8, with a slice thickness range of 5- 10 mm, a slice gap of 2-4 mm, and matrix 128-204 X 256. Flow compensation was used in all long TR, long TE examinations.
The brachial plexus has always been a difficult area to image because of its complexity, and the lack of good imaging methods (1, 2, 4-6). The brachial plexus is oriented in an oblique fashion in the corona1 plane, where the superior parts are more anterior than the inferior parts because of the lordotic curve of the cervical spine. The nerve rami, originating from the cervical spine, spread out like a fan, and together between the anterior and middle scalene muscles into the supraclavicular fossa, where they follow and surround closely the subclavian artery through the axilla (3-7). Although computerized tomography (CT) has been the most widely used imaging method thus far, CT has several significant limitations, such as streak artifacts from bone, a single imaging plane capability, and the lack of good soft-tissue differentiation. In this study, we review our experience using magnetic resonance imaging (MRI) as a diagnostic tool in the area of the brachial plexus. MATERIALS
AND
METHODS
From September 1989 through October 1991, 52 patients were evaluated with MRI for suspected pathologic involvement of the brachial plexus. The charts and surgical pathology reports were reviewed and compared with the MRI reports. In the charts, we looked for subjective symptoms and objective findings at clinical neurological examination, persistence of
RESULTS Among the 5 1 cases where sufficient follow-up was possible (Table 1), 19 positive MRI reports were confirmed as having pathologic involvement of the brachial plexus (Table 2), and 28 were confirmed as normal in accordance with the MRI results (Table 3). Three main categories were established: neoplasms (Figs. l-3), trauma (Fig. 4), and a miscellaneous group with unspecified radiating pain.
t Correspondence should be addressed to: Dr. Patrick Colletti, LAC/USC Imaging Science Center. I744 Zonal Avenue, Los Angeles, CA 90033. 45
46
Computerized Medical Imaging and Graphics
Table 1. Total study population
Diagnosis
Number of cases: pos/neg
Total n. cases/each group
Neoplasm: Breast carcinoma Lung carcinoma Malignant melanoma Adenocarcinoma, unknown Osteosarcoma Desmoid Soft tissue sarcoma Rhabdomyosarcoma Colon carcinoma Germ cell carcinoma Lymphoma Adenocarcinoma, gastric Squamous cell carcinoma, cervix Trauma Radiating pain, unspecified
16114 5104 5103 l/O1 l/ l/ 11 11 11 02 01 01 01 01 2103 2114
30 9 8 2
Totals
2013 1
51
1 I I
I 1 2 1 1 1
1 5 16
One patient with breast cancer metastasis in the area of the brachial plexus was considered, on the MRI examination, to be positive. The follow-up showed arm edema and pain, but no proven neuropathy. Re-evaluation of the MRI examination showed a fat plane between the lesion and the neurovascular bundle on the sagittal images. Another patient was imaged after breast cancer treatment, and was reported negative with a reservation because of numerous artifacts around
Table 2. Study population Diagnosis 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Il. 12. 13. 14. IS. 16. 17. 18.
