To review the mechanisms, characteristics and diagnostic roles of fatsuppressed water bright magnetic resonance images such as short tau

Transcription

1 Differential diagnosis of non-neoplastic vertebral and paravertebral disorders with increased signal intensity on short tau inversion recovery (STIR) or fat-suppressed T2weighted images Poster No.: C-1375 Congress: ECR 2018 Type: Educational Exhibit Authors: Y. Miyamoto, S. Takao, N. Kawano, J. Ueno, M. Harada; Tokushima/JP Keywords: Edema, Inflammation, Infection, Diagnostic procedure, MR, Musculoskeletal spine, Musculoskeletal joint DOI: /ecr2018/C-1375 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 25

2 Learning objectives To review the mechanisms, characteristics and diagnostic roles of fatsuppressed water bright magnetic resonance images such as short tau inversion recovery (STIR) or fat-suppressed T2-weighted images (FST2WI). To discuss clinical and radiological features of non-neoplastic vertebral and paravertebral disorders categorized by location of abnormalities with representative clinical images. Page 2 of 25

3 Background Fat-suppressed water bright magnetic resonance images such as STIR or FST2WI offer advantages for detecting abnormalities for musculoskeletal disorders. Also in vertebral and paravertebral regions, STIR and FST2WI improve detection of abnormalities compared with conventional T1- and T2weighted images. Non-neoplastic vertebral and paravertebral abnormalities such as inflammation, infection or acute fracture show high signal intensity on STIR or FST2WI, however, neoplastic disorders often show similar appearances. Therefore, proper differential diagnosis is needed to avoid unnecessary biopsy or surgical procedures. Page 3 of 25

4 Findings and procedure details # FST2WI and STIR ; Brief summary of imaging techniques Fat-suppressed T2-weighted image (FST2WI) and short-tau inversion recovery (STIR) have different acquisition methods, advantages and disadvantages (Table1). Imaging contrasts may differ according to imaging parameters (e.g. echo times) (Fig.1). # Vertebral body lesions 1. Vertebral fracture Clinical features: Wedge compression fracture 1. One type of vertebral fracture resulted from axial loading and hyperflexion often occurs secondary to osteoporosis in elderly patients. Single-column fracture affecting the anterior element of vertebral body, and posterior elements are preserved : wedge-shaped change. 2. Burst fracture One type of vertebral fractures resulted from high energy axial loading injury. Double-column fracture affecting both anterior and posterior elements of vertebral body. Disrupted posterior element of vertebral body may cause bony spinal stenosis. 3. MRI findings: Signal change of FS-T2WI or STIR helps us distinguish acute or old fracture. For about a month after the injury, high intensity signals in vertebral body on FST2WI or STIR (Fig.1-A) which reflect necrosis of the trabecula and reactive osteogenesis are seen. After a month or later, high intensity signal area on FST2WI or STIR in vertebral body decrease and replace to fat signal intensity (: high in T1 and T2WI, low in FST2WI or STIR). Note: Page 4 of 25

5 MRI imaging findings of benign vertebral fracture due to trauma or osteoporosis which differentiate from pathological fracture due to bone tumor (e.g. metastatic bone tumor). Abnormal high intensity signals in bone marrow only in acute phase, but fat intensity in chronic phase. The borderline between abnormal and normal signal intensity often runs parallel to the disk. Low-signal-intensity band parallel to the endplate on T1WI and T2WI suggesting compressed trabeculae (Fig.1-B, C arrow). Cleft-like fluid collection in the vertebral body : fluid sign Gas collection due to negative pressure in the vertebral body : vacuum cleft Decreased signal intensity in opposed phase on chemical shift images suggesting the existence of fatty bone marrow. 2. Intervertebral osteochondrosis Clinical features Degeneration of spine begins from the disks. Disk generations cause signal changes of not only the disks themselves but also endplates and surrounding soft tissue. MRI findings: Modic et al categorized MRI signal in vertebral endplates along with the disk degeneration. Type 1 changes Low signal intensity on T1WI and high signal intensity on FS-T2WI or STIR(Fig.2-A arrow). Hypervascular fibrous tissue in pathological findings(fig.2-a,b,c). Can cause pain or radiculopathy. Type 2 changes High signal intensity on both T1WI and T2WI, low signal intensity on FST2WI or STIR(Fig.2-D arrow). Fatty degeneration in pathological findings(fig.2-d,e,f). Type 3 changes 1. Low signal intensity on T1WI, T2WI, FS-T2WI or STIR. Page 5 of 25

