Effective cleaning and decontamination of the internal air and water channels, heads and head-gears of multiple contra-angle dental handpieces using an enzymatic detergent and automated washer-disinfection in a dental hospital setting.

BACKGROUND: Dental handpieces (DHPs) are reusable invasive medical devices that must be cleaned, decontaminated, lubricated and steam sterilized after use. DHPs have a complex internal design including narrow channels, contamination of which can compromise sterilization. DHPs are not designed for routine disassembly, making cleaning/decontamination efficacy difficult to monitor. Washer-disinfection is the preferred method of decontaminating DHPs, but few studies have investigated its direct effectiveness at reducing microbial contamination internally. AIMS: To use contra-angle DHPs as a model system to investigate the effectiveness of washer-disinfection at reducing microbial contamination of internal components of multiple DHPs. METHODS: The air and water channels and heads of 10 disassembled contra-angle DHPs (BienAir, Biel/Bienne, Switzerland) were inoculated separately with 108 colony forming units (cfu) of Pseudomanas aeruginosa, Staphylococcus aureus, Enterococcus hirae or Candida albicans in the presence of 0.3% bovine serum albumin (BSA) (clean conditions), 3.0% BSA or 10% artificial test soil (dirty conditions). After reassembly, all 10 DHPs underwent washer-disinfection simultaneously in a Míele (Míele Ireland Ltd., Dublin, Ireland) PG8528 washer-disinfector and were tested for reductions in micro-organisms and protein. Additional experiments were undertaken with three lubricated DHPs inoculated with S. aureus and 10% test soil. All experiments were repeated in triplicate. FINDINGS: On average, an approximate 5 log or greater reduction in microbial cfu and a >93% reduction in protein from DHP heads and channels was consistently recorded following washer-disinfection for all DHPs under all conditions tested. CONCLUSIONS: The internal components of multiple DHPs can be effectively cleaned and decontaminated by washer-disinfection.

Whole-genome sequencing identifies highly related Pseudomonas aeruginosa strains in multiple washbasin U-bends at several locations in one hospital: evidence for trafficking of potential pathogens via wastewater pipes.

BACKGROUND: Hand washbasin U-bends have increasingly been associated with nosocomial outbreaks by Gram-negative bacteria, including Pseudomonas aeruginosa which is virtually ubiquitous in U-bends. Wastewater networks servicing U-bends are potential highways for trafficking pathogenic bacteria. AIM: To use P. aeruginosa to investigate trafficking of bacteria between hospital washbasin U-bends. METHODS: Twenty-five washbasin U-bends in five locations in Dublin Dental University Hospital (DDUH) were investigated for trafficking of P. aeruginosa: 10 in Clinic 2 (C2), 10 in the Accident & Emergency Department (A&E) and five in three other locations. In addition, washbasin tap samples (N=80) and mains and tap water samples (N=72) were cultured for P. aeruginosa. Selected P. aeruginosa isolates recovered over 29 months underwent whole-genome sequencing, and relatedness was interpreted using whole-genome multi-locus sequence typing and pairwise single nucleotide polymorphism (SNP) analysis. FINDINGS: P. aeruginosa was recovered from all U-bends but not from taps or water. Eighty-three U-bend isolates yielded 10 sequence types (STs), with ST560 and ST179 from A&E, C2 and two other locations predominating (70%). ST560 was also recovered from a common downstream pipe. Isolates within ST560 and ST179 were highly related regardless of source. ST560 was divided into Cluster I (N=25) and Cluster II (N=2) with average allelic differences and SNPs of three and zero, and two and five, respectively. The 31 ST179 isolates exhibited an average allelic difference and SNPs of three and 12, respectively. CONCLUSION: Highly related P. aeruginosa strains were identified in multiple U-bends in several DDUH locations, indicating trafficking via the wastewater network.

Minimizing microbial contamination risk simultaneously from multiple hospital washbasins by automated cleaning and disinfection of U-bends with electrochemically activated solutions.