Breast carcinoma Breast carcinoma Breast carcinoma Breast carcinoma Breast carcinoma Lung carcinoma Lung carcinoma Lung carcinoma Lung carcinoma Lung carcinoma Adenocarcinoma unknown Malignant melanoma Desmoid Osteosarcoma Soft tissue sarcoma Rhabdomyosarcoma Trauma with hematoma Trauma with hematoma and nerveroot avulsions 19. Radiating pain, unspecified 20. Radiating pain, unspecified
January-Februaryll993,
Volume 17, Number 1
metallic clips. Even at re-evaluation, the artifacts obscured the area to such a degree that it was very hard to determine whether there was any pathologic involvement. Two patients, positive based on NC/EMG tests and physical examination, exhibited no pathology with MRI examination, even in retrospect. Both had nerve involvement distal to the brachial plexus (probably outside the FOV). Among the patients who had no brachial plexus involvement on both the MRI reports and the follow-up, we found, in 19 cases, a final diagnosis as reported in Table 3. In our retrospective study, neoplasms were the majority with 59% (30 of 5 1) of the total population, and 80% ( 16 of 20) of the population with clinical evidence for involvement of the brachial plexus. Trauma represented 10% (6 of 5 1) and 10% (3 of 20) respectively, while the group with unspecified radiating pain comprised 3 1% (16 of 5 1) of the total population, but only 10% (2 of 20) of the second group. DISCUSSION MRI has replaced CT in the evaluation of the brachial plexus. The neurovascular bundle in the supraclavicular region is usually surrounded by fat, which contrasts very well with the lower signal intensity (SI) of the nerves, vascular structures, muscles, and most pathologic changes on the Tl-weighted images. (6) In
with brachial
plexus involvement
MRI signal characteristics Tl=M4F;T2>MM=F TI>M+F;T2+M>F Tl>M~F,T2$M>F Tl=MQF;T2%M=F TI =MF TI=M<.F;T2+M=F TI=MMF TI =MeF;T2>MM~F;T2$M>F Tl=MF TlF TIF
Pathology location L thoracic apex R thoracic apex R thoracic apex R thoracic apex R thoracic apex R thoracic apex R thoracic apex L thoracic apex R thoracic apex R thoracic apex R neck L supraclavicular region + axilla L neck R proximal humerus L axilla L axilla R supraclavicular region R supraclavicular region + spinal cord R disc protrusion with equivocal cord indentation mild cervical degenerative changes, no obvious root compression
M = muscle; F = fat; > indicates increased intensity; %,, markedly increased intensity; <, decreased intensity; +, markedly decreased intensity; = indicates no change in intensity: R = right; L = left.
Fig. 1. Patient #l 1 in Table 2. The patient has had surgery in the right lower side of the neck where artifacts from metallic clips are seen on both images (black straight arrows). (a) Coronal proton density-weighted (TR 1800/TE 30) image demonstrates the right brachial plexus (black arrowheads) peripheral to the neck mass. (b) Axial T2weighted (TR 1800/TE 80) image demonstrates the recurrent adenopathy (white curved arrow) posterior to the artifacts of the clips, and the brachial plexus distal to that (black curved arrow).
Fig. 2. Patient #I 3 in Table 2. (a) Coronal Tl-weighted (TR 555/TE 15) image demonstrates the proximal lower brachial plexus (white straight arrows) running inferior to, and compressed caudally by the recurrent tumor. (b) Coronal Tlweighted image after intravenous gadolinium-DTPA reveals the nerves forming the superior part of the brachial plexus entrapped by the tumor (black straight arrows). (c) Axial T Iweighted image after gadolinium-DPTA demonstrates the left exiting nerveroot disappearing into the tumor (white curved arrow).
48
Computerized Medical Imaging and Graphics
January_February/l993,
Volume 17, Number 1
Fig. 3. Patient # I5 in Table 2. (a) Coronal T l-weighted (TR
655/TE 18) image shows the neurovascular bundle (black straight arrows) elevated by the tumor. It is difficult to determine if the tumor infiltrates the plexus. (b) Axial proton density-weighted (TR 1800/TE 18) image demonstrates the subclavian artery close to the tumor (white straight arrow), but this view still does not answer the question of infiltration. (c) Sag&al Tl-weighted image indicates there may be a fatplane between the tumor and the plexus (white curved arrow). The subclavian artery (black curved arrow) and the cords of the plexus (black arrowhead) are seen.
our study, we found all pathology to be of an SI close to muscle (Table 2) in this sequence. On TZweighted images, the SI of pathologic processes ranged from isointense to muscle (which is hypointense in signal) through hyperintense to fat (which is intermediate in SI). Neural tissue remains of low SI on both these sequences. All three positive breast cancer patients who had undergone treatment in the past, showed masses isointense to muscle on all sequences, which were most likely fibrosis and scarring ( 1,4). The use of gadolinium in these patients (Fig. 2) may have helped to separate fibrosis from recurrent tumor (1) although either may enhance considerably. More experience will be necessary to clarify this issue (8). In Table 2, MRI signal characteristics are lacking in the two last patients be-
cause they only have pathologic changes in the cervical spine. We found it appropriate to use images in the coronal plane with a larger FOV (350-450 mm), thickness S-10 mm, and were directed by the location of the pathology we found. In our experience, the axial plane is very useful in the neck where the nerve rami can be identified. The sagittal views have an advantage in the superclavicular and axillary regions, where they display the neurovascular bundle in cross section, and thereby, the relationship to the surrounding soft tissues is best seen. Oblique coronal views aligned with the brachial plexus might also be useful. Rapoport et al. ( 1), and Blair et al. (5) indicate the same experience with the axial and sag&al views, but
MRI of the brachial plexus
??
