Imaging-guided radiofrequency ablation of solid renal tumors.

OBJECTIVE: We performed a retrospective review of imaging-guided radiofrequency ablation of solid renal tumors. MATERIALS AND METHODS: Since May 2000, 35 tumors in 20 patients have been treated with radiofrequency ablation. The size range of treated tumors was 0.9-3.6 cm (mean, 1.7 cm). Reasons for patient referrals were a prior partial or total nephrectomy (nine patients), a comorbidity excluding nephrectomy or partial nephrectomy (10 patients), or a treatment alterative to nephron-sparing surgery (one patient who refused surgery). Tumors were classified as exophytic, intraparenchymal, or central. Sixteen patients had 31 lesions that showed serial growth on CT or MR imaging. Of these 16 patients, four patients with 10 lesions had a history of renal cell carcinoma, and two patients with 11 lesions had a history of von Hippel-Lindau disease. Four patients had incidental solid masses, two of which were biopsied and shown to represent renal cell carcinoma, and the remaining two masses were presumed malignant on the basis of imaging features. Successful ablation was regarded as any lesion showing less than 10 H of contrast enhancement on CT or no qualitative evidence of enhancement after IV gadolinium contrast-enhanced MR imaging. RESULTS: Of the 35 tumors, 22 were exophytic and 13 were intraparenchymal. Twenty-seven of the 35 were treated percutaneously using either sonography (n = 22) or CT (n = 5). Two patients had eight tumors treated intraoperatively using sonography. Patients were followed up with contrast-enhanced CT (n = 18), MR imaging (n = 5), or both (n = 5) with a follow-up range of 1-23 months (mean, 9 months). No residual or recurrent tumor and no major side effects were seen. CONCLUSION: Preliminary results with radiofrequency ablation of exophytic and intraparenchymal renal tumors are promising. Radiofrequency ablation is not associated with significant side effects. Further follow-up is necessary to determine the long-term efficacy of radiofrequency ablation.

Ultrasound grayscale image compression with JPEG and wavelet techniques.

The purpose of the study was to evaluate the effects of lossy compression on grayscale ultrasound images to determine how much compression can be applied while still maintaining images that are acceptable for diagnostic purposes. The study considered how the acquisition technique (video frame-grabber versus directly acquired in digital form) influences how much compression can be applied. For directly acquired digital images, the study considered how text (that is burned into the image) affects the compressibility of the image. The lossy compression techniques that were considered include JPEG and a Wavelet algorithm using set partitioning in hierarchical trees (SPIHT).

Anatomy of the ulnar nerve at the elbow: potential relationship of acute ulnar neuropathy to gender differences.

Men develop perioperative ulnar neuropathies more frequently than women. To determine the role of anatomical gender differences in the development of these neuropathies, we performed several studies of the anatomy of the ulnar nerve, cubital tunnel, and elbow region. These studies included detailed dissection of male and female embalmed and unembalmed cadavers, ultrasound measurements of the tissue layers at the elbow, and measurement of various dimensions of the coronoid process of the ulna in multiple skeletal sets. No gross anatomical differences were found between genders regarding the course of the ulnar nerve through the upper limb. However, there was a strikingly larger (2-19 times greater) fat content on the medial aspect of the elbow in women compared to men, and the tubercle of the coronoid process was approximately 1.5 times larger in men (P < or = .002, rank sum test). Our finding suggest that the tubercle of the coronoid process is a likely area for external compression-induced ischemia of the ulnar nerve because the nerve and its arterial supply (the posterior ulnar recurrent artery) are covered at the tubercle only by skin, subcutaneous fat, and a very thin aponeurosis of the flexor carpi ulnaris. Importantly, this tubercle is larger and the nerve and blood vessels passing by it are less protected by subcutaneous fat in men than in women. These two anatomical differences between men and women may contribute to the increased frequency of perioperative ulnar neuropathy induced by external pressure at the medial aspect of the elbow in men.

Studies of malformation syndromes of man XXXXIA: anatomical studies in the Hanhart syndrome--a pathogenetic hypothesis.

Two infants with the Hanhart syndrome, i.e. micrognathia, microglossia, terminal deficiency of all limbs and imperforate anus in one, were dissected and studied in detail. The interrelationships of the muscular and skeletal defects suggested that they were the result of incomplete rather than abnormal morphogenesis. We speculate that the oral and limb abnormalities resulted from deficient mesodermal proliferation caused by disturbances in the ectodermal-mesodermal interactions beginning about the 4th week of development. The imperforate anus may also relate to the proposed defect.