BACKGROUND: Outbreaks of infection associated with microbial biofilm in hospital hand washbasin U-bends are being reported increasingly. In a previous study, the efficacy of a prototype automated U-bend decontamination method was demonstrated for a single non-hospital pattern washbasin. It used two electrochemically activated solutions (ECA) generated from brine: catholyte with detergent properties and anolyte with disinfectant properties. AIM: To develop and test a large-scale automated ECA treatment system to decontaminate 10 hospital pattern washbasin U-bends simultaneously in a busy hospital clinic. METHODS: A programmable system was developed whereby the washbasin drain outlets, U-bends and proximal wastewater pipework automatically underwent 10-min treatments with catholyte followed by anolyte, three times weekly, over five months. Six untreated washbasins served as controls. Quantitative bacterial counts from U-bends were determined on Columbia blood agar, Reasoner's 2A agar and Pseudomonas aeruginosa selective agar following treatment and 24 h later. FINDINGS: The average bacterial densities in colony-forming units/swab from treated U-bends showed a >3 log reduction compared with controls, and reductions were highly significant (P<0.0001) on all media. There was no significant increase in average bacterial counts from treated U-bends 24 h later on all media (P>0.1). P. aeruginosa was the most prevalent organism recovered throughout the study. Internal examination of untreated U-bends using electron microscopy showed dense biofilm extending to the washbasin drain outlet junction, whereas treated U-bends were free from biofilm. CONCLUSION: Simultaneous automated treatment of multiple hospital washbasin U-bends with ECA consistently minimizes microbial contamination and thus the associated risk of infection.

Elimination of biofilm and microbial contamination reservoirs in hospital washbasin U-bends by automated cleaning and disinfection with electrochemically activated solutions.

BACKGROUND: Washbasin U-bends are reservoirs of microbial contamination in healthcare environments. U-Bends are constantly full of water and harbour microbial biofilm. AIM: To develop an effective automated cleaning and disinfection system for U-bends using two solutions generated by electrochemical activation of brine including the disinfectant anolyte (predominantly hypochlorous acid) and catholyte (predominantly sodium hydroxide) with detergent properties. METHODS: Initially three washbasin U-bends were manually filled with catholyte followed by anolyte for 5min each once weekly for five weeks. A programmable system was then developed with one washbasin that automated this process. This U-bend had three cycles of 5min catholyte followed by 5min anolyte treatment per week for three months. Quantitative bacterial counts from treated and control U-bends were determined on blood agar (CBA), R2A, PAS, and PA agars following automated treatment and on CBA and R2A following manual treatment. FINDINGS: The average bacterial density from untreated U-bends throughout the study was >1×10(5) cfu/swab on all media with Pseudomonas aeruginosa accounting for ∼50% of counts. Manual U-bend electrochemically activated (ECA) solution treatment reduced counts significantly (<100cfu/swab) (P<0.01 for CBA; P<0.005 for R2A). Similarly, counts from the automated ECA-treatment U-bend were significantly reduced with average counts for 35 cycles on CBA, R2A, PAS, and PA of 2.1±4.5 (P<0.0001), 13.1±30.1 (P<0.05), 0.7±2.8 (P<0.001), and 0 (P<0.05) cfu/swab, respectively. P. aeruginosa was eliminated from all treated U-bends. CONCLUSION: Automated ECA treatment of washbasin U-bends consistently minimizes microbial contamination.

Balancing urgency, age and quality of life in organ allocation decisions--what would you do? A survey.