H. J.
DE VERDIER, P. M. COLLETTI, and M. R. TERK
Fig. 4. Patient #I 8 in Table 2. (a) Axial Tl-weighted (’ TR 470/TE 18) image demonstrates a mass with the same SI as cerebrospinal fluid (CSF) in the left neural foramen (white straight arrows). The right exiting nerve root can be found (white curved arrow), but not the left. (b) Axial T2-weighted gradient echo (TR 562/TE 18/Flip angle 15) image demonstrates the missing left nerve root, the CSF filled pseudomeningocele, and the irregular shape of the left margin of the dural sac (black straight arrows).
they did not emphasize the coronal plane to the same degree. Som and Bergeron (4) hold the opinion that coronal MR images are ideal because they are acquired in the plane of the plexus. We suggest that the importance of the coronal views is not only to give information about the relationship between a pathologic process and the brachial plexus neurovascular bundle, but also to demonstrate the lesion extension into other surrounding areas. In conclusion, we find MRI well suited to evaluate suspected pathology in the region of the brachial plexus. In our experience, the neural structures of the brachial
Table 3. Study population Diagnosis
with no brachial
plexus involvement Final diagnosis
Number of cases
Breast carcinoma Lung carcinoma
4 3
Colon carcinoma
2
Melanoma Adrenocarcinoma gastric Squamous cell carcinoma, cervix Germ cell carcinoma Lymphoma Trauma Radiating pain, unspecified
plexus are best visualized on T 1- and proton densityweighted images because they provide the greatest contrast in signal difference between lesion and surrounding tissue. Pathological lesions were best appreciated on T 1- and T2-weighted images in all cases. We found images in the coronal plane useful for evaluation of possible brachial plexus involvement and determination of extention of the pathological process into surrounding areas. Axial images are primarily used to show the single nerve rami in the neck and the sagittal images to demonstrate the neurovascular bundle and the surrounding area in cross-section.
14
all arm edema and pain 2 brain and C-spine mets 1 distal nerve involvement 1 subclavian and brachiocephalic vein occlusions 1 discbulge C5-6, 6-7, mild spinal canal stenosis C6-7 shoulder skin graft, axillar adenopathy C-spine and supraclavicular mets metastasis of the clavicle
1 subclavian artery occlusion 1 distal nerve involvement 2 AIDS, 1 multiple sclerosis, I depression, 1 thoracic outlet syndrome
Note. C = cervical, AIDS = acquired immunodeficiency syndrome, mets = metastasis.
50
Computerized Medical Imaging and Graphics
SUMMARY
Magnetic resonance imaging (MRI) was performed at 1.5 T in 5 1 patients with suspected brachial plexus lesions. Short TR, TE and long TR, short and long TE sequences were acquired in the coronal plane, with supplemental images in the sagittal and/or axial plane. Coronal images with a large field of view (35-45 cm) were helpful to survey the entire brachial plexus. In the neck, the axial view demonstrates single nerve rami. Sagittal views were more useful in the supraclavicular and axillary regions where they show the neurovascular bundle in cross section along with its relationship to surrounding tissue. Neoplasm was the most common brachial plexus lesion with 16 positive cases. Two cases of brachial plexus neuroma were positive. Two patients with nonspecific radiating pain had cervical spine degenerative disease. MRI is well-suited to evaluate suspected pathology in the region of the brachial plexus. The coronal view is most useful for localization of brachial plexus lesion.
Acknowledgments-This study was supported in part by grants from the Swedish Society of Medicine, and from Mediplast AB, Sweden.