6 2. Osteoblastic sclerosis, the end of degenerate changes in pathological findings(fig.3). Note: These signal intensity changes often appear at lumbar spine especially in the levels of L4/5 and L5/S1. Sometimes these types are coexisted or change in the clinical course(fig.2). 3. Infectious spondylitis 3-1. Pyogenic spondylitis Clinical features: The common organisms are Staphylococcus aureus and streptococcus species. Fungus and organisms of low virulence may also cause infections. In more than half cases the infective organisms are not identified. Children and elderly (50s-60s) are susceptible. Frequently causes in the lumbar spine (especially in the lower lumber spine), followed by thoracic and cervical spine. Hematogeneous spread of bacteria from the outside of the spine is common. Direct invasion or inoculation from nearby infectious source and iatrogenic inoculation may reach the spine. Paravertebral venous plexus (e.g. the Batson's plexus and the pre-vertebral pharyngeal venous plexus) may act as a route of infection. In adults, the infection first arises in the subchondral region adjacent to the intervertebral disc, and then invade the disk, vertebral body, finally affect the paravertebral and epidural space. Whereas in children, the vascular plexus surrounding the growth plate act as a route of infection and cause discitis. MRI findings: FST2WI or STIR are sensitive to detect the abnormalities and the extent of inflammation. Poorly-circumscribed increased signal intensity in vertebral endplate on FST2WI or STIR(Fig.4-A). Blurring of the endplate and bony destruction(fig.4-a,b,carrow). Fluid signals in the intervertebral space. Page 6 of 25

7 Soft tissue mass spreading around the vertebral space (disk, endplate, and psoas major muscle) reflecting the edema and inflammation associated with infection. Note: To distinguish infectious spondylitis from Modic type 1 intervertebral osteochondrosis is clinically important. It is reported that a wellcircumscribed linear high signal intensity band between the normal and affected bone marrow on Diffusion-Weighted Imaging (DWI) suggests Modic type 1 intervertebral osteochondrosis ("claw sign"). In contrast, high signal intensity in the whole vertebral body on DWI, destruction of endplate, and high signal intensity in intervertebral disk on T2WI suggest infectious spondylitis Tuberculous spondylitis Clinical features: Spinal tuberculosis is most common of musculoskeletal tuberculosis. The thoracolumbar transitional levels of vertebral column is most frequently affected. Usually resulted from hematogenous or lymphogenous spread into vertebral bodies. Infection primary occurs in the anterior part of the vertebra and endplate, then destroy of the intervertebral disk space and the adjacent vertebral bodies. Sometimes affect noncontiguous vertebral bodies ("skip lesion"). Destruction of extensive vertebral bodies cause anterior wedging leading to the characteristic angulation and gibbus formation. MRI findings: Increased signal intensity in vertebral endplate on FST2WI or STIR and decreased signal intensity on T1WI, which are similar to pyogenic spondylitis To distinguish tuberculous spondylitis from pyogenic spondylitis these findings are helpful: Infiltration to the intervertebral disk occurs comparatively latter and disks are preserved, as M. tuberculosis doesn't have proteinase. Inflammation involve paravertebral soft tissue and cause abscesses(fig.5-d arrow)with faint clinical sign of infection (cold abscess) Abscess wall is usually thin, and presence of calcification within the abscess is diagnostic feature of spinal tuberculosis. Page 7 of 25

