
<b>Of 277 soft tissue sarcoma [STS] patients, approximately 10% had metastases within an average period of 18.6 months from diagnosis.. The regional bones close to the primary tumour were affected in 46% of the patients with bony mets, and the axial bones in 64%.  STS metastatic bony lesions showed predominantly lytic changes, and approximately half of the lesions progressed to pathological fractures. [6]</b>
&&url  PMID: 9250736

<b>Metastases of the Bones Can be Detected:

By Symptoms:</b>  pain or fracture or neurologic deficit.

<b>By Blood Tests:</b>  elevated alkaline phosphatase, elevated bone isoenzyme of alkaline phosphatase, hypercalcemia [blood calcium levels too high].  Current research is aimed at trying to find good blood test markers that indicate bone resorption, and to differentiate metabolic from tumoral problems if possible.   Hopefully techniques would be developed that would allow evaluation of bone tumor response to treatment by a simple blood test.

<b>By Imaging Techniques:</b>
The main imaging techniques used to diagnose bone tumors are conventional Xrays, CT, MRI, and isotope bone scans. Angiography is rarely used, but is helpful when a preoperative selective embolization is needed, or when complex vertebral surgery or vascular surgery is planned.  <b>MRI is the most definitive scan, and is usually done preoperatively. </b>

<b>By Xrays: </b> lytic lesions, usually, 'holes' in bones.  For a lytic lesion to show on Xray, 50% of the bone matrix must be destroyed.  Xrays will not show early stage disease.  Conventional radiography [ regular Xrays] is the screening examination of choice and is sufficient in several benign lesions not requiring treatment. Supplementary imaging studies are usually needed when radiographic findings are questionable and/or the lesion requires treatment. 

<b>By Bone Isotope Scan:</b> will show areas of increased bone activity-including inflammation, arthritis, and infection. It can be thus useful to depict lesion quiescence or activity and to stage any tumor that can metastasize to the skeleton. Bone scan is also helpful to show bone lesions when they are not visible on plain radiographs and can indicate the tumor response to preoperative chemotherapy. 

<b>By MRI scan:</b>  MRI is the scan of choice for depicting any bone tumor.  MRI beautifully shows the different tissues and compartments and it is particularly sensitive in depicting fat. Moreover, it can be repeated many times, even in pregnant women, because it needs no ionizing radiations and iodinated contrast injection; it is also free of artifacts in the patients with orthopedic devices that are usually nonferromagnetic [not responding to magnets like iron does]. However, the execution of an adequate MRI requires experience and knowledge of bone pathologic conditions. 

While Bone Isotope Scans and PET scans are useful adjuncts to indicate strong suspicious of metastases to bone, it is the MRI which is the definitive examination to give clear delineation of the bone tumor and its extent.  No imaging method is without its difficulties, however, and sometimes the MRI cannot distinguish between different types of lesions; one notable situation is between a hemangioma [a noncancerous tumor of twisted blood vessels] and some neoplasms [often also highly vascular].  [Repeatedly on the LMS ACOR List, the MRI has shown the bone mets, despite negative Xrays and negative CT scans.  The scan of choice for the most accurate imaging of bone tumors is MRI.  Ed.]

<b>By PET scan: </b> will show areas of increased metabolic rate, in bone and other organs, including inflammation, arthritis, and infection.  It is a new technique, and its specificity and reliability are still open to interpretation.  

<b>By CT scan:</b> CT best shows mineralized tissues and pulmonary metastases. It is also frequently used as a guide for needle biopsies. Not a good choice for bone studies. 



References: 
1. Campanacci M, Mercuri M, Gasbarrini A, Campanacci L. The value of imaging in the diagnosis and treatment of bone tumors Eur J Radiol 1998 May;27 Suppl 1:S116-22  
2. Krappel FA, Bauer E, Harland U. Efficacy of MRI--whole spine image in diagnosis of vertebral metastases--results of a prospective study. Z Orthop Ihre Grenzgeb 2001 Jan-Feb;139(1):19-25 
3. Woitge HW, Pecherstorfer M,  et.al.   Novel serum markers of bone resorption: clinical assessment and comparison with established urinary indices. J Bone Miner Res 1999 May;14(5):792-801
4. Griffith JF, Kumta SM.  Clinics in diagnostic imaging (25). Aggressive vertebral haemangioma. Singapore Med J 1997 May;38(5):226-30 
5. Savelli G, Maffioli L, Maccauro M, De Deckere E, Bombardieri E., Bone scintigraphy and the added value of SPECT (single photon emission tomography) in detecting skeletal lesions. Q J Nucl Med 2001 Mar;45(1):27-37
6. Yoshikawa H, Ueda T, Mori S, Araki N, Kuratsu S, Uchida A, Ochi T. Skeletal metastases from soft-tissue sarcomas. Incidence, patterns, and radiological features. J Bone Joint Surg Br 1997 Jul;79(4):548-52  PMID: 9250736 