REFERENCES 1. Rapoport, S.; Blair, D.N.; McCarthy, S.M.; Desser, T.S.; Hammers, L.W.; Sostman, H.D. Brachial plexus: Correlation of MR imaging with CT and pathologic findings. Radiology 167:16 I165; 1988. 2. Kneeland, J.B.; Kellman, G.M.; Middleton, W.D.; Cates, J.D.; Jesmanowicz, A.; Froncisz, W.; Hyde, J.S. Diagnosis of diseases of the supraclavicular region by use of MR imaging. AJR 148: 1149-I 151; 1987. 3. Castagno, A.A.; Shuman, W.P. MR imaging in clinically suspected brachial plexus tumor. AJR 149:1219-1222; 1987. 4. Som, P.M.; Bergeron, R.T., eds. Head and neck imaging, 2nd ed. St. Louis: Mosby Year Book; 1991:519;582-591. 5. Blair, D.N.; Rapoport, S.; Sostman, H.D.; Blair, O.C. Normal brachial plexus: MR imaging. Radiology 165:763-767; 1987. 6. Kellman, G.M.; Kneeland, J.B.; Middleton, W.D.; Cates, J.D.; Pech, P.; Grist, T.M.; Foley, W.D.; Jesmanowicz, A. Froncisz, W.; Hyde, J.S. MR imaging of the supraclavicular region: Normal anatomy. AJR 148:77-82; 1987.
January-February/
1993, Volume 17, Number 1
7. Agur, A.M.R. Grants atlas of anatomy, 9th ed. Baltimore: Williams & Wilkins; 1984:377, 555. 8. Webb, W.R.; Sostman, H.D. MR imaging of thoracic disease: Clinical uses. Radiology 182:62I-630; 1992.
About the Author-HANS JAN HELMERDE VERDIERcompleted his college examination in 1976 at Enskilda Gymnasiet in Stockholm, and his medical education and examination at the Karolinska Institute also in Stockholm, in 1983. During his latter years at the institute, Dr. de Verdier served in the departments of geriatrics at both the Danderyds Hospital and at the Solberga Hospital. In 1984, he began a two-year internship at the Central Hospital in V&eras, earning his medical license in 1986. Following his general practice at Upplands V&by, he returned to geriatrics at Stockholm Hospital in 1986. This was followed by 4 years of radiology residency at St. Goran Hospital, Stockholm, which included a half year in radiology at St. Goran Childrens Hospital, and another half year in St. Goran’s department of clinical pathology. Following this, Dr. de Verdier performed a year’s fellowship in magnetic resonance imaging at the Los Angeles County/University of Southern California Imaging Science Center. He has since returned to St. Goran and is now board certified in radiology. About the Author-PATRICK M. COLLETTIreceived a B.S. degree in chemical engineering from Rutgers University, where he continued his studies to receive the M.M.S. in 1971, and the M.D. in 1975 from the Rutgers Medical School. Dr. Colletti completed a surgery internship at the Los Angeles County/University of Southern California Medical Center in 1976. This was followed by a residency in diagnostic radiology, and a fellowship in nuclear medicine. Since 1980, he has held academic appointments with the USC School of Medicine as well as staff physician status with the LAC/USC Medical Center. Presently, he holds the rank of associate professor of radiology with the USC School of Medicine, and is the director of magnetic resonance imaging and spectroscopy for the LAC + USC Medical Center. He is also serving as the medical director for the LAC/USC Imaging Science Center.
About the Author-MICHAEL R. TERK graduated in physiology from the University of California at Berkeley, and then from the medical school at the University of Wisconsin at Madison. He completed an internship and residency at LAC + USC Medical Center, where he served as resident supervisor. He has also studied ultrasound, completed a visiting fellowship in interventional radiology, and a l-year fellowship in magnetic resonance imaging. Dr. Terk has been a staff radiologist and attending physician with the Southern California Permanente Medical Group. He has been on the staff, or served as director of radiology in several San Fernando Valley private hospitals (Van Nuys, Encino, and Canoga Park). For 20 years, Dr. Terk has held academic appointments as instructor and clinical professor with the USC School of Medicine. Currently serving as chief of clinical operations, and as chief of magnetic resonance spectroscopy at the LAC/ USC Imaging Science Center, Dr. Terk is an MRI specialist with the USC University Hospital, and a consultant for magnetic resonance to the Orthopaedic Spine Service at the LAC + USC Medical Center.
Vol. 17, No. I, pp. 45-50,
I
1993 Copyright
MRI OF THE BRACHIAL
PLEXUS:
A REVIEW
0895-61 l/93 $6.00 + .W C 1993 Pergamon Press Ltd.
