Assessment of the hepatic veins in poor contrast conditions using dual energy CT: evaluation of a novel monoenergetic extrapolation software algorithm.

PURPOSE: To evaluate a novel monoenergetic post-processing algorithm (MEI+) in patients with poor intrahepatic contrast enhancement. MATERIALS AND METHODS: 25 patients were retrospectively included in this study. Late-phase imaging of the upper abdomen, which was acquired in dual-energy mode (100/140 kV), was used as a model for poor intrahepatic contrast enhancement. Traditional monoenergetic images (MEI), linearly weighted mixed images with different mixing ratios (MI), sole 100 and 140 kV and MEI+ images were calculated. MEI+ is a novel technique which applies frequency-based mixing of the low keV images and an image of optimal keV from a noise perspective to combine the benefits of both image stacks. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the intrahepatic vasculature (IHV) and liver parenchyma (LP) were objectively measured and depiction of IHV was subjectively rated and correlated with portal venous imaging by two readers in consensus. RESULTS: MEI+ was able to increase the SNR of the IHV (5.7 ±â€Š0.4 at 40keV) and LP (4.9 ±â€Š1.0 at 90keV) and CNR (2.1 ±â€Š0.6 at 40keV) greatly compared to MEI (5.1 ±â€Š1.1 at 80keV, 4.7 ±â€Š1.0 at 80keV, 1.0 ±â€Š0.4 at 70keV), MI (5.2 ±â€Š1.1 M5:5, 4.8 ±â€Š1.0 M5:5, 1.0 ±â€Š3.5 M9:1), sole 100 kV images (4.4 ±â€Š1.0, 3.7 ±â€Š0.8, 1.0 ±â€Š0.3) and 140 kV images (2.8 ±â€Š0.5, 3.1 ±â€Š0.6, 0.1 ±â€Š0.2). Subjective assessment rated MEI+ of virtual 40 keV superior to all other images. CONCLUSION: MEI+ is a very promising algorithm for monoenergetic extrapolation which is able to overcome noise limitations associated with traditional monoenergetic techniques at low virtual keV levels and consequently does not suffer from a decline of SNR and CNR at low keV values. This algorithm allows an improvement of IHV depiction in the presence of poor contrast. KEY POINTS: • The evaluated new image-based algorithm for virtual monoenergetic imaging allows calculating low virtual keV images from dual energy datasets with significantly improved contrast-to-noise ratios. • The image based novel monoenergetic extrapolation algorithm applies frequency-based mixing of the low keV images and an image of optimal keV from a noise perspective to combine the benefits of both image stacks.• When compared to traditional monoenergetic images, the novel monoenergetic algorithm has improved contrast-to-noise ratios for both low and high virtual keV images.• Contrast-enhanced dual energy images with poor contrast conditions can be significantly improved, e.g. late phase imaging of the liver.

High-pitch dual-source CT angiography of supra-aortic arteries: assessment of image quality and radiation dose.

INTRODUCTION: High-pitch CT angiography (CTA) is a recent innovation that allows significant shortening of scan time with volume coverage of 43 mm per second. The aim of our study was to assess this technique in CTA of the head and neck. METHODS: CTA of supra-aortic arteries was performed in 50 patients using two acquisition protocols: conventional single-source 64-slice (pitch 1.2) and high-pitch dual-source 128-slice CT (pitch 3.2). Subjective and objective image quality of supra-aortic vessel ostia as well as intra- and extra-cranial segments was retrospectively assessed by blinded readers and radiation dose compared between the two protocols. RESULTS: Conventional and high-pitch CTA achieved comparable signal-to-noise ratios in arterial (54.3 ± 16.5 versus 57.3 ± 14.8; p = 0.50) and venous segments (15.8 ± 6.7 versus 18.9 ± 8.9; p = 0.21). High-pitch scanning was, however, associated with sharper delineation of vessel contours and image quality significantly improved at the level of supra-aortic vessel ostia (p < 0.0001) as well as along the brachiocephalic trunk (p < 0.0001), the subclavian arteries (p < 0.0001), proximal common carotid arteries (p = 0.01), and vertebral V1 segments (p < 0.0001). Using the high-pitch mode, the dose-length product was reduced by about 35% (218.2 ± 30 versus 141.8 ± 20 mGy × cm). CONCLUSIONS: Due to elimination of transmitted cardiac motion, high-pitch CTA of the neck improves image quality in the proximity of the aortic arch while significantly lowering radiation dose. The technique thus qualifies as a promising alternative to conventional spiral CTA and may be particularly useful for identification of ostial stenosis.

