Incidental Benign Musculoskeletal Findings on PET-CT: an Educational Pictorial Review

Transcription

1 Incidental Benign Musculoskeletal Findings on PET-CT: an Educational Pictorial Review Poster No.: P-0008 Congress: ESSR 2014 Type: Educational Poster Authors: F. Moloney, J. Ryan, M. Twomey, S. McSweeney; Cork/IE Keywords: Musculoskeletal joint, Musculoskeletal bone, Musculoskeletal soft tissue, PET-CT, PET, Staging, Inflammation DOI: /essr2014/P-0008 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 24

2 Learning objectives To illustrate the spectrum of benign musculoskeletal inflammatory conditions detectable on 18F-FDG PET-CT performed for the purpose of staging or restaging malignant disease. Background Combined PET-CT is increasingly performed for the detection and staging of malignant disease owing to the hypermetabolism displayed by malignant cells. Infectious and inflammatory disease, including several inflammatory conditions of the musculoskeletal system have been shown to be 18F-FDG-avid on PET. (1) PET has been shown to be a reliable indicator of disease activity in inflammatory arthropathies especially rheumatoid arthritis with the degree of radiotracer uptake correlating well with clinical symptoms and synovial thickness on ultrasound. (2) Osteoarthritis may or may not exhibit increased radiotracer uptake, depending on the presence or absence of synovitis. (1) Whole-body PET-CT is traditionally performed from the skull base to the mid-thigh, imaging several joints and common sites of extra-articular musculoskeletal disease, and allowing precise anatomical location of any sites of abnormal radiotracer uptake. The purpose of this educational exhibit is to illustrate the spectrum of benign musculoskeletal inflammatory conditions detectable on 18F-FDG PET-CT performed for the purpose of staging or re-staging malignant disease. We performed a retrospective review of all patients presenting to a tertiary referral hospital and regional cancer centre for staging or restaging of malignant disease with PET-CT. The PET-CT was performed in a dedicated PET-CT unit using an integrated PETCT scanner (GE Discovery VCT, GE Healthcare, Buckinghamshire, United Kingdom). Patients fasted for six hours prior to scanning and were asked to refrain from physical activity for 24 hours. Blood glucose levels were verified to be below 8.3 mmol/l. Patients 18 were administered 350 +/- 10% megabecquerels (MBq) of F-FDG intravenously and after 60 minutes of rest, were scanned from the skull base to the mid-thigh level. The scanning time for emission PET was 3 minutes per bed position. Images were reconstructed using iterative reconstruction. A non-contrast CT scan of the thorax, abdomen and pelvis, using a standard protocol (120kV, 80 to 120 ma, slice thickness of 3.75 mm, pitch of 0.98, and a tube rotation Page 2 of 24

3 time of 0.5 seconds per rotation), preceded the PET scan, which was used for diagnostic purposes and for attenuation correction. Imaging findings OR Procedure Details FDG accumulation was commonly encountered at sites of degenerative and inflammatory disease, at both intra- and extra-articular locations. Extra-articular disease included both tendinopathy (inflammation of a tendon and its surrounding sheath/paratendon), enthesopathy (inflammation at the site of tendon or ligament insertion into bone), and bursitis. (3) Acromioclavicular joint The acromioclavicular joint is a small synovial joint that is predisposed to painful syndromes because of mechanical stress or congenital variations. Common pathologies causing pain include osteoarthritis, os acromiale syndrome and distal clavicle osteolysis, which can usually be identified on the CT portion of the PET-CT. However, FDG accumulation at this joint has been found to be frequent and not related to symptoms in other studies. It has a strong age correlation and most likely represents inflammatory synovial proliferation or other chronic inflammatory processes occurring in aging joints. (4) Rotator cuff The rotator cuff muscles supraspinatus, infraspinatus, and teres minor muscles insert at the greater tuberosity of the humerus, while subscapularis inserts at the lesser tuberosity. Focal FDG accumulation can occur adjacent to the tuberosities in the setting of rotator cuff enthesopathy. (5) Spine Degenerative spinal disease is a common incidental finding on PET-CT (22% of patients in one series). Degenerative changes are most prevalent in the lumbosacral spine and can be readily recognized on CT and differentiated from spinal metastatic deposits. The severity of the degree of the PET findings correlates with the severity of degenerative disc and facet disease as graded by CT, likely due to the fact that the inflammation that accompanies degenerative disease is evident on PET. (6) Page 3 of 24

