Osteoporosis: assessment by quantitative computed tomography

The results presented in this article indicate that quantitative computed tomography provides a reliable means of evaluating and monitoring the many forms of osteoporosis and its various treatments. The greatest advantages of spinal QCT for noninvasive bone mineral measurement are its high precision, the high sensitivity of the vertebral spongiosa measurement site, and the potential for widespread application.     

Effect of percutaneous nephrolithotripsy on renal function: assessment with quantitative SPECT of (99m)Tc-DMSA renal scintigraphy

PURPOSE: To measure the effect of PCNL on global and regional renal function using quantitative single-photon emission CT (SPECT) measurement of Tc-dimercaptosuccinic acid (DMSA) uptake by the kidneys (QDMSA). PATIENTS AND METHODS: A series of 47 male and 41 female patients with a mean age of 47 +/- 16 years were studied by sequential QDMSA examinations before and 1.5 to 24 months after PCNL. Among the 67 patients (76%) in whom PCNL was performed using upper- or lower-pole access, the function of the affected and nonaffected poles of the treated kidney was calculated separately. RESULTS: There was no statistically significant difference in the uptake by the treated kidneys before versus after PCNL (11.9% +/- 5% v 11.6% +/- 5%; t = 0.9; P = 0.368). The total functional volume of the treated kidney was slightly decreased, from 235 cc +/- 62 cc to 224 cc +/- 59 cc (t = 2.7; P = 0.011). The percent of the injected isotope dose per cubic centimeter of tissue of the treated kidney was not affected (0.051 +/- 0.02 v 0.053 +/- 0.02; t = 0.86; P = 0.296). Regional assessment revealed a statistically significant decrease in the functional volume at the PCNL port of entry (91 cc +/- 30 cc v 82 cc +/- 27 cc; t = 2.64; P = 0.013). Regarding the percent of the injected dose per cubic centimeter of renal tissue, no statistically significant difference was found between the area of the kidney that underwent PCNL and the untreated area of the same kidney (0.049 +/- 0.02 v 0.05 +/- 0.02; t = 0.693; P = 0.494). The function of the contralateral kidneys remained unchanged (13.4% +/- 5.2% v 13.6% +/- 4.8%; t = 0.68; P = 0.5). CONCLUSIONS: Despite the statistically significant decrease in the functional volume of the surgically treated region, neither total percent uptake nor percent of injected dose were reduced significantly. Further studies with long-term follow-up of treated kidneys are required.     

Madelung's deformity: quantitative assessment of x-ray deformity

PURPOSE: To evaluate 5 defined measurement techniques that are applicable to x-rays of Madelung's deformity: ulnar tilt, lunate subsidence, lunate fossa angle, palmar tilt, and palmar carpal displacement. The measurements rely on the longitudinal axis of the ulna and the carpal bones to determine drawing lines and avoid the distorted distal radius and its deformed lunate fossa. The reliability and reproducibility of the measurements is determined. METHODS: Forty-eight sets of posteroanterior and lateral x-ray views of the wrist of subjects with the clinical diagnosis of Madelung's deformity were measured by 4 raters. Each rater made the 5 defined measurements on each pair of x-rays. Pairs of raters were compared for reliability using the Pearson correlation coefficient and Lin's concordance correlation coefficient. Two raters repeated the 4 reliable measurements a minimum of 6 months after the first measurements. Each rater's results were compared for reproducibility using Lin's concordance correlation coefficient. RESULTS: Ulnar tilt and lunate subsidence have excellent reliability and reproducibility. Palmar carpal displacement has acceptable reliability and reproducibility. Lunate fossa angle has borderline reliability but excellent reproducibility. Palmar tilt has poor reliability. CONCLUSIONS: Ulnar tilt, lunate subsidence, and palmar carpal displacement, as defined, are considered reliable and reproducible measurements for quantifying the severity of Madelung's deformity on x-rays. Lunate fossa angle is not sufficiently reliable for comparing preoperative and postoperative wrists but may prove useful in establishing an early diagnosis. Palmar tilt is not measured reliably on a lateral x-ray because of the superimposition of multiple structures on a lateral x-ray and the absence of the volar part of the lunate fossa in patients with severe Madelung's deformity. Advanced imaging techniques are needed to delineate the deformity of the distal radius in a lateral projection.     

