Not everything that's hot on a bone scan is malignant: A pictorial review of benign causes of increased isotope uptake

Transcription

1 Not everything that's hot on a bone scan is malignant: A pictorial review of benign causes of increased isotope uptake Poster No.: C-2190 Congress: ECR 2010 Type: Educational Exhibit Topic: Musculoskeletal Authors: D. E. Moran, A. O'Neill, E. J. Heffernan, S. J. Skehan; Dublin/IE Keywords: Radionuclide Imaging, Benign Bone Lesions, Bone Scintigraphy DOI: /ecr2010/C-2190 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 44

2 Learning objectives To illustrate with examples the common, and some of the less common, benign entities that can produce a positive bone scan. An additional aim is to demonstrate the utility of further imaging (radiography, CT, MRI) in characterising these lesions, reserving percutaneous biopsy for selected cases that remain ambiguous. Background Bone scintigraphy is frequently performed as part of the routine staging of patients with a wide variety of primary malignancies. Although it is a sensitive imaging modality, it is relatively non-specific and there are many potential causes of increased isotope uptake that can mimic metastatic disease. Technique: The procedure is performed with technetium-99m-labelled diphosphonates. The uptake of these radiotracers depicts osteoblastic activity and regional blood flow to bone. By 2-6 hours after injection, about 50% of the injected dose is in the skeletal system and, therefore, delayed static imaging is usually performed at this time using a gamma camera and a low-energy, high-resolution collimator. Page 2 of 44

3 Imaging findings OR Procedure details Benign Causes of Increased Uptake of Radionuclide In this review, the following lesions and patterns of uptake will be discussed: Benign bone lesions Degenerative disease Trauma Infection Superscans Soft tissue uptake Artefacts Benign Bone Lesions Many benign bone lesions demonstrate increased uptake of radionuclide on bone scintigraphy and these include: Fibrous dysplasia (Figures 1 on page 7 and 2 on page 9) Paget disease (Figures 3 on page 9 and 4 on page 11) Enchondroma (Figures 5 on page 11, 6 on page 12 and 7 on page 14) 4. Bone island (Figures 8 on page 15 and 9 on page 15) 5. Haemangioma (Figure 10 on page 17) 6. Osteitis Condensans Ilii (Figures 11 on page 17 and 12 on page 18) 7. Eosinophilic granuloma 8. Melorheostosis 9. Osteoid osteoma 10. Exostosis 11. Pycnodysostosis Page 3 of 44

4 Degenerative Disease Manifests as areas of increased uptake on radionuclide bone scans (Figures 13 on page 19, 16 on page 21 and 17 on page 23). Can be distinguished from metastatic disease by the characteristic location (Figure 14 on page 20 and 15 on page 20): Knees Hands (especially the base of the 1st metacarpal) Wrists Shoulder Both sides of the joint can be involved in arthritis, but this is unusual in malignant disease. Trauma It is possible to distinguish metastatic disease from trauma by analyzing the pattern of distribution of uptake. Rib fractures (Figure 18 on page 23): Multifocal rib trauma has a characteristic linear distribution. Sacral insufficiency fractures (Figure 19 on page 25): The characteristic appearance is that of fracture lines running vertically through both the left and right sacral ala, medial to the SI joints, and a transverse fracture just below the level of the SI joints. The fractures appear as a hot, geographic lesion confined to the sacrum and often have a characteristic "butterfly" or "Honda sign" appearance. Other typical sites for insufficiency fractures include the pubic bones, pubic rami and supra-acetabular region of the iliac bone. Infection Page 4 of 44