OF 51 CASES
Hans J. de Verdier*, Patrick M. Colletti+$, and Michael R. Terkt *Department of Diagnostic Radiology, St. G&an Hospital, Stockholm, Sweden; +Department of Radiology, University of Southern California School of Medicine, LAC/USC Imaging Science Center, Los Angeles, CA (Received 9 July 1992: Revised IO Nooemhcr 1992) Abstract-We present a magnetic resonance imaging (MRI) study in 51 patients where the brachial plexus was evaluated. Using a 1.5 T clinical imaging system, we obtained Tl-weighted sequences, and double-echo (intermediateand TZ-weighted) spin-echo images. The coronal plane was imaged in all examinations and was supplemented b) images in the sagittal and/or axial planes. Twenty cases had proven pathological brachial plexus involvement, whereas, in 31 cases, no brachial plexus involvement was present. In 4 cases, the MRI findings were not in agreement with the final diagnosis found in the charts. Key Words: MRI, Brachial plexus, Diagnosis, Clinical imaging, Tissue signal intensit)
INTRODlJCTION
symptoms, and nerve conduction/electromyography (NC/EMG) test results. One case was excluded because of insufficient follow-up. MRI was performed from the cervical spine through the axilla in all cases. Seventeen of these also included axial and sagittal images of the cervical spine and the spinal canal. Using a 1.5 T clinical imaging system Philips Gyroscan S- 15HP (Shelton, CT) we obtained T 1-weighted (TR 262-9 13/TE 15-22), proton density-weighted (TR 1800-2660/TE 19-30), and T2-weighted (TR 18002660/TE 80) spin-echo images. The corona1 plane was imaged in all examinations, and supplemented by images in the sagittal and/or axial planes. The body coil was used in all cases. Two patients were also examined using surface coils. The field of view (FOV) in the coronal plane had a range of 250-500 mm, in the sagittal plane 220-480 mm, and in the axial plane 220-450 mm. For the surface coils, we used a FOV of 200-250 mm. The number of signal averages ranged from 2 to 8, with a slice thickness range of 5- 10 mm, a slice gap of 2-4 mm, and matrix 128-204 X 256. Flow compensation was used in all long TR, long TE examinations.
The brachial plexus has always been a difficult area to image because of its complexity, and the lack of good imaging methods (1, 2, 4-6). The brachial plexus is oriented in an oblique fashion in the corona1 plane, where the superior parts are more anterior than the inferior parts because of the lordotic curve of the cervical spine. The nerve rami, originating from the cervical spine, spread out like a fan, and together between the anterior and middle scalene muscles into the supraclavicular fossa, where they follow and surround closely the subclavian artery through the axilla (3-7). Although computerized tomography (CT) has been the most widely used imaging method thus far, CT has several significant limitations, such as streak artifacts from bone, a single imaging plane capability, and the lack of good soft-tissue differentiation. In this study, we review our experience using magnetic resonance imaging (MRI) as a diagnostic tool in the area of the brachial plexus. MATERIALS
AND
METHODS
From September 1989 through October 1991, 52 patients were evaluated with MRI for suspected pathologic involvement of the brachial plexus. The charts and surgical pathology reports were reviewed and compared with the MRI reports. In the charts, we looked for subjective symptoms and objective findings at clinical neurological examination, persistence of
RESULTS Among the 5 1 cases where sufficient follow-up was possible (Table 1), 19 positive MRI reports were confirmed as having pathologic involvement of the brachial plexus (Table 2), and 28 were confirmed as normal in accordance with the MRI results (Table 3). Three main categories were established: neoplasms (Figs. l-3), trauma (Fig. 4), and a miscellaneous group with unspecified radiating pain.