PURPOSE: Explore public attitudes towards the trade-offs between justice and medical outcome inherent in organ allocation decisions. BACKGROUND: The US Task Force on Organ Transplantation recommended that considerations of justice, autonomy and medical outcome be part of all organ allocation decisions. Justice in this context may be modeled as a function of three types of need, related to age, clinical urgency, and quality of life. METHODS: A web-based survey was conducted in which respondents were asked to choose between two hypothetical patients who differed in clinical urgency (time to death <1 year), age, pretransplant and post-transplant quality of life, and life expectancy. RESULTS: A pool of 1600 people were notified via email about the survey; 623 (39%) responded. Respondents preferred giving organs to younger people up to an age difference of <15.4 years (SD 18) and more clinically urgent people up to a difference in urgency of <2.54 months (SD 3). Priority varied with the quality of life of the worst-off patient and the relative status of the patients. If both had worse than average quality of life, respondents preferred the better-off patient. When both had better than average quality of life, they preferred the worse-off patient. In analysis according to age versus clinical urgency, the older the patient, the more urgency needed to receive priority. In quality of life versus clinical urgency, the better the control's quality of life, the more urgency the competing patient required. The worse the patient's post-transplant outcome, the more urgency needed to receive priority. CONCLUSIONS: It appears that clinical urgency is only one of many factors influencing attitudes about allocation decisions and that respondents may invoke different principles of fairness depending the relative clinical status of patients.

Rabbit corneal hydration and the bicarbonate pump.

Experiments were conducted on the transport properties of the rabbit corneal endothelium at 22 degrees C, at which temperature the endothelium was able to stabilize the hydration of corneal stroma at physiological values. When bicarbonate was omitted from the bathing solution, the cornea swelled at 11 +/- 1 microm x h(-1). The swelling was completely reversible upon the subsequent re-introduction of bicarbonate. Similar swelling rates were observed when the endothelial pump was irreversibly inhibited with ouabain. In an Ussing-type chamber, the endothelium developed an electrical resistance of 25.0 +/- 1.0 ohms x cm2 and a short circuit current (s.c.c.) of 6.0 +/- 1.1 microA x cm(-2). Neither electrical resistance of the corneal endothelium nor its s.c.c. were changed significantly after exposure to 0.5 mM amiloride. Ouabain abolished the s.c.c. but had no significant effect on resistance. When paired preparations were short-circuited, the endothelium developed a net H[14C]O3- flux of 0.24 +/- 0.03 micromoles x cm(-2) x h(-1) into the aqueous humour, which was close in magnitude and direction to the s.c.c. of 0.22 +/- 0.01 microEq x cm(-2) x h(-1). There was no significant net flux of 86Rb (0.04 +/- 0.03 micromoles x cm(-2) x h(-1)). Similar magnitude fluxes for both bicarbonate and rubidium were found with open-circuit preparations. It is suggested that a metabolically driven electrogenic bicarbonate current passing across the corneal endothelium is solely responsible for maintaining corneal hydration at 22 degrees C. Based on these and other studies, a model is proposed for active bicarbonate transport across corneal endothelium consisting of uphill entry into the cell through a baso-lateral membrane sodium/bicarbonate cotransporter (NBC) and downhill exit through an apical membrane anion channel. Studies on the transport properties of the endothelium at 35 degrees C are discussed and reasons suggested for the discrepancy between short circuit current and net bicarbonate flux at this closed eye temperature.

Effects of eicosapentaenoic acid on cardiac SR Ca(2+)-release and ryanodine receptor function.

n-3 polyunsaturated fatty acids (PUFAs) can prevent life-threatening arrhythmias but the mechanisms responsible have not been established. There is strong evidence that part of the antiarrhythmic action of PUFAs is mediated through inhibition of the Ca(2+)-release mechanism of the sarcoplasmic reticulum (SR). It has also been shown that PUFAs activate protein kinase A (PKA) and produce effects in the cardiac cell similar to beta-adrenergic stimulation. We have investigated whether the inhibitory effect of PUFAs on the Ca(2+)-release mechanism is caused by direct inhibition of the SR Ca(2+)-release channel/ryanodine receptor (RyR) or requires activation of PKA. Experiments in intact cells under voltage-clamp show that the n-3 PUFA eicosapentaenoic acid (EPA) is able to reduce the frequency of spontaneous waves of Ca(2+)-release while increasing SR Ca(2+) content even when PKA activity is inhibited with H-89. This suggests that the EPA-induced inhibition of SR Ca(2+)-release is not dependent on activation of PKA. Consistent with this, single-channel studies demonstrate that EPA (10-100 microM), but not saturated fatty acids, reduce the open probability (Po) of the cardiac RyR incorporated into phospholipid bilayers. EPA also inhibited the binding of [3H]ryanodine to isolated heavy SR. Our results indicate that direct inhibition of RyR channel gating by PUFAs play an important role in the overall antiarrhythmic properties of these compounds.