8 4. Hematopoietic bone marrow(red bone marrow) Clinical features: Conversion from hematopoietic bone marrow to fatty bone marrow is induced by various factors such as aging, radiotherapy and chemotherapy. In contrast, anemia, long-distance running, hematopoietic agents like erythropoietin, obesity and smoking are factors of re-conversion to hematopoietic bone marrow. MRI findings: Hematopoietic bone marrow shows increased signal intensity on FST2WI or STIR(Fig.6-A), and decreased signal intensity on T1WI.(Fig.6-B) Hematopoietic bone marrow shows decreased signal intensity in out-ofphase(fig.6-d) compared to in-phase(fig.6-c) on Dixon method suggesting coexistence with fatty bone marrow. No notable abnormalities are found on plain CT or bone scintigraphy. MRI signal pattern noted above sometimes requires differential diagnosis with bone marrow malignancy (e.g. malignant lymphoma, multiple myeloma, and metastatic tumor). Malignant tumor shows diffuse abnormal signal intensity in bone marrow and may cause bone destruction with paravertebral tumor extension. 18F-FDG PET scan shows slightly higher uptake in hematopoietic bone marrow lesions. However, it is reported that a maximum standard uptake value of >3.6 indicates metastatic tumor. 5. SAPHO syndrome Clinical features: A condition of sterile osteitis with skin disorder such as palmoplantar pustulosis. An acronym for the combination of synovitis, acne, pustulosis, hyperostosis and osteitis. Genetic tendency toward developing SAPHO syndrome and autoimmune reaction to Propionibacterium acnes are thought to cause a chronic inflammation. And relation between HLA-B27 has been reported. Diagnostic criteria proposed by Kahn is widely used: Page 8 of 25

9 Chronic recurrent multifocal sterile and axial osteomyelitis, with or without dermatosis Acute, subacute, or chronic arthritis associated with palmoplantar pustulosis, pustulous psoriasis, or severe acne Any sterile osteitis associated with palmoplantar pustulosis, pustulous psoriasis, or sever acne more than one features above are needed for diagnosis. The most commonly affected skeletal site is the anterior chest wall (sternocostal and sternoclavicular joints, 65% to 90%), followed by the spine, sacroiliac joints and long bones. For diagnosis, infectious osteitis, tumoral conditions of the bone and noninflammatory condensing lesions of the bone must be excluded. MRI findings: Radiographic findings of spinal region are as follows: Vertebral corner lesion(fig.7-a,b arrow head): a focal erosion and/or sclerosis at one of the vertebral body corners considered as an primary change of SAPHO syndrome. On MRI, increased signal intensity in anterior part of vertebrae seen on FST2WI or STIR. Nonspecific spondylodiscitis(fig.7-a,b arrow) Osteolytic change Osteosclerosis Ossification of the paravertebral lesion Sacroiliitis Multiple vertebral bodies may be affected. #Posterior element lesion 1. Spondylolysis Clinical features: Stress fracture in a pars interarticularis of the vertebral arch. Associated with significant low back pain in teenagers and young adults, especially in young athletes. Most cases occur in lumbar spine, most commonly affected at L5 (more than 90% of cases), followed by L4. Categorized into early, progressive, or terminal stage by the progress of disease. Page 9 of 25