Dual energy CTA of the carotid bifurcation: advantage of plaque subtraction for assessment of grade of the stenosis and morphology.

OBJECTIVES: Calcifications adjacent to the vessel lumen often limit the assessment of stenoses at the carotid bifurcation in 3D multi intensity projection images (3D-MIP) using conventional single energy CT. Aim of the study was to evaluate the diagnostic value of 3D-MIP images after subtraction of bone and calcified plaques (PBS) using dual energy CT for the assessment of carotid bifurcation stenoses. MATERIALS AND METHODS: 36 patients with a total of 46 stenoses at the carotid bifurcation were examined with a dual energy CT system. Grade of the stenoses and plaque morphology were assessed in axial multi planar projections (axMPR) and freely rotatable 3D-MIP images before and after PBS and compared with results from DSA. RESULTS: Grade of the stenosis could be evaluated in all 46 cases in DSA, axMPR and 3D-MIP after PBS. However, in 25 cases grade of the stenosis was not assessable prior to PBS. The average grade of the stenosis increased from DSA (81.4%) to axMPR (83.5%) to 3D-MIP before and after PBS (86.5% and 85.6%). The amount of pseudo-occlusions increased in concordance with the grade of the stenosis (0<9<16). Using 3D-MIP reconstructions, plaque morphology could be evaluated in 32/46 stenoses before PBS and in 44/46 cases after PBS. CONCLUSIONS: PBS facilitated the evaluation of grade of the stenosis in all cases. Nevertheless, after PBS stenoses were overrated in 3D-MIP in comparison to DSA and axMPR. Moreover, plaque morphology, as an independent risk factor for stroke, can be evaluated even in calcified plaques after PBS. Therefore dual energy CTA with plaque subtraction has the potential to identify patients with vulnerable plaques better than conventional CTA.

Prospective randomized trial comparing the outcome and cost of in vitro fertilization with that of a traditional treatment algorithm as first-line therapy for couples with infertility.

OBJECTIVE: To determine whether IVF or a standard infertility treatment algorithm results in better outcome and/or lower cost when used as first-line therapy for couples with infertility. DESIGN: Prospective, randomized clinical study. SETTING: University-affiliated infertility clinic. PATIENT(S): Couples with newly diagnosed infertility and no prior treatment. INTERVENTION(S): Couples were randomized to undergo either IVF (group 1, n = 46) or a standard infertility treatment algorithm (group 2, n = 50) as initial therapy for infertility. MAIN OUTCOME MEASURE(S): Pregnancy rates and costs per couple, per month of treatment, and per pregnancy. RESULT(S): Pregnancy rates were higher in group 2 than in group 1. Costs per couple were not statistically different, although a trend toward higher costs was apparent in group 1, reflected by a higher median cost per clinical pregnancy established and a higher cost per month of treatment. Whereas cost differences between the groups diminished over time, pregnancy rates remained the same. CONCLUSION(S): In vitro fertilization currently does not represent an appropriate first-line treatment option for couples with infertility. The use of a standard infertility treatment algorithm results in a higher pregnancy rate and lower cost and therefore should be the preferred treatment approach.

Operations for stress urinary incontinence in the United States, 1988-1992.