The effect of injection rate on time-resolved contrast-enhanced peripheral MRA.

In contrast-enhanced (CE) magnetic resonance (MR) angiography (MRA), lower injection rates of a fixed contrast agent dose provide longer contrast agent bolus at the expense of lower intravascular signal. This study evaluated the effect of different injection rates in imaging of the vasculature of the lower extremities with time-resolved, CE MRA. In three volunteers, injection rates of 0.5, 1.5 and 3.0 mL/second were administered in a randomized order and imaged in two separate sessions. Contrast agent bolus dynamics measured in volunteers were used in computer simulations to confirm variations in contrast agent concentration as a source of vessel ringing and blurring artifacts. To validate the effect of injection rate in pathologic vessels, 37 patients with peripheral vascular disease were imaged with a time-resolved technique using an injection rate of 0.5 mL/second or 1.5 mL/second and retrospectively divided into two groups. In volunteers, higher injection rates caused a stronger modulation of k-space and resulted in increased ringing artifacts in time-resolved CE MRA. These results were reproduced with computer simulations. In the qualitative patient study, significantly less vessel blurring was observed using a lower injection-rate, without a significant loss of vessel contrast.

Method for rapidly determining and reconstructing the peak arterial frame from a time-resolved CE-MRA exam.

A method that determines the information necessary to reconstruct a single vascular image from a time-resolved CE-MRA exam is presented. Raw k-space data are used to approximate the time course of the contrast passage prior to image reconstruction. The resulting k-space contrast curve is used to select the data corresponding to peak arterial enhancement. These data are reconstructed and immediately presented for physician review, with the entire time-series of images available at a later time for more detailed diagnosis. This approach dramatically reduces the latency between acquisition of large 4D (3D plus time) data sets and presentation of a diagnostic quality time frame. This algorithm has proven successful in the imaging of several anatomical regions and-in exams that do not require a breath hold-permits the use of an acquisition method that produces a contrast-enhanced angiogram without a timing scan.

Magnetic resonance angiography of aorto-iliac disease.

BACKGROUND: Four different techniques for aorto-iliac magnetic resonance angiography (MRA) were assessed for accuracy using a digital subtraction angiography (DSA) gold standard. Surgeons' confidence in their ability to generate treatment plans with MRA and DSA was assessed, in consultation with a radiologist. METHODS: Two different two-dimensional (2D) time-of-flight (TOF) sequences, a phase-contrast sequence, and a contrast-enhanced (CE) MRA sequence were used. Receiver operating characteristic (ROC) curves were plotted and areas (A(z)) calculated from radiologists' readings. Surgeons' confidence in their ability to utilize the images for treatment planning was assessed with a 5-point Likert scale. Thirty-six patients were evaluated. RESULTS: CE MRA had a sensitivity, specificity, and A(z) of.92,.93, and.96, respectively, for stenoses 50% or greater. CE MRA performed better than other sequences, but the improvement compared with gated 2D TOF was not statistically significant. Interobserver agreement for CE MRA and DSA yielded identical Kappa values. Surgeons were most confident in DSA, followed by CE MRA, which was significantly preferred to other techniques. CONCLUSIONS: CE MRA closely approximates DSA in terms of diagnostic accuracy. Surgeons considering treatment plans are confident in the CE MRA technique, relative to other MRA methods.

3D MR DSA: effects of injection protocol and image masking.

