Pulmonary lymphangitic spread of carcinoma: appearance on CT scans

Chest computed tomography (CT), including high-resolution CT with thin (1.5-mm) sections was used to evaluate proved (pathologically or clinically) lymphangitic spread (LS) of tumor in 12 patients. These appearances were compared with thin-section scans obtained in 11 healthy subjects. Thin-section CT demonstrated findings consistent with thickening of the normal lung interstitium. In all patients, thin sections showed an increase in the number of peripheral lines (1-2 cm in length) that were diffuse in generalized disease and localized in focal disease. Normal peripheral arcades were not increased in number, but the limbs forming the arcades were thickened in all patients. A diffuse increase in linear and curvilinear structures (reticular pattern) was seen toward the center of the lung. Polygonal structures 1-2 cm in diameter were seen in seven patients with LS but not in healthy subjects. Fissures were thickened in nine patients. Selected 1.5-mm-thick CT sections are recommended through abnormal areas (seen at CT or on chest radiographs) or if these are normal at three levels (midapex, hilus, and 3 cm above the diaphragm) when scanning patients with tumors known to cause LS.     

The double puncture: an effective percutaneous technique for removing complex, multiple renal calculi

Percutaneous nephrostolithotomy, which can require a double puncture, is presently the method of choice in our institution for the removal of renal stones. Patients that underwent this procedure were evaluated to identify the possible reasons for the double puncture. Of 200 patients evaluated, 14 needed a second tract. The three variables that determined whether a second puncture was needed, in order of importance, were number and size of the stones, with second tracts needed in patients with multiple stones and staghorn calculi; anatomical variations of the renal collecting system itself, with bifid systems the most significant anatomic variation; and the dexterity of the radiologist in performing the puncture and the ability of the urologist to extract the stone. Second tracts were needed more frequently in patients who presented with stones in both the lower and middle poles of the collecting systems.     

Experience with the Amplatz retrievable vena caval filter. Work in progress

The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.     

Comparison of PET with radioactive microspheres to assess pulmonary blood flow.

Microsphere technique is the reference for assessment of pulmonary blood flow (PBF) but is destructive; PET, however, can determine PBF noninvasively. Comparisons of these 2 methods are scanty. Our study aimed at comparing these 2 techniques using a mathematic model taking into account the right ventricle in determining the transit time of a tracer through lung tissue. METHODS: Ten normal pigs were investigated at baseline, during dobutamine infusion, and during 10 cm H(2)O of positive end-expiratory pressure. Under each condition, PBF was successively measured with PET (PET-PBF) and radioactive microspheres (MS-PBF). For PET-PBF, 2 mCi (74 MBq) (15)O-labeled water were injected intravenously over 20 s and PET scanning was performed for 10 min. The input function was determined noninvasively from PET and invasively from mixed venous blood withdrawals. PET-PBF was computed using a mathematic model taking into account the right ventricle in determining the transit time of the tracer through lung tissue. For MS-PBF, 1 given isotope was injected under a given condition. PET-PBF and MS-PBF for 5 lung regions were compared. RESULTS: PET-PBF significantly correlated with MS-PBF both over all experimental points (PET-PBF = 0.79. MS-PBF + 1,538; r = 0.79; P < 0.001) and in separate lung regions. Invasive and noninvasive input functions also correlated significantly (r = 0.90; P < 0.001). Simulations stressed the crucial role of the right ventricle to the transit time of tracer through lung tissue in the determination of PET-PBF. CONCLUSION: PBF can accurately be assessed using PET and a mathematic model taking into account the right ventricle in determining the transit time of a tracer through lung tissue. Noninvasive determination of the input function of the right ventricle is accurate and can readily be used for clinical applications.     

Hearing-damage risk and communication interference in dental practice

The use of high-speed air-turbine handpieces, operated at 300,000 to 400,000 revolutions per minute, has led to concern over the possibility of noise-induced hearing loss. Sound levels were measured in clinical settings and in a pre-clinical laboratory for estimation of hearing-damage risk among dentists, and the extent of communication interference. Octave-band sound pressure levels were obtained with use of a Fast-Fourier-Transform analyzer and associated instrumentation. The results of this study indicate that the sound energy contribution of a typical dental practice is about 8% to 12% of the dentist's average 24-hour noise exposure. However, noise levels during dental procedures result in an articulation index of 0.21 to 0.37, corresponding to understanding of about 18% to 48% of nonsense syllables and 52% to 90% of sentences. It appears that hearing-damage risk is slight among dentists using modern equipment. However, further noise control in handpieces is necessary so that error-free communication during dental procedures can be ensured.     

Estimates of primary implant power using an intraocular lens table

Intraocular lens (IOL) power data have been compiled in tabular format as a function of axial length measurements, corneal powers, and desired refractive errors. The table is presented to assist the clinician in performing IOL power estimates and as an independent source for checking preoperative IOL power calculations. Ophthalmologists who do not own a personal computer will find the lens power table a valuable adjunct to their present repertoire of analytical skills.     

Effect of varying drop size on the efficacy and safety of a topical beta blocker

We studied the effects on efficacy and safety of varying the drop size of a topical solution of levobunolol 0.5%. In a double-masked, crossover acute study, we administered a single drop of either 35 microL of vehicle, or 20, 35, or 50 microL of levobunolol one hour before the subjects began a ten-minute treadmill challenge electrocardiogram. After exercise the mean heart rate was 111 beats per minute (bpm) in the vehicle group and 102 to 103 bpm in the three levobunolol groups, which were significantly different from the control group but not from each other. In a randomized double-masked, parallel, chronic study, 117 patients with elevated intraocular pressure (IOP) instilled one of the three drop sizes of levobunolol twice daily for three months. Mean decreases in IOP ranged from 5.1 to 6.0 mmHg in the three groups, not significantly different from each other in mean IOP, heart rate, or blood pressure. We conclude that drop size in the range tested had no clinically significant effect on either efficacy or safety of a beta blocker such as levobunolol.