4 Femoral trochanters Greater trochanteric pain syndrome is characterized by focal pain and point tenderness over the greater trochanter with effective relief from steroid or anesthesia injection. The condition must likely relates to tendinopathy of the gluteus medius and minimus tendons with or without accompanying reactive bursitis. The condition is typically unilateral and is more common in middle-aged and elderly women. (7) The bony surface of the greater trochanter consists of four facets: anterior, lateral, posterior, and superoposterior. The gluteus medius muscle attaches to the superoposterior and lateral facets and the gluteus minimus muscle attaches to the anterior facet. The trochanteric bursa covers the posterior facet and the lateral insertion of the gluteus medius muscle. The subgluteus medius bursa is located deep to the gluteus medius tendon. The subgluteus minimus bursa lies in the area of the anterior facet deep to the gluteus minimus tendon and extends medially covering the anterior hip joint capsule. (8). The myofascial attachments and bursae associated with the greater trochanter may be affected by altered lower-limb biomechanics. Osteoarthritis of the lumbar spine, hip, or knee, iliotibial band tightness or tendonitis, or strain of the hip external rotators may contribute to trochanteric pain by adding stress to the region. The iliopsoas muscle inserts at the lesser trochanter and focal FDG accumulation at this point may relate to tendinopathy or iliopsoas bursitis. (9) Ischial tuberosity Ischiogluteal bursitis is an often overlooked cause of buttock pain. The bursa is located between the posteroinferior aspect of the ischial tuberosity and the gluteus maximus muscle. Inflammation of the bursa is often due to chronic and repetitive irritation, often in patients with sedentary lifestyles. Moreover, repetitive trauma in cancer patients with gluteal subcutaneous fat loss can lead to inflammation of the bursa. Irregularity of the cortex of the ischial tuberosity or calcification adjacent to the tuberosity may be present on the CT. (10) (11) Achilles tendon The Achilles tendon is the most commonly injured tendon in the foot and ankle. (12) The Achilles tendon is protected against inflammatory processes because no true synovial sheath is present. However, the Achilles tendon can be secondarily affected by inflammatory processes involving the retrocalcaneal bursa. Furthermore, involvement of the Achilles paratendon has been noted in systemic inflammatory diseases, such as rheumatoid arthritis. (13) FDG accumulation in the tendon and paratendon may occur in Page 4 of 24

5 Achilles paratendinitis, and to a lesser extent in tendinopathy. Chronic tendon thickening or calcification may be evident on the CT. Images for this section: Fig. 2: A corresponding axial CT image of the left acromioclavicular joint shows joint space narrowing consistent with degenerative joint disease. Page 5 of 24

6 Fig. 1: Fused axial PET-CT image shows increased radiotracer uptake at the left acromioclavicular joint with joint space narrowing consistent with degenerative joint disease. Page 6 of 24

7 Fig. 4: A corresponding axial CT image demonstrates degenerative joint disease at the right patellofemoral joint. Fig. 3: Fused axial PET-CT image demonstrates increased radiotracer uptake at the right patellofemoral joint. Page 7 of 24

8 Fig. 15: Aaxial CT image demonstrates degenerative joint disease at the sternoclavicular joints bilaterally. Page 8 of 24

9 Fig. 5: Fused axial PET-CT image shows radiotracer accumulation in the left infrascapular region. Page 9 of 24

10 Fig. 12: Fused coronal PET-CT images demonstrates increased radiotracer uptake in the pectoralis muscles bilaterally in a patient using crutches. Page 10 of 24

11 Page 11 of 24

12 Fig. 7: Fused coronal PET-CT image shows increased radiotracer uptake at the right acromioclavicular joint consistent with degenerative joint disease. increased uptake in the region of the greater tuberosity suggests rotator cuff enthesopathy. Fig. 19: Fused axial PET-CT image shows a focus of eccentric radiotracer uptake at the lateral aspect of the left femoral diaphysis. Page 12 of 24

13 Fig. 17: Fused axial PET-CT image shows radiotracer accumulation at the site of healing left-sided rib fractures. Page 13 of 24

14 Fig. 13: Fused axial PET-CT image shows increased radiotracer uptake at the right glenohumeral joint. Page 14 of 24

15 Fig. 8: Fused coronal PET-CT image shows increased radiotracer uptake at the hip joints bilaterally with degenerative joint disease. Page 15 of 24

16 Fig. 10: Fused coronal PET-CT image demonstrates increased radiotracer uptake at the sacroiliac joints bilaterally suggesting sacroilitis. Page 16 of 24