5 Classically, on static delayed images, osteomyelitis appears as an area of focally increased bone uptake. Multifocal osteomyelitis can simulate metastatic disease (Figures 20 on page 25,21 on page 27 and 22 on page 27). Three-phase bone scanning is the radionuclide procedure of choice for diagnosing osteomyelitis in bone: st phase = arterial phase, 1 minute post-injection 2nd phase = blood-pool phase, 5 minutes post-injection 3rd phase = static phase, 2 or more hours post-injection Diffuse Symmetrical Increased Uptake ('Superscan') A superscan is defined as a bone scan which demonstrates markedly increased skeletal radioisotope uptake relative to the soft tissues. Non-Malignant Causes of a Superscan: Metabolic Disease: Hyperparathyroidism (Figures 23 on page 28 and 24 on page 29) Hyperthyroidism Renal osteodystrophy Osteomalacia Widespread Bone Lesions: 1. Widespread Paget disease Non-malignant superscans typically demonstrate a uniform pattern of increased uptake, whereas superscans in patients with widespread metastases demonstrate a nonuniform pattern of uptake (Figure 25 on page 30). Soft Tissue Uptake Physiological uptake: Page 5 of 44

6 Kidney Change in location of kidney can be demonstrated incidentally e. g. Horseshoe kidney (Figure 26 on page 32 and 27 on page 34). Bowel If the patient has had surgical diversion of the urinary tract (Figure 28 on page 36) Breast Soft Tissue Uptake Myocardial uptake Can be seen in patients with: Previous myocardial infarction (Figure 29 on page 38) Long-standing congestive heart failure Pericarditis Amyloidosis Unstable angina Post-resuscitation or cardioversion Inflammation Tendinopathy (Figures 30 on page 40 and 31 on page 40) Bursitis Abscess Crystalline arthropathy Radiation Heterotopic ossification Causes increased uptake due to the presence of extraskeletal osteoblasts. Artefacts Medical devices Page 6 of 44

7 Portacath (Figure 32 on page 41) Previous radionuclide procedure Sentinel node injection (Figure 33 on page 42) Images for this section: Page 7 of 44

8 Page 8 of 44

9 Fig. 1: Anterior whole-body bone scintigram demonstrates increased uptake of radionuclide in the right side of the skull base, right humerus, left femur and left tibia (arrows). Fig. 2: 48 year old male (continued from Figure 1). AP radiographs of the left femur, left tibia and right humerus demonstrate lucent, slightly expansile lesions with internal 'ground-glass' matrix in the proximal femoral shaft, mid-shaft of the humerus and distal shaft of the tibia typical of fibrous dysplasia. Page 9 of 44

10 Page 10 of 44

11 Fig. 3: 51 year old female. Anterior (left) and posterior (right) whole-body bone scintigrams demonstrate increased uptake of radionuclide in the sacrum, particularly on the left side (arrows). Fig. 4: 51 year old female (continued from Figure 3). T1-weighted MRI of the sacrum demonstrates marked cortical thickening within the left sacral ala (arrow) consistent with the diagnosis of Paget disease of bone. Page 11 of 44

12 Fig. 5: 49 year old female with a background history of breast cancer. Anterior bone scintigram shows increased isotope uptake in the proximal right humeral shaft (arrow). Page 12 of 44

13 Page 13 of 44

14 Fig. 6: 49 year old female with a background history of breast cancer (continued from Figure 5). AP radiograph of the right humerus demonstrates calcified chondroid matrix within the proximal right humeral shaft (arrow) consistent with an enchondroma. Page 14 of 44

15 Fig. 7: 49 year old female with a background history of breast cancer (continued from Figure 5). Sagittal T2* sequence from an MRI of the right shoulder shows an enchondroma in the neck of the right humerus. There is 'blooming' of the internal calcification on a background of high signal, typical of chondroid matrix. Fig. 8: 59 year old female. Anterior bone scintigram shows minimal increased uptake in the distal shaft of the left femur (arrow). Page 15 of 44

16 Page 16 of 44

17 Fig. 9: 59 year old female (continued from Figure 8). Lateral radiograph of the left knee demonstrates a giant bone island in the distal left femoral shaft (arrow) with the long axis of the sclerotic lesion along the long axis of the femur, as is usually the case with bone islands. The subtle increase in tracer uptake on scintigraphy is explained by the increased volume of dense bone, without any increase in osteoblastic activity. Fig. 10: 71 year old female with a background history of breast cancer. Anterior bone scintigram (left) demonstrates a significant increase of uptake in the body of L1 suspicious for a metastasis. CT was suggestive of a vertebral haemangioma, with vertical spicules of bone in the lesion. However, in view of the increased uptake on bone scintigraphy, CT-guided biopsy (right) was performed, confirming that the lesion was a haemangioma. Haemangiomas are not usually visible on bone scintigraphy, but have rarely been described to cause increased uptake. Page 17 of 44

