Abstract
Prostate cancer is the most commonly diagnosed non-skin cancer in men. Skeletal metastases are common in prostate cancer; they decrease quality of life, increase the cost of treatment and are a major cause of death and disability. Therefore, it is critically important to accurately detect bone metastasis in order to select appropriate patient management. SPECT-CT provides non-invasive insights into tumour biology and diversity on a whole-body scale as it combines functional information on the biologically active volume of the cancer with structural information locating functional and metabolic signals in relation to the patient anatomy.
Patient History
A 82-year-old man presented 3 years back with signs and symptoms of enlarged prostate and was eventually diagnosed as prostate cancer by Ultrasonography (US), Computed Tomography (CT), and lab tests. The patient was then referred to the Nuclear Medicine department for 99m Tc-MDP scintigraphy to exclude bone metastases. A suspicious vertebral lesion was noticed in the bone scan which was clarified by SPECT-CT imaging.
Findings
Discussion
This study manifests the importance of hybrid machines in situations where the study is equivocal or suspicious. The importance lies in selecting the line of treatment that should be followed by the physician, and this depends on the disease phase and classification. Our patient was a known case of prostatic carcinoma with enlarged prostate and high PSA. He has been followed up for many years back, and several conventional bone scan studies (using our old gamma camera) were done for him, and all were normal. This time we used our newly applied SPECT-CT machine. Initially, the whole body bone scan image showed a suspicious focal radiotracer uptake in the vertebral body of one of the lower lumbar vertebrae. And because there was no other lesion in the axial or appendicular skeleton (except the degenerative knee uptake), there was essential demand to confirm/exclude the diagnosis of metastases since the line of treatment is totally affected by that. The SPECT-CT study, when added, gave the answer to that question, as it provided structural information that located the suspicious focal radiotracer uptake to L4 bony outgrowth diagnosed as an osteophyte. Images were interpreted by a radiologist and a nuclear medicine physician and both readers agreed to exclude a metastatic deposit. That was a happy ending for both patient and doctor, but in addition to that, there was a lesson benefited from this experience. A solitary lesion in bone scan must not be depended on for disease classification, unless confirmed by other modality e.g. biopsy, and hybrid imaging should always be taken into consideration.
In summary, we report a case of prostatic cancer with a solitary suspicious lesion on bone scan in which hybrid SPECT-CT imaging was a problem solving tool as it clarified its origin as degenerative process rather than skeletal metastases.
Conclusion
Hybrid SPECT-CT imaging is very important to clarify diagnostic issues in bone scan when in doubt, especially for solitary lesions. It can also aid in disease classification.
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