The purpose of this study was to investigate the effect on three-dimensional (3D) magnetic resonance digital subtraction angiography (MR DSA) images of various injection protocol parameters (ie, injection order, volume, and rate), as well as image masking. The pelves of 10 normal volunteers were scanned using seven different contrast agent volume/injection rate combinations. Subtraction of a precontrast mask image resulted in vascular image contrast improvements of between 4.0 and 7.7 times. Image quality and smaller vessel image contrast in the masked data decreased with increasing injection number. Data acquired with a high (0.150 mmol kg(-1)) volume yielded the highest quality images, although only small nonsignificant differences in image quality and large vessel conspicuity were found between images obtained using the high and medium (0.075 mmol kg(-1)) volumes. Images acquired with a low (0. 038 mmol kg(-1)) volume, while of lower image contrast, were judged to be of reasonable quality, especially when acquired as the first or second injection. Injection rate (1 ml s(-1), 2 ml s(-1), and 4 ml s(-1)) was not found to affect the images significantly, although selection of an injection rate that gave an injection duration of approximately 10 seconds tended to give better vascular image contrast. Based on these data, a series of escalating volumes for multi-injection examination is proposed. J. Magn. Reson. Imaging 2000;12:476-487.

A time-tradeoff method for cost-effectiveness models applied to radiology.

PURPOSE: The wait tradeoff (WTO) is a simple time-tradeoff method designed for temporary health states that uses a realistic and intuitive interface for the patient/subject. This method was tested by assessing patients' preferences for magnetic resonance angiography (MRA) versus x-ray angiography (XRA). MATERIALS AND METHODS: The WTO was tested by telephone interview in 38 patients with atherosclerotic peripheral vascular disease, all having previously undergone both MRA and XRA. At indifference point, patients were ambivalent about having MRA or XRA and immediate treatment, versus having a waiting period for test results and treatment after a hypothetical "ideal test" that entailed no pain or risk. RESULTS: The patients were willing to wait a mean of 42.1 days after the ideal test for results and treatment, as opposed to XRA. They were willing to wait only 16.1 days as opposed to MRA. This difference in waiting times was significant (p = 0.0001) and indicates a clear preference for MRA, in agreement with known literature. CONCLUSION: The WTO method assesses preferences for these radiologic tests in an intuitive fashion that does not invoke artificial or irrelevant health states. This approach may also prove useful for other testing situations or short-term treatments being evaluated for cost-effectiveness.

Comparison of treatment plans for lower extremity arterial occlusive disease made with electrocardiography-triggered two-dimensional time-of-flight magnetic resonance angiography and digital subtraction angiography.

BACKGROUND: The purpose of the study was to determine whether preoperative treatment plans for patients with lower extremity ischemia can be made with electrocardiography (EKG)-triggered two-dimensional (2D) time-of-flight (TOF) magnetic resonance angiography (MRA) as accurately as digital subtraction angiography (DSA). METHODS: Forty patients were prospectively evaluated with the combination of EKG-triggered 2D TOF MRA, DSA, and pulse volume recordings. Blinded reviewers graded arterial segments for disease severity. Accuracy of separate MRA- and DSA-based treatment plans was compared with the procedures performed based on all available information. RESULTS: There was an 86% exact match between MRA- and DSA-based plans (92% MRA and 94% DSA accuracy). The MRA-based plan accurately predicted 90% of suprainguinal and 95% of infrainguinal procedures, whereas the DSA-based plan accurately predicted 100% of suprainguinal and 85% of infrainguinal procedures. Two-year primary patency was 83% for all procedures. Radiologists' review of disease severity resulted in a mean exact correlation between studies of 81% (kappa = 0.64). The agreement between radiologists interpreting the MRA was 84% (kappa = 0.7) compared with 82% (kappa = 0.66) for the DSA. CONCLUSIONS: MRA- and DSA-based preoperative management plans were of comparable efficacy. Significant interobserver variability was seen with the interpretations of both preoperative studies. EKG-triggered 2D TOF MRA can be used to plan arterial reconstructions; however, all patients require arterial pressure measurements prior to suprainguinal repair and confirmatory intraoperative angiography during infrainguinal revascularization.

Contrast-enhanced 3D MR DSA of the carotid artery bifurcation: preliminary study of comparison with unenhanced 2D and 3D time-of-flight MR angiography.