18 Fig. 11: 55 year old female with a background history of breast cancer. Posterior bone scintigram demonstrates increased uptake of radionuclide in the right ilium adjacent to the right sacro-iliac joint (arrow). Page 18 of 44

19 Fig. 12: 55 year old female with a background history of breast cancer (continued from Figure 11). AP radiograph of the pelvis demonstrates diffuse sclerosis on the iliac side of the right sacro-iliac joint with preservation of the right sacro-iliac joint space consistent with osteitis condensans ilii. Page 19 of 44

20 Fig. 13: Anterior (left) and posterior (right) planar scintigrams of the pelvis demonstrate increased uptake of radionuclide in the weight-bearing (superior) portion of the left acetabulum (arrows) consistent with degenerative disease. Fig. 14: By contrast, in this patient with metastatic involvement of the left acetabulum, anterior (left) and posterior (right) planar scintigrams of the pelvis demonstrates increased uptake of radionuclide throughout the left acetabulum (arrows) consistent with malignant disease. Page 20 of 44

21 Fig. 15: AP radiograph of the left acetabulum in the same patient as figure 14, demonstrates a large lytic lesion in the left acetabulum (arrow) consistent with a bony metastasis. Page 21 of 44

22 Page 22 of 44

23 Fig. 16: Increased uptake is demonstrated within the left greater tuberosity of the humerus and right greater trochanter of the femur (arrows) secondary to degenerative disease at the tendinous insertions of the rotator cuff and hip abductor muscles respectively. Fig. 17: Anterior (left) and posterior (right) planar scintigrams of the cervical spine demonstrate a mid-cervical lateral focus of increased uptake (arrows). Lateral uptake of radionuclide in the cervical spine is invariably benign. Page 23 of 44

24 Page 24 of 44

25 Fig. 18: Rib fractures. Anterior bone scintigram shows markedly increased uptake of radionuclide in a characteristic linear distribution of the anterior 5th to 8th ribs on the left secondary to rib fractures. The increased uptake in the left sacrum and pubic rami bilaterally is due to insufficiency fractures. Fig. 19: Sacral insufficiency fractures. The characteristic 'Honda' sign is demonstrated on the posterior planar scintigram (right, arrow). Multiple other fractures are present within the ribs, pubic rami and mid-thoracic spine in this patient with osteoporosis. Page 25 of 44

26 Page 26 of 44

27 Fig. 20: 28 year old female. Anterior bone scintigram demonstrates increased tracer uptake in the right humeral head and supra-acetabular region of the right iliac bone (arrows). Fig. 21: 28 year old female (continued from Figure 20). Coronal STIR sequence from an MRI pelvis demonstrates high signal within the superior aspect of the right acetabulum which corresponds with the scintigraphic abnormality. The patient had biopsy-proven tuberculous (TB) osteomyelitis. Page 27 of 44

28 Fig. 22: 28 year old female with TB osteomyelitis (continued from Figure 20). Axial T1weighted MRI of the right shoulder with fat-saturation and post- gadolinium demonstrates avid enhancement of the lesion within the proximal right humerus and enhancing axillary adenopathy. Page 28 of 44

29 Fig. 23: Adult patient with hyperparathyroidism. Whole body 99m-Tc scintigraphy demonstrates a 'superscan' with uniformly increased activity throughout the skeleton. Page 29 of 44

30 Fig. 24: Adult patient with hyperparathyroidism (continued from Figure 24). Sestamibi scan of the parathyroid glands demonstrated increased uptake projected over the left lobe of the thyroid gland consistent with parathyroid adenoma (arrow). Page 30 of 44