17 Fig. 9: Fused coronal PET-CT image demonstrates increased radiotracer uptake at the left acromioclavicular joint with degenerative joint disease. Page 17 of 24

18 Fig. 6: A corresponding axial CT image shows fibrous soft tissue stranding in the infraspinatus region. Appearances are consistent with elastofibroma derma. Page 18 of 24

19 Fig. 11: Fused axial PET-CT images demonstrates increased radiotracer uptake in the pectoralis muscles bilaterally in a patient using crutches. Page 19 of 24

20 Fig. 20: Axial CT image demonstrates a focus of cortical sclerosis at the lateral aspect of the femoral diaphysis. Appearances suggest a stress fracture. Fig. 14: Fused axial PET-CT image demonstrates increased radiotracer uptake at the sternoclavicular joints bilaterally with degenerative joint disease. Page 20 of 24

21 Fig. 16: Fused axial PET-CT image demonstrates increased radiotracer uptake iat the left ischial tuberosity consistent with enthesopathy. Page 21 of 24

22 Fig. 18: Fused coronal PET-CT images demonstrates increased radiotracer uptake at the right sternoclavicular joint. Page 22 of 24

23 Conclusion FDG-avid benign musculoskeletal disease is commonly incidentally encountered when interpreting PET-CT performed for the staging of malignant disease. It is imperative that the reporting radiologist be familiar with the spectrum of benign FDG-avid musculoskeletal disease on PET-CT. These conditions can be a source of significant patient morbidity resulting in pain, restricted movement and functional impairment. Benign skeletal radiotracer uptake may simulate osseous metastatic disease in patients with malignancy and knowledge of potential benign sites of uptake related to athropathy or degeneration may prevent misdiagnosis. Furthermore, many of these conditions may represent a diagnostic conundrum for physicians with the diagnosis only becoming clear on the PET-CT. These incidental benign musculoskeletal conditions should be recognized, reported and clinically correlated by the requesting physician. References Musculoskeletal pitfalls in 18F-FDG PET/CT: pictorial review. Costelloe CM,MurphyWAJr, Chasen BA. AJR Am J Roentgenol 2009;193:WS1-WS13. Assessment of disease activity in rheumatoid arthritis with (18)F-FDG PET. Beckers C, Ribbens C, André B, et al. J Nucl Med 2004;45(6): Spectrum of focal benign musculoskeletal 18F-FDG uptake at PET/CT of the shoulder and pelvis. Sopov V, Bernstine H, Stern D, et al. Am J Roentgenol 2009;192(4): Joint accumulations of FDG in whole body PET scans. Von Schulthess GK, Meier N, Stumpe KD. Nuklearmedizin 2001;40(6): Evaluation of shoulder disorders by 2-(F-18)-flouro-2-deoxy glucose positron emission tomography and computed tomography. Moon YL, Lee SH, Park SY, et al. Clin Orthop Surg 2010;2(3) Increased 18F-FDG uptake in degenerative disease of the spine: characterization with 18F-FDG PET/CT. Rosen RS, Fayad L, Wahl RL. J Nucl Med 2006;47(8): Tendinosis and tears of gluteus medius and minimus muscles as a cause of hip pain: MR imaging findings. Kingzett-Taylor A, Tirman PF, Feller J. et al. Am J Roentgenol1999;173(4): Greater trochanter of the hip: attachment of the abductor mechanism and a complex of three bursae--mr imaging and MR bursography in cadavers and MR imaging in asymptomatic volunteers. Pfirrmann CW, Chung CB,TheumannNH, et al. Radiology 2001;221(2): Page 23 of 24

24 Greater trochanteric pain syndrome: epidemiology and associated factors. Segal NA, Felson DT, Torner JC, et al. Arch Phys Med Rehabil 2007;88(8): Non-infectious ischiogluteal bursitis: MRI findings. Cho KH1, Lee SM, Lee YH, et al. Korean J Radiol 2004;5(4): Imaging features of ischial bursitis with an emphasis on ultrasonography. Kim SM, Shin MJ, Kim KS, et al. Skeletal Radiol 2002;31(11): Imaging of the Achilles tendon. Bleakney RR, White LM. Foot Ankle Clin 2005;10(2): MR Imaging of Disorders of the Achilles Tendon. SchweitzerME, Karasick D. Am J Roentgenol 2000;175: Personal Information Page 24 of 24