10 May cause pseudo-arthrosis if normal healing or synostosis is not obtained. Radiographical findings of early and terminal stages - Early stage Transverse fracture line(fig.8-e arrow head)is seen in the pars interarticularis. CT demonstrates fracture extent better than MRI. An oblique axial multi planner reformation (MPR) view parallel to the long axis of the vertebral arch is helpful to identify the fracture line. Fracture line is localized to the lower part of the pars interarticularis, in a case of incomplete fracture. (Fig.8-F arrow head) MRI depicts abnormal signal intensity of bone marrow associated with fracture. Increased bone marrow signal intensity in the pars interarticularis and pedicle is shown on FST2WI or STIR(Fig.8-A, D arrow). Adjacent soft tissue edema and/or inflammation may also be detected. - Terminal stage MRI shows the presence of fluid collection in the pars interarticularis and bone marrow edema caused by the chronic stress, as an increased signal intensity on FST2WI or STIR. CT images shows the dilatation of the fracture line and osteosclerosis. Plain radiographs depicts the fracture line, which is called "a scottie dog with a collar" sign. 2. Facet arthropathy Clinical features: Facet joints 1. Connecting an inferior articular process of upper vertebra and a superior articular process of the lower vertebra. Support and stabilize the spine, and prevent injury by limiting motion in all planes of movement. 2. Facet joint arthritis is caused by aging, stress from repeated movement, degeneration and inflammation. CPPD (calcium pyrophosphate dehydrate) crystal deposition (pseodogout) is one of the causes of facet joint arthritis. Page 10 of 25

11 MRI findings: Increased signal intensity on FST2WI or STIR in the facet joint. May associated with adjacent soft tissue and/or bone marrow abnormal signal intensity corresponding to inflammatory process.(fig.9-a,c arrow head) On routine MRI study, sagittal section must be set enough to include both facet joint for detection facet arthropathy. T2WI is considered to be less sensitive for detecting adjacent soft tissue and bone marrow abnormalities compared with FST2WI or STIR. 3. Interspinous ligamentitis Clinical features: Interspinous ligaments 1. Composed of thin membranous ligaments connecting the spinous processes from the roots to apexes. Most broad and thick in the lumbar region, and slightly developed in the neck region. 2. Damages and degeneration of interspinous ligament is caused by hyperflexion, degeneration of intervertebral disks, and disk herniation. MRI findings: Abnormal increased intensity signal is found on FST2WI or STIR between spinous processes (Fig.10), suggesting degeneration or damages of interspinous ligaments. Sagittal section may be appropriate for detection. May difficult to detect with non-fat suppressed T2WI. Abnormal signal changes in the lumbar interspinous ligament are commonly detected at the levels of L4/5 or L5/S1. For one of this reason, supraspinous ligament are commonly defect below L4 anatomically. Page 11 of 25

12 Images for this section: Table 1: Fat-suppressed T2-weighted image (FST2WI) and short-tau inversion recovery (STIR); methods, advantages and disadvantages. Radiology, Tokushima University Hospital - Tokushima/JP Page 12 of 25

13 Fig. 1: STIR sagittal images with various TEs. A healthy 20s-year-old man. STIR sagittal images of lumbar spine with 3 different echo times (TEs) at the same window wedge/ level settings. The setting of TE affects the contrast of images. The signal intensity of muscle and subcutaneous fat are relatively low when TE is set longer. Radiology, Tokushima University Hospital - Tokushima/JP Fig. 2: Representative case of acute vertebral fracture (wedge compression fracture). A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image. 70s-year-old woman. A wedge-shaped change is shown in the vertebral body in lower thoracic spine. The bone marrow signal intensity is high on STIR (A), low on T1WI (B), mixed signal intensity on T2WI (C). Each sequence shows low signal intensity line in the vertebra, reflecting the compressed trabeculae (A, B, C arrow). Radiology, Tokushima University Hospital - Tokushima/JP Page 13 of 25

14 Fig. 3: Representative case of intervertebral osteochondrosis (Modic type1 and type2). A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image D: STIR sagittal image, E: T1WI sagittal image, F: T2WI sagittal image. 50s-year-old man. A-C: initinal exam. D-F: 18-month later. The initial exam (A-C) shows narrowing of the intervertebral disk space narrowing with high signal intensity on STIR in the endplates (A arrows). This area shows low signal intensity on T1WI (B arrows) and high signal intensity on T2WI (C arrows), suggesting Modic type 1 endplate changes. 18-month later (D-F), fatty degeneration of bone marrow is found, suggesting shift to Modic type2 change (D, E, F arrows). Partially-remained bone marrow edema is depicted as high signal intensity on STIR (D arrowhead). Radiology, Tokushima University Hospital - Tokushima/JP Page 14 of 25