t Correspondence should be addressed to: Dr. Patrick Colletti, LAC/USC Imaging Science Center. I744 Zonal Avenue, Los Angeles, CA 90033. 45
46
Computerized Medical Imaging and Graphics
Table 1. Total study population
Diagnosis
Number of cases: pos/neg
Total n. cases/each group
Neoplasm: Breast carcinoma Lung carcinoma Malignant melanoma Adenocarcinoma, unknown Osteosarcoma Desmoid Soft tissue sarcoma Rhabdomyosarcoma Colon carcinoma Germ cell carcinoma Lymphoma Adenocarcinoma, gastric Squamous cell carcinoma, cervix Trauma Radiating pain, unspecified
16114 5104 5103 l/O1 l/ l/ 11 11 11 02 01 01 01 01 2103 2114
30 9 8 2
Totals
2013 1
51
1 I I
I 1 2 1 1 1
1 5 16
One patient with breast cancer metastasis in the area of the brachial plexus was considered, on the MRI examination, to be positive. The follow-up showed arm edema and pain, but no proven neuropathy. Re-evaluation of the MRI examination showed a fat plane between the lesion and the neurovascular bundle on the sagittal images. Another patient was imaged after breast cancer treatment, and was reported negative with a reservation because of numerous artifacts around
Table 2. Study population Diagnosis 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Il. 12. 13. 14. IS. 16. 17. 18.
Breast carcinoma Breast carcinoma Breast carcinoma Breast carcinoma Breast carcinoma Lung carcinoma Lung carcinoma Lung carcinoma Lung carcinoma Lung carcinoma Adenocarcinoma unknown Malignant melanoma Desmoid Osteosarcoma Soft tissue sarcoma Rhabdomyosarcoma Trauma with hematoma Trauma with hematoma and nerveroot avulsions 19. Radiating pain, unspecified 20. Radiating pain, unspecified
January-Februaryll993,
Volume 17, Number 1
metallic clips. Even at re-evaluation, the artifacts obscured the area to such a degree that it was very hard to determine whether there was any pathologic involvement. Two patients, positive based on NC/EMG tests and physical examination, exhibited no pathology with MRI examination, even in retrospect. Both had nerve involvement distal to the brachial plexus (probably outside the FOV). Among the patients who had no brachial plexus involvement on both the MRI reports and the follow-up, we found, in 19 cases, a final diagnosis as reported in Table 3. In our retrospective study, neoplasms were the majority with 59% (30 of 5 1) of the total population, and 80% ( 16 of 20) of the population with clinical evidence for involvement of the brachial plexus. Trauma represented 10% (6 of 5 1) and 10% (3 of 20) respectively, while the group with unspecified radiating pain comprised 3 1% (16 of 5 1) of the total population, but only 10% (2 of 20) of the second group. DISCUSSION MRI has replaced CT in the evaluation of the brachial plexus. The neurovascular bundle in the supraclavicular region is usually surrounded by fat, which contrasts very well with the lower signal intensity (SI) of the nerves, vascular structures, muscles, and most pathologic changes on the Tl-weighted images. (6) In
with brachial
plexus involvement
MRI signal characteristics Tl=M4F;T2>M
Pathology location L thoracic apex R thoracic apex R thoracic apex R thoracic apex R thoracic apex R thoracic apex R thoracic apex L thoracic apex R thoracic apex R thoracic apex R neck L supraclavicular region + axilla L neck R proximal humerus L axilla L axilla R supraclavicular region R supraclavicular region + spinal cord R disc protrusion with equivocal cord indentation mild cervical degenerative changes, no obvious root compression
M = muscle; F = fat; > indicates increased intensity; %,, markedly increased intensity; <, decreased intensity; +, markedly decreased intensity; = indicates no change in intensity: R = right; L = left.
Fig. 1. Patient #l 1 in Table 2. The patient has had surgery in the right lower side of the neck where artifacts from metallic clips are seen on both images (black straight arrows). (a) Coronal proton density-weighted (TR 1800/TE 30) image demonstrates the right brachial plexus (black arrowheads) peripheral to the neck mass. (b) Axial T2weighted (TR 1800/TE 80) image demonstrates the recurrent adenopathy (white curved arrow) posterior to the artifacts of the clips, and the brachial plexus distal to that (black curved arrow).
Fig. 2. Patient #I 3 in Table 2. (a) Coronal Tl-weighted (TR 555/TE 15) image demonstrates the proximal lower brachial plexus (white straight arrows) running inferior to, and compressed caudally by the recurrent tumor. (b) Coronal Tlweighted image after intravenous gadolinium-DTPA reveals the nerves forming the superior part of the brachial plexus entrapped by the tumor (black straight arrows). (c) Axial T Iweighted image after gadolinium-DPTA demonstrates the left exiting nerveroot disappearing into the tumor (white curved arrow).
