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Objective To assess the capability of monochromatic energy images of Gemstone spectral imaging(GSI) in reducing artifacts caused by metallic implants. Methods Twelve subjects with metallic implants underwent GSI (Discovery CT750 HD, GE Healthcare, Milwaukee ). The metallic orthopedic implants included 3 patients of dentures, 2 patients of cervical spinal vertebraplasty, one clavicle fracture fixation, one lumbar spinal vertehraplasty, 3 patients of artificial femoral head, one iliac fracture fixation and one tibial fracture fixation. GSI was performed by using a single source ultra-fast dual energy X-ray switching (80 kVp and 140 kVp). Following GSI scanning, thin slice images were reconstructed into 1.25 mm slice thickness. The monochromatic energy images were set to the same window width and level (window width 1500 HU,window level 500 HU). The artifact indexes (AI) at different kiloelectronvolts (keV) images were measured and compared. 3D reconstruction was performed using images with minimal AI. Result The artifacts index on monochromatic energy images varied with the change of keV. Of the images from 12 subjects, the maximal AI ranged between 145-225 at 40 keV, and minimal AI ranged between 15-90 at the 95-140 keV. The artifacts are clearly visible on polychromatic energy images and the artifacts are reduced markedly on the monochromatic energy images with minimal AI. Conclusion The artifacts caused by metallic implants can be reduced significantly by GSI with high keV monochromatic energy images.
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Purpose: To describe the clinical manifestations of hepatic myelopathy (HM) after transjugular intrahepatic portosystemic stent shunts (TIPSS)in five patients. Materials and Methods: Four men and one woman, age ranging from 41 to 54 years, had history of hepatitis B and recurrent bleeding from gastroesophageal varices. Obvious liver atrophy was found in the five patients before TIPSS procedure and shunt patency was by color Doppler US after TIPSS. Spinal cord MRI was performed in 4, CT and myelography were performed in lcase. Lumbar puncture was done in 5 patients. Results: Spastic paralysis in the lower extremities occurred progressively during 4 weeks to 4 months after TIPSS in the five patients. Weakness of the upper extremities presented in one patient, and urinary incontinence was in another one. HE following TIPSS occurred more than once (1~6 times) in these patients. Physical ex- amination revealed that hyperreflexia of tendons and positive reaction of ankle clonus were seen in all patients. Superficial sensation was normal in 5, decreasing in deep sesation in 1. Muscular atrophy in the paralytic lower extremities was not obvious in all but one patient. No mass effect or other abnormalities were found in the suspected spinal cords on the imaging studies. Lumbar puncture and cerebrospinal fluid examination were normal. The abnormalities of laboratory tests included hyperammonemia and hypoal- buminemia. Conclusion: Spastic paralysis with intact of superficial sensation in the lower extremity fol- lowing TIPSS should be considered as HM. The potential risk factors of TIPSS related HM were obvious liver atrophy, refractory hyperammonemia and HE follwing TIPSS.