Central venous catheter mimicking metastasis on a bone scan – advantage of a hybrid imaging

Summary

66-y-old lady was sent to our department for a bone scan as a part of an investigation of a tumor of unknown origin. She cooperated;  she  was  afebrile,  without  dyspnea  or  icterus. She suffered from dysorexia but she did not loss her weight. She  had  a  hypertension; diabetes compensated with oral antidiabetics; and hypothyroidism compensated with a treatment. Her oncological history was negative. Basic physical

examination was normal except obesity. Chest X-ray was negative, abdominal sonography suspected liver cirrhosis with an ascites, proved cholecystolithiasis. Gastroscopy detected hiatal hernia and ulcer on the large curvature with mucosal

infiltration but histology was negative regarding a tumor. Gynaecological work-up including sonography was also negative. Central venous catheter into the right subclavian vein was inserted due to an obesity and a poor venous access.

Whole-body bone scan was performed routinely 3 hours after injection of 800 MBq of ^99mTc-HDP on a gamma camera BrightView XCT (Philips). Radiopharmaceutical was administered into the catheter which was flushed with 20 ml of normal saline before and after injection. Focally increased accumulation in the right sternoclavicular joint and in the dorsal right 5th rib paravertebrally was detected except of physiological accumulation in the bone tissue of an axial skeleton and large joints. (Fig. 1) We performed a SPECT/CT of the thorax for better specification. (Fig. 2) The focally increased accumulation was evident near the end of the catheter; no accumulation  was detected in the sternoclavicular joint or in the right 5th rib; these foci were detected due to shining through to the detectors only. We concluded that the bone scan is physiological without signs of metastases. Renal failure with a mineral breakup progressively occurred and the patient died under the picture or a cardiopulmonary failure 4 weeks after an admission. Primary tumor was not detected, oncological therapy was not provided.

Key words:

bone scan, extraosseous accumulation, catheter, SPECT/CT