48
Computerized Medical Imaging and Graphics
January_February/l993,
Volume 17, Number 1
Fig. 3. Patient # I5 in Table 2. (a) Coronal T l-weighted (TR
655/TE 18) image shows the neurovascular bundle (black straight arrows) elevated by the tumor. It is difficult to determine if the tumor infiltrates the plexus. (b) Axial proton density-weighted (TR 1800/TE 18) image demonstrates the subclavian artery close to the tumor (white straight arrow), but this view still does not answer the question of infiltration. (c) Sag&al Tl-weighted image indicates there may be a fatplane between the tumor and the plexus (white curved arrow). The subclavian artery (black curved arrow) and the cords of the plexus (black arrowhead) are seen.
our study, we found all pathology to be of an SI close to muscle (Table 2) in this sequence. On TZweighted images, the SI of pathologic processes ranged from isointense to muscle (which is hypointense in signal) through hyperintense to fat (which is intermediate in SI). Neural tissue remains of low SI on both these sequences. All three positive breast cancer patients who had undergone treatment in the past, showed masses isointense to muscle on all sequences, which were most likely fibrosis and scarring ( 1,4). The use of gadolinium in these patients (Fig. 2) may have helped to separate fibrosis from recurrent tumor (1) although either may enhance considerably. More experience will be necessary to clarify this issue (8). In Table 2, MRI signal characteristics are lacking in the two last patients be-
cause they only have pathologic changes in the cervical spine. We found it appropriate to use images in the coronal plane with a larger FOV (350-450 mm), thickness S-10 mm, and were directed by the location of the pathology we found. In our experience, the axial plane is very useful in the neck where the nerve rami can be identified. The sagittal views have an advantage in the superclavicular and axillary regions, where they display the neurovascular bundle in cross section, and thereby, the relationship to the surrounding soft tissues is best seen. Oblique coronal views aligned with the brachial plexus might also be useful. Rapoport et al. ( 1), and Blair et al. (5) indicate the same experience with the axial and sag&al views, but
MRI of the brachial plexus
??
H. J.
DE VERDIER, P. M. COLLETTI, and M. R. TERK
Fig. 4. Patient #I 8 in Table 2. (a) Axial Tl-weighted (’ TR 470/TE 18) image demonstrates a mass with the same SI as cerebrospinal fluid (CSF) in the left neural foramen (white straight arrows). The right exiting nerve root can be found (white curved arrow), but not the left. (b) Axial T2-weighted gradient echo (TR 562/TE 18/Flip angle 15) image demonstrates the missing left nerve root, the CSF filled pseudomeningocele, and the irregular shape of the left margin of the dural sac (black straight arrows).
they did not emphasize the coronal plane to the same degree. Som and Bergeron (4) hold the opinion that coronal MR images are ideal because they are acquired in the plane of the plexus. We suggest that the importance of the coronal views is not only to give information about the relationship between a pathologic process and the brachial plexus neurovascular bundle, but also to demonstrate the lesion extension into other surrounding areas. In conclusion, we find MRI well suited to evaluate suspected pathology in the region of the brachial plexus. In our experience, the neural structures of the brachial
Table 3. Study population Diagnosis
with no brachial
plexus involvement Final diagnosis
Number of cases
Breast carcinoma Lung carcinoma
4 3
Colon carcinoma
2
Melanoma Adrenocarcinoma gastric Squamous cell carcinoma, cervix Germ cell carcinoma Lymphoma Trauma Radiating pain, unspecified
plexus are best visualized on T 1- and proton densityweighted images because they provide the greatest contrast in signal difference between lesion and surrounding tissue. Pathological lesions were best appreciated on T 1- and T2-weighted images in all cases. We found images in the coronal plane useful for evaluation of possible brachial plexus involvement and determination of extention of the pathological process into surrounding areas. Axial images are primarily used to show the single nerve rami in the neck and the sagittal images to demonstrate the neurovascular bundle and the surrounding area in cross-section.