31 Page 31 of 44

32 Fig. 25: 51 year old female with metastatic breast cancer. Whole body 99m-Tc scintigraphy in this patient with breast cancer demonstrates a 'superscan' with nonuniform increased activity throughout the skeleton secondary to widespread bony metastases. Page 32 of 44

33 Page 33 of 44

34 Fig. 26: 50 year old female with horseshoe kidney. The orientation of the kidney on this whole-body scintigram is typical of that found with a horseshoe kidney with the lower poles pointing medially (arrow). Page 34 of 44

35 Page 35 of 44

36 Fig. 27: 50 year old female with horseshoe kidney (continued from Figure 26). Subsequent T2-weighted axial MRI of the lumbar spine confirmed the presence of a horseshoe kidney. Page 36 of 44

37 Page 37 of 44

38 Fig. 28: 39 year old female with bladder extrophy, pubic diastasis and ureterosigmoidostomy. Excretion of tracer via the ureterosigmoidostomy is noted in this patient with a history of bladder extrophy (arrow). Page 38 of 44

39 Page 39 of 44

40 Fig. 29: 90 year old male with previous myocardial infarction. Whole-body bone scintigraphy with increased uptake of tracer within the left ventricle (arrows). The patient had a history of previous myocardial infarction. Fig. 30: 74 year old male with background history of breast cancer. Posterior bone scintigram demonstrates increased uptake in the ischial tuberosities bilaterally, greater on the left than the right (arrows). Page 40 of 44

41 Fig. 31: 74 year old male with background history of breast cancer (continued from Figure 30). Coronal STIR (left) and T1-weighted (right) sequences from an MRI pelvis demonstrate a chronic avulsion of the right hamstring tendon with avulsion of a bony fragment and high signal within the left hamstring tendon consistent with tendinopathy (arrows). Page 41 of 44

42 Fig. 32: 72 year old female with metastatic breast cancer and portacath device in situ. Anterior bone scintigram demonstrates artefactual tracer uptake in relation to the rightsided portacath (arrows). The patient also has metastatic disease involving the sternum. Page 42 of 44

43 Fig. 33: 41 year old female with newly-diagnosed breast cancer. Whole-body bone scintigraphy demonstrates residual tracer in the left breast from a sentinel node procedure performed 1 day prior to the bone scan. Page 43 of 44

44 Conclusion Radiologists should be familiar with the frequently-encountered pathological but non-malignant processes that commonly result in a positive bone scan, mimicking metastatic disease. The appropriate recommendation of further evaluation with another imaging modality will usually allow accurate characterisation of these lesions, avoiding the requirement for biopsy. Personal Information References Love C, Din AS, Tomas MB, Kalapparambath TP, Palestro CJ. Radionuclide bone imaging: an illustrative review. Radiographics MarApr;23(2): Ziessman HA, O'Malley JP, Thrall JH. Nuclear medicine: the requisites, 3rd d. St Louis, Mo: Mosby, Kim DW, Kim SC, Krynyckyi BR, Machac J, Kim CK. Focally increased activity in the lateral aspect of the mid cervical spine on bone scintigraphy is almost always benign in nature. Clin Nuc Med Sep; 30(9): Buckley O, O'Keeffe S, Geoghegan T, Lyburn ID, Munk PL, Worsley D, Torreggiani WC. 99m Tc bone scintigraphy superscans: a review. Nucl Med Commun Jul;28(7): Palestro CJ, Torres MA. Radionuclide imaging in orthopedic infections. Semin Nucl Med Oct;27(4): Smith SE, Murphey MD, Motamedi K, Mulligan ME, Resnik CS, Gannon FH. From the archives of the AFIP. Radiologic spectrum of Paget disease of bone and its complications with pathologic correlation. Radiographics Sep-Oct;22(5): Halkar RK, Motawy MM, Hebbar HG, Jahan MS. Vertebral body hemangioma showing increased uptake of Tc-99m MDP and decreased Tc-99m labeled red blood cells. Clin Nucl Med Sep;19(9): Page 44 of 44