15 Fig. 4: Representative case of intervertebral osteochondrosis (Modic type3). A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image, D: plain radiograph with lateral view. 70s-year-old man. Narrowing of the intervertebral disk space and decreased signal intensity on each sequence in the bone marrow adjacent to the endplate are seen (A, B, C arrows). Plain radiograph shows osteosclerosis adjacent to the endplates (D arrows). Radiology, Tokushima University Hospital - Tokushima/JP Fig. 5: Representative case of pyogenic spondylitis. A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image. 50s-year-old man. MRI images shows narrowing of the intervertebral disk space and ill-defined bone destruction in the level of L4/5 (A-C arrows). The bone marrow signal is diffusely depicted as high on STIR (A) and T2WI (C), Page 15 of 25

16 and low on T1WI (B). STIR image also visualize edema and/or inflammation of adjacent paravertebral soft tissue (A arrowheads). Radiology, Tokushima University Hospital - Tokushima/JP Fig. 6: Representative case of tuberculous spondylitis. A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image, D: STIR coronal image, E: plain CT image. 50syear-old woman. MRI images shows fluid collection in the intervertebral disk space at the level of L4/5 with bone destruction of adjacent vertebrae. Abscesses are formed beneath the anterior and posterior longitudinal ligaments (A-C arrows) and the right paravertebral space (D arrows). CT image shows the calcifications within the abscess (E arrow). Radiology, Tokushima University Hospital - Tokushima/JP Page 16 of 25

17 Fig. 7: Representative case of hematopoietic bone marrow. A: STIR sagittal image, B: T1WI sagittal image, C: T1WI in-phase image, D: T1WI out-of-phase image. 60s-yearold woman. The bone marrow at the level of L1-L4 shows patchy or geographic high signal intensity on STIR (A), and low signal intensity on T1WI (B). The signal intensity is lower in out-of-phase compared to in-phase images, suggesting benign hematopoietic bone marrow with increased cellularity. In addition, diffuse fatty bone marrow changes are seen in L5 vertebra and sacrum. Radiology, Tokushima University Hospital - Tokushima/JP Page 17 of 25

18 Fig. 8: Representative case of SAPHO syndrome with spinal involvement. A: STIR sagittal image, B: plain CT sagittal image. 50s-year-old woman. STIR image shows high signal intensity in the bone marrow at the vertebral corners (A arrowheads). Erosion of endplates and adjacent abnormal signal intensity in bone marrow are seen which mimic infectious spondylitis (A arrow). CT image shows osteosclerosis and syndesmophyte-like appearance in the anterior part of vertebrae (B arrowheads). Endplate erosions are also seen in CT images (B arrows). Radiology, Tokushima University Hospital - Tokushima/JP Page 18 of 25

19 Fig. 9: Representative case of early-stage spondylolysis. A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image, D: STIR oblique axial image, E: plain CT oblique axial image, F: plain CT sagittal-reformatted image. 10s-year-old man. On MRI, bone marrow signal intensity of both pedicles and pars interartcularis are low on T1WI and high on T2WI (B, C arrow) at the level of L4. STIR visualizes abnormal signals of bone marrow more clearly (A, D arrows). The fracture line is found in the lower aspect of pars interarticularis on CT image (E, F arrowheads), which is depicted as low signal intensity on MRI images (A-D arrowheads). Radiology, Tokushima University Hospital - Tokushima/JP Page 19 of 25

20 Fig. 10: Representative case of cervical facet arthropathy. A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image. 60s-year-old woman. MRI images demonstrate the fluid collection in the facet joint suggesting arthritis. STIR and T1WI visualize bone marrow edema of the anterior and posterior articular processes (A, B arrows). However, the bone marrow signal abnormality is difficult to detect only with T2WI which mimics normal fatty bone marrow. Adjacent soft tissue inflammation and/or edema is also seen with STIR (A arrowhead). Radiology, Tokushima University Hospital - Tokushima/JP Page 20 of 25