PURPOSE: To compare the delineation of stenosis at the carotid artery bifurcation on three-dimensional (3D) magnetic resonance (MR) digital subtraction angiographic (DSA) images with that on two-dimensional (2D) and 3D time-of-flight (TOF) MR angiographic images. MATERIALS AND METHODS: Twenty-six patients with 29 carotid artery bifurcations and symptoms of cerebral ischemia underwent 3D MR DSA. A time-resolved series was generated with 3D MR DSA after the bolus injection of gadodiamide. The resolution for a carotid artery examination was 0.4 x 0.4 x 1.0 mm, with volumes reconstructed at 4.5-second intervals. The 3D MR DSA images were compared with contemporaneously acquired unenhanced 2D and 3D TOF images. Two observers ranked the 2D and 3D TOF MR angiographic and 3D MR DSA images according to the following: (a) stenosis delineation, (b) internal carotid artery delineation, (c) intravascular signal intensity, and (d) diagnostic confidence. RESULTS: The mean ranking for diagnostic confidence was 1.10 (1 = best technique, 3 = worst technique) for 3D MR DSA. Compared with the pooled 2D TOF and 3D TOF ranks, the 3D MR DSA rank was significantly better (P < .01). Similar levels of statistical significance were found for the other criteria. CONCLUSION: Three-dimensional MR DSA improves the delineation of carotid arterial stenosis by virtually eliminating saturation effects and reducing intravoxel dephasing. Surface morphology and nearly occluded vessels ("string sign") were easily identified. Confidence in identifying carotid arterial occlusions was also very high with this technique.

Hashimoto's thyroiditis and insulin-dependent diabetes mellitus: differences among individuals with and without abnormal thyroid function.

Insulin-dependent diabetes mellitus probands from the Familial Autoimmune and Diabetes Study were evaluated for autoimmune thyroid disease (n = 265). The prevalence of Hashimoto's thyroiditis was 26.6%; 42.0% of these individuals were euthyroid, and 58.0% were hypothyroid. There was a female predominance among hypothyroid and euthyroid Hashimoto's cases compared to those with no thyroid disease (75% vs. 72.4% vs. 41.6%; P < 0.001). Insulin-dependent diabetes mellitus patients with hypothyroid Hashimoto's thyroiditis were more likely to report another autoimmune disease compared to euthyroid Hashimoto's patients or individuals with no thyroid disease (30.8% vs. 17.2% vs. 13.9%; P < 0.01). Sex-specific analysis revealed that this difference was significant for men but not for women. Both euthyroid and hypothyroid Hashimoto's cases were more likely to have a family history of the disease (66.7% vs. 69.2% vs. 47.7%; P < 0.05). No differences were observed in the prevalence of DQA1*0501-DQB1*0201 or DQA1*0301-DQB1*0302 across the three groups. Body mass index, lipid levels, glycemic control, and diabetes complications were also similar. However, euthyroid Hashimoto's women were more likely to report spontaneous abortions than those with hypothyroid Hashimoto's thyroiditis or no thyroid disease (23.8% vs. 61.5% vs. 29.1%; P < 0.05). These data suggest that gender-specific risk factors may be primary determinants of Hashimoto's thyroiditis and other autoimmune diseases among women. However, disease-specific determinants may also increase susceptibility to other autoimmune diseases.

MR and conventional angiography: work in progress toward assessing utility in radiology.

RATIONALE AND OBJECTIVES: The authors assessed health-related quality of life changes associated with peripheral x-ray angiography and magnetic resonance (MR) angiography. MATERIALS AND METHODS: Utility (the desirability or preference that individuals exhibit for a particular health state) was assessed in 30 patients with peripheral vascular disease referred for angiography by using a rating scale, additional categoric scaling questions to separate preference from experience, a willingness-to-pay technique, functional and cognitive status questions, and a time trade-off technique. All patients underwent both MR angiography and x-ray angiography. RESULTS: Patients reported significantly (P < .05) less anxiety after the test, less pain after the test, fewer new physical limitations, and less effect on performance of daily activities with MR angiography. Findings from the overall rating scale and categoric scaling questions also significantly (P < .05) favored MR angiography. Patients were willing to pay a mean of 2.12% of annual income to avoid MR angiography and a mean of 7.41% to avoid x-ray angiography. The median quality-adjusted life gain required by patients to undergo the procedures was 52.5-60 days for x-ray angiography and 10.5 days for MR angiography, without discounting. CONCLUSION: X-ray angiography has more profound short-term adverse effects on life than does MR angiography. Preference-based measures can be adapted to elicit patient values for short-term health states as seen in radiology.