14
all arm edema and pain 2 brain and C-spine mets 1 distal nerve involvement 1 subclavian and brachiocephalic vein occlusions 1 discbulge C5-6, 6-7, mild spinal canal stenosis C6-7 shoulder skin graft, axillar adenopathy C-spine and supraclavicular mets metastasis of the clavicle
1 subclavian artery occlusion 1 distal nerve involvement 2 AIDS, 1 multiple sclerosis, I depression, 1 thoracic outlet syndrome
Note. C = cervical, AIDS = acquired immunodeficiency syndrome, mets = metastasis.
50
Computerized Medical Imaging and Graphics
SUMMARY
Magnetic resonance imaging (MRI) was performed at 1.5 T in 5 1 patients with suspected brachial plexus lesions. Short TR, TE and long TR, short and long TE sequences were acquired in the coronal plane, with supplemental images in the sagittal and/or axial plane. Coronal images with a large field of view (35-45 cm) were helpful to survey the entire brachial plexus. In the neck, the axial view demonstrates single nerve rami. Sagittal views were more useful in the supraclavicular and axillary regions where they show the neurovascular bundle in cross section along with its relationship to surrounding tissue. Neoplasm was the most common brachial plexus lesion with 16 positive cases. Two cases of brachial plexus neuroma were positive. Two patients with nonspecific radiating pain had cervical spine degenerative disease. MRI is well-suited to evaluate suspected pathology in the region of the brachial plexus. The coronal view is most useful for localization of brachial plexus lesion.
Acknowledgments-This study was supported in part by grants from the Swedish Society of Medicine, and from Mediplast AB, Sweden.
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About the Author-HANS JAN HELMERDE VERDIERcompleted his college examination in 1976 at Enskilda Gymnasiet in Stockholm, and his medical education and examination at the Karolinska Institute also in Stockholm, in 1983. During his latter years at the institute, Dr. de Verdier served in the departments of geriatrics at both the Danderyds Hospital and at the Solberga Hospital. In 1984, he began a two-year internship at the Central Hospital in V&eras, earning his medical license in 1986. Following his general practice at Upplands V&by, he returned to geriatrics at Stockholm Hospital in 1986. This was followed by 4 years of radiology residency at St. Goran Hospital, Stockholm, which included a half year in radiology at St. Goran Childrens Hospital, and another half year in St. Goran’s department of clinical pathology. Following this, Dr. de Verdier performed a year’s fellowship in magnetic resonance imaging at the Los Angeles County/University of Southern California Imaging Science Center. He has since returned to St. Goran and is now board certified in radiology. About the Author-PATRICK M. COLLETTIreceived a B.S. degree in chemical engineering from Rutgers University, where he continued his studies to receive the M.M.S. in 1971, and the M.D. in 1975 from the Rutgers Medical School. Dr. Colletti completed a surgery internship at the Los Angeles County/University of Southern California Medical Center in 1976. This was followed by a residency in diagnostic radiology, and a fellowship in nuclear medicine. Since 1980, he has held academic appointments with the USC School of Medicine as well as staff physician status with the LAC/USC Medical Center. Presently, he holds the rank of associate professor of radiology with the USC School of Medicine, and is the director of magnetic resonance imaging and spectroscopy for the LAC + USC Medical Center. He is also serving as the medical director for the LAC/USC Imaging Science Center.
About the Author-MICHAEL R. TERK graduated in physiology from the University of California at Berkeley, and then from the medical school at the University of Wisconsin at Madison. He completed an internship and residency at LAC + USC Medical Center, where he served as resident supervisor. He has also studied ultrasound, completed a visiting fellowship in interventional radiology, and a l-year fellowship in magnetic resonance imaging. Dr. Terk has been a staff radiologist and attending physician with the Southern California Permanente Medical Group. He has been on the staff, or served as director of radiology in several San Fernando Valley private hospitals (Van Nuys, Encino, and Canoga Park). For 20 years, Dr. Terk has held academic appointments as instructor and clinical professor with the USC School of Medicine. Currently serving as chief of clinical operations, and as chief of magnetic resonance spectroscopy at the LAC/ USC Imaging Science Center, Dr. Terk is an MRI specialist with the USC University Hospital, and a consultant for magnetic resonance to the Orthopaedic Spine Service at the LAC + USC Medical Center.