影像学定量分析二尖瓣研究进展

二尖瓣反流是一种常见的心脏瓣膜疾病。二尖瓣的三维立体结构复杂,各组成部分协调工作,使血液顺利从左心房泵入左心室。全面、准确定量评估二尖瓣结构有利于制定最佳治疗方案,选择手术时机及评估预后。本文对影像学定量测量二尖瓣研究进展进行综述。     

Cimetidine therapy for burn shock: a quantitative assessment

Optimal cardiac output (CO) resuscitation for severely burned guinea pigs is obtained with intravenous volumes of lactated Ringer's (LR) calculated at 4 cc/kg/%burn/24 hr. When one half this volume of LR is given (2 cc/kg/%burn/24 hr) CO is significantly (p less than 0.05) reduced at 2, 4, and 8 hours after injury. When early postburn cimetidine therapy (0.5 hours after injury) is added to only 1 cc/kg/%burn/24 hr LR, CO is significantly elevated for the same time periods and is not significantly different from CO values of LR at 4 cc/kg/%burn/24 hr for the first 24 hours after injury. However, postburn cimetidine therapy delayed until 1 hour after burn injury did not improve CO compared to treatment with LR at 2 cc/kg/%burn/24 hr. These observations suggest that early postburn cimetidine therapy administered within 1/2-hour of severe scald injury will result in significant CO improvement while simultaneously reducing resuscitative fluid volume requirements by as much as 70% for the first 24 hours after injury.     

Ultrasound assessment of residual urine. A quantitative method

A method of measuring residual urine volume using ultrasound is described. The volume is computed from serial parallel sections of the bladder. This method is found to be significantly more accurate than previously reported techniques and is quick and easy to perform.     

Normal postural stability and steadiness: quantitative assessment.

A force platform was utilized to provide a new and sensitive means to measure postural steadiness and stability. Normal standards are presented for the center of pressure of the vertical supportive force during standing and sustained weight-shifting of normal men in three age groups. Two distinguishing characteristics were seen for normal upright posture: (1) a large area of stability over which weight can be safely shifted and maintained, and (2) steadiness such that the center of pressure fluctuates incessantly, traversing large total excursions, while remaining remarkably close to the mean point. The youngest age group showed the greatest steadiness and stability and the oldest group showed the least.     

Multiparameter quantitative computer-assisted tomography assessment of unicompartmental knee arthroplasties

BACKGROUND: Unicompartmental knee arthroplasty is a popular alternative to total knee replacement in selected patients. Component alignment has not yet been described by computer-assisted tomography (CAT) imaging techniques; these have been developed for total knee arthroplasty analysis. The aims of this study were to report two new technologies; a new unicompartmental knee arthroplasty system was radiographically assessed with a new CAT scan protocol. METHODS: In a consecutive cohort study, 60 knees were analysed by the 'UniCAT Protocol'. Patients were implanted with a unicompartmental knee arthroplasty system that uses a unique ligament tensor for femoral component alignment. The uniCAT protocol requires a long anteroposterior and lateral scout scan to measure limb alignment and component orientation. A spiral computer-assisted tomography at the knee is used to measure component rotation. The total scan time was 20 s with a calculated unshielded radiation dose of 1 mSv or less. RESULTS: The mechanical axis had a mean of 2.7 degrees varus. Femoral components were implanted with a mean of 0.37 degrees valgus and 1.3 degrees flexion. Tibial components were implanted with a mean 3.47 degrees varus and 5.1 degrees posterior slope. Femoral components were externally rotated a mean of 3.36 degrees, tibial components were externally rotated 6.59 degrees from the posterior tibia and 5.68 degrees from the transepicondylar axis. CONCLUSION: The UniCAT protocol uses less radiation than whole-limb spiral scans and is a method that can be used with all modern computer-assisted tomography machines. The coronal and sagital alignment results compare favourably with previous published reports without computer-assisted tomography. Component rotation has not previously been reported and its implications are yet to be defined.     

Computer-assisted total knee replacement. A controlled cadaver study using a multi-parameter quantitative CT assessment of alignment (the Perth CT Protocol)

A controlled study, comparing computer- and conventional jig-assisted total knee replacement in six cadavers is presented. In order to provide a quantitative assessment of the alignment of the replacements, a CT-based technique which measures seven parameters of alignment has been devised and used. In this a multi-slice CT machine scanned in 2.5 mm slices from the acetabular roof to the dome of the talus with the subject's legs held in a standard position. The mechanical and anatomical axes were identified, from three-dimensional landmarks, in both anteroposterior and lateral planes. The coronal and sagittal alignment of the prosthesis was then measured against the axes. The rotation of the femoral component was measured relative to the transepicondylar axis. The rotation of the tibial component was measured with reference to the posterior tibial condyles and the tibial tuberosity. Coupled femorotibial rotational alignment was assessed by superimposition of the femoral and tibial axial images. The radiation dose was 2.7 mSV. The computer-assisted total knee replacements showed better alignment in rotation and flexion of the femoral component, the posterior slope of the tibial component and in the matching of the femoral and tibial components in rotation. Differences were statistically significant and of a magnitude that support extension of computer assistance to the clinical situation.