Molecular epidemiology of autoimmune thyroid disease.

This paper presents preliminary data regarding the prevalence and risk factors for autoimmune thyroid disease in IDDM probands ascertained from the Children's Hospital of Pittsburgh IDDM Registry for 1950-1965 (n = 669). Living IDDM probands who participated in the 1990 follow-up survey (n = 380) were recruited for the Familial Autoimmune and Diabetes Study. Siblings and parents were also invited to participate. To date, 255 IDDM probands and 597 parents and siblings have been evaluated. The diagnosis of autoimmune thyroid disease was based on a clinical evaluation, medical history, and laboratory determinations. Graves disease was rare in this cohort (n = 5). However, Hashimoto's thyroiditis was common among women. Prevalence rates ranged from 54% for IDDM women age < 40 years to 75% for those > 50 years. Corresponding age-specific estimates for female relatives were 22% and 44%, respectively. Approximately one-half of the Hashimoto's individuals were euthyroid; they were more likely to have other autoantibodies and a positive family history than those who were hypothyroid or had no thyroid disease. Genetic analyses revealed a 2-fold increase in DQA1*0501-DQB1*0201 among the Hashimoto's compared to the non-Hashimoto's haplotypes. These findings suggested that Hashimoto's thyroiditis was common in IDDM families, which may be due, in part, to common disease susceptibility genes.

MR angiography with three-dimensional MR digital subtraction angiography.

We have developed a time-resolved, contrast-enhanced, volume-imaging technique for magnetic resonance (MR) angiography, known as three-dimensional (3D) MR digital subtraction angiography (DSA). This technique greatly improves MR angiogram quality because it combines the injection of a contrast agent with the ability to image the temporal passage of this agent and, thereby, obviates the need for timing scans or other complicated synchronization schemes. Three-dimensional MR DSA also represents a potential improvement in the sense that, relative to DSA and computed tomography (CT) angiography, the contrast agent is less toxic. Additionally, unlike CT angiography, images may be acquired during the passage of the contrast agent. Therefore, 3D MR DSA shows the sequential passage of contrast through the arterial and venous system, followed by uptake in various organs. Unlike conventional DSA, 3D MR DSA imaging acquires full volume datasets, which allows subsequent reprojection and reformatting. Because images are obtained at approximately 2-6 s time intervals using a temporal aperture on the order of several seconds, motion (such as respiration) causes only a temporary disruption of image quality, similar to that observed in MR fluoroscopy. These temporal characteristics also make the proposed sequence insensitive to variations in the shape and timing of the contrast-pass curve. Although the individual time-resolved images will have somewhat decreased signal-to-noise ratio (SNR) relative to nontime-resolved scans collected in the same acquisition time, the SNR improvement due to the gadolinium appears to accommodate this trade-off. Additionally, if motion between successive images is small, then the full suite of temporal processing schemes, previously investigated in connection with DSA and time-resolved two-dimensional (2D) MR, such as mask mode subtraction, simple matched filtering and Eigen filtering, can be used to obtain composite images. These derived images generally have an increased SNR or negligible venous signal if an arterial-phase image is not obtained in the early time-resolved images. In summary, 3D MR DSA will significantly advance MR angiography because of the following intrinsic advantages: (1) improved signal-to-noise, (2) scan orientation may be chosen independently of the direction of blood flow, (3) uniform vascular signal, even from regions of complex flow, (4) minimization of motion artifacts, (5) greatly reduced sensitivity to variation in the shape and timing of the contrast bolus, (6) ability to be reformatted or reprojected, and (7) ability to apply a variety of temporal postprocessing techniques.