Effects of transducer position on backscattered intensity in coronary arteries.

Acute myocardial infarction is a frequent cause of sudden death, and is typically initiated by the rupture of coronary artery plaques. The likelihood and severity of rupture are influenced by the plaque structures and components. Radiofrequency (RF) intravascular ultrasound (US) (IVUS-RF) measurements extend current IVUS imaging techniques and may eventually enable the in vivo identification of these features. However, IVUS-RF measurements are affected by the transducer's instantaneous position in the vessel. Specifically, backscattered intensity (BI) decreases as either the distance between the tissue and the transducer increases, or as the beam's angle of incidence on the tissue increases. IVUS-RF data were acquired from seven disease-free coronary arteries in vitro. The 0-dB level for BI was defined as the peak intensity of the reflection from a stainless-steel flat reflector at each distance. The baseline BI measured in adventitial tissue was -32.5 dB (at 0 degrees, 0 mm) with angle and distance dependencies of -0.172 dB/ degrees and -3.37 dB/mm. In contrast, the BI from combined intima and media was -38.2 dB with dependencies of -0.111 dB/ degrees and -4.46 dB/mm (p < 0.05 for all three parameters). Acknowledging and compensating for these effects may allow IVUS-RF to develop into a rapidly deployable tool for the clinical detection of vulnerable plaques and to monitor coronary artery disease progression and regression.

Decongestive lymphatic therapy for patients with breast carcinoma-associated lymphedema. A randomized, prospective study of a role for adjunctive intermittent pneumatic compression.

BACKGROUND: Disruption of the lymphatic circulation through breast carcinoma-associated axillary lymph node dissection, with or without radiation therapy, reportedly is the most common cause of lymphedema in developed countries. There is no cure for breast carcinoma-associated lymphedema. Although intermittent pneumatic compression (IPC) has been acknowledged as a potential component of the multidisciplinary therapeutic strategy in the treatment of patients with breast carcinoma-associated lymphedema, prospective study of its adjunctive safety and efficacy is required. METHODS: IPC was assessed as a component of the initial therapeutic regimen for newly treated patients with breast carcinoma-associated lymphedema. Twenty-three patients who had not previously been treated for lymphedema were randomized to receive either decongestive lymphatic therapy (DLT) alone or DLT with daily adjunctive IPC. Patients with stable, treated, breast carcinoma-associated lymphedema also were assessed in the maintenance phase of therapy. Twenty-seven patients were randomized either to DLT alone or to DLT coupled with daily IPC. In both studies, objective assessment included serial measurement of volume by water displacement, tissue tonometry to assess elasticity of the skin, and goniometry to measure joint mobility. RESULTS: During initial treatment, the addition of IPC to standard DLT yielded an additional mean volume reduction (45.3% vs. 26%; P < 0.05). During maintenance DLT alone, there was a mean increase in volume (32.7 +/- 115.2 mL); with DLT and IPC, there was a mean volume reduction (89.5 +/- 195.5 mL; P < 0.05). In both studies, IPC was tolerated well without detectable adverse effects on skin elasticity or joint range of motion. CONCLUSIONS: When IPC is used adjunctively with other, established elements of DLT, it provides an enhancement of the therapeutic response. IPC is well tolerated and remarkably free of complications.