21 Fig. 11: Representative case of interspinous ligamentitis. A: STIR sagittal image, B: T1WI sagittal image, C: T2WI sagittal image. 70s-year-old man with low back pain. Increased signal intensity is found on STIR between spinous processes in the levels of L4/5 and L5/ S1 (A arrows). These soft tissue signal abnormality are hardly detected only with T1WI or T2WI (B, C). Radiology, Tokushima University Hospital - Tokushima/JP Page 21 of 25

22 Conclusion The location of increased signal intensity on STIR or FST2WI of vertebral and paravertebral disorders plays an important role to make a precise diagnosis which can lead to appropriate therapy and management. Page 22 of 25

23 Personal information Presentator of this educational exhibition: Yuka Miyamoto Department of Radiology, Tokushima University Hospital, Tokushima, JAPAN Corresponding presentator: Shoichiro Takao Department of Diagnostic Radiology, Graduate School of Health Sciences, Tokushima University, Tokushima, JAPAN Page 23 of 25

24 References Compression fractures: Uetani M, et al : Malignant and benign compression fractures: differentiation and diagnostic pitfalls on MRI. Clin Radiol, 59 : , 2004 Intervertebral osteochondrosis Modic MT, et al : Degenerative disk disease: assessment of changes in vertebral body marrow with MR imaging. Radiology, 166 : , 1988 Modic MT, et al : Degenerative disk disease: assessment of changes in vertebral body marrow with MR imageng. Radiology, 166 : , 2015 Infectious spondylitis Resnick D : Osteomyelitis, Septic Arthritis, and Soft Tissue Infection:Axial Skeleton. Bone and Joint Imaging, 3rd Edition. Elsevier Saunders, PA, , 2005 Patel KB, et al : Diffusion-weighted MRI "claw sign" improves differentiation of infectious from degenerative modic type 1 signal changes of the spine. AJNR Am J Neuroradiol, 35 : , 2014 Garg and Somvanshi : Spinal tuberculosis: A review. J Spinal Cord Med. 34, , 2011 Resnick D : Osteomyelitis, Septic Arthritis, and Soft Tissue Infection:Organisms. Bone and Joint Imaging, 3rd Edition. Elsevier Saunders, PA, , 2005 Hematopoietic bone marrow Shigematsu Y, et al : Distinguishing imaging features between spinal hyperplastic hematopoietic bone marrow and bone metastasis. AJNR Am J Neuroradiol, 35 : , 2014 SAPHO syndrome Kahn MF, Khan MA. The SAPHO syndrome. Baillieres Clin Rheumatol.8: , 1994 Minhchau TN, et al: The SAPHO Syndrome. Seminars in Arthritis and Rheumatism, 42:3; , 2012 Hayem G. SAPHO syndrome. Rev Prat, 54: , 2004 Larendo JD, et al: SAPHO syndrome: MR appearance of vertebral involvement. Radiology. 242(3): , 2007 Spondylolysis Page 24 of 25

25 Sakai T, et al : Characteristics of lumbar spondylolysis in elementary school age children. Eur Spine J, 25 : , 2016 Resnik D : Physical Injury:Spine. Bone and Joint Imaging, 3rd Edition. ELSEVIER SAUNDERS PA, , 2005 Leone A, et al : Lumbar spondylolysis: a review. Skeletal Radiology, 40 : , 2011 Facet arthropathy Steven P, et al : Pathogenesis, Diagnosis, and Treatment of Lumbar Zygapophysial (Facet) Joint Pain. Anesthesiology, 106 : , 2007 Interspinous ligamentitis Fujiwara A, et al : The Interspinous Ligament of the Lumbar Spine. Magnetic Resonance Images and Their Clinical Significance. Spine, 25 : , 2000 Lakadamyali H, et al : STIR sequence for depiction of degenerative changes in posterior stabilizing elements in patients with low back pain. Am J Rentgenol, 191(4), 973-9, 2008 Page 25 of 25