Forward-looking intravascular ultrasonography: in vitro imaging of normal and atherosclerotic human arteries.

Inadequate guidance of angioplasty devices limits the endoluminal treatment of high grade atherosclerotic stenoses and total occlusions. Conventional intraluminal ultrasound systems (IVUS) enable lateral cross-sectional imaging of tomographic sections of the vessel wall, but do not offer imaging in front of the catheter. This study describes our initial experience with a forward-looking intravascular ultrasound (FL-IVUS) system (Echoeye, EchoCath, Inc., Princeton, NJ). The acoustic beam from a 25.5 MHz piezoelectric transducer on a 7.5 Fr catheter is mechanically rotated in a forward-looking spiral fashion at 300 cycles/second. Sixty-four axially aligned, cross-sectional, real time images are obtained from a truncated, 60 degree conical volume located 5 to 10 mm from the catheter tip. Luminal dimensions (n = 51) of human cadaveric femoral arteries (cast in agar and submerged in saline) measured by the FL-IVUS were compared to histologic cross-sections of the vessel with a correlation of r = 0.92. FL-IVUS accurately imaged the narrowing lumen in front of total occlusions and the geometry at vessel branches, and identified the location of lesions and the shape and morphology of vessel wall thickness. The 7.5 Fr FL-IVUS over-estimated luminal dimensions in vessels larger than 5 mm. We conclude that FL-IVUS imaging shows promise as a new, accurate method for identifying and characterizing high grade atherosclerotic stenoses and total occlusions, and expands the current capabilities of conventional IVUS systems.

Chondrosarcoma of the aorta: a rare source of bowel and lower extremity emboli.

Malignant aortic tumors occur infrequently. At least 70 cases of primary aortic malignancies have been reported in the literature. Within this group, chondrosarcoma is exceedingly rare, with only 1 case having been reported. An aortic chondrosarcoma developed in our patient and embolized to the small bowel and lower extremities. Although initially thought to arise from the abdominal aorta, this tumor, in fact, originated from the thoracic aorta. This case illustrates the need for complete aortic imaging when unexplained recurrent embolization occurs. In general, the survival rates with chondrosarcoma are diminished, but this patient survived 69 months after he was initially seen.