OBJECTIVES: To determine the frequency and cost of operations for stress urinary incontinence in the United States. METHODS: We reviewed data from the 1988-1992 National Hospital Discharge Surveys and the 1991 California Office of Statewide Health Planning Survey. We determined the frequency and type of surgical procedures performed for stress urinary incontinence and estimated the total direct costs of these operations in the United States. RESULTS: From 1988 to 1992, the total number of operations for stress incontinence increased from 78,000 to over 100,000. The rate of operations increased most in women older than 65 years of age. The total direct cost for treatment of stress urinary incontinence in the United States in 1991 was about $0.5 billion. CONCLUSIONS: Operations for treatment of stress urinary incontinence are increasing in frequency in the United States. They are both more commonly performed and more costly than have been previously reported.

Myocardial m-[123I]iodobenzylguanidine scintigraphy for the assessment of adrenergic cardiac innervation in patients with IDDM. Comparison with cardiovascular reflex tests and relationship to left ventricular function.

Cardiac imaging using m-[123I]iodobenzylguanidine (mIBG) reflects sympathetic myocardial innervation. In patients with insulin-dependent diabetes mellitus (IDDM), the following were studied: 1) the prevalence of derangements of cardiac autonomic innervation as detected by mIBG scintigraphy in comparison with cardiovascular reflex tests and 2) the relationship between adrenergic cardiac innervation and left ventricular (LV) function. Twenty-four patients with IDDM without overt heart disease were studied after silent coronary artery disease was excluded by 201Tl scintigraphy. Cardiac innervation was evaluated by both mIBG scintigraphy (tomographic imaging) and cardiovascular reflex tests. Systolic (ejection fraction [EF] percentage) and diastolic (peak filling rate [PFR] defined as end-diastolic volumes per second [EDV/s]) LV function were determined by equilibrium radionuclide angiography at rest and during bicycle exercise. mIBG scintigraphy was also performed in 10 control subjects. All control subjects exhibited a normal myocardial mIBG distribution. Among diabetic patients, only six had normal mIBG scans (group 1), whereas 18 had evidence of regional adrenergic denervation (group 2). Reflex tests suggested cardiac autonomic neuropathy in only seven of these patients (P < 0.01 vs. mIBG). All patients had a normal EF at rest. However, group 2 showed an impaired response to exercise as indicated by a smaller increase in EF (5 +/- 6 vs. 13 +/- 5%, P < 0.05) and a lower PFR (5.9 +/- 0.8 vs. 7.3 +/- 1.2 EDV/s, P < 0.01). Myocardial mIBG scintigraphy reveals that in patients with IDDM, sympathetic myocardial dysinnervation is much more common than previously thought. Furthermore, subclinical LV dysfunction is related to derangements of adrenergic cardiac innervation.

Dose linearity assessment of glimepiride (Amaryl) tablets in healthy volunteers.

Twelve healthy fasting male volunteers received glimepiride in 1, 2, 4 or 8 mg single oral doses. On the days when glimepiride was taken, the subjects were given a standardised carbohydrate diet (18 bread exchange units) and drank 125 ml of water hourly. Blood and urine samples were taken before drug administration and afterwards for up to 36 hours (blood) and 48 hours (urine) to determine serum and urinary concentrations of glimepiride and its hydroxy- and carboxy-metabolites (M1 and M2). The areas under the curve for glimepiride after oral doses of 1 to 8 mg and the urinary recovery of its metabolites M1 and M2 were dose linear. All confidence intervals were well contained within the bioequivalence range of 80-125%. There was a statistically significant difference for Cmax values of glimepiride between doses after dose normalisation. A dose-dependent increase for Cmax was nevertheless clearly observed with a correlation coefficient of r=0.90. The pharmacokinetics of glimepiride are dose linear in the dose range 1 to 8 mg, and glimepiride was safe and well tolerated in healthy volunteers.

Case management and quality of care for diabetic patients.

Increasing clinical demand for medical services in an environment of limited financial resources to reimburse for such services has lead to the evolution of case management processes. They may be defined as processes that help achieve the best possible clinical outcome for a patient at a cost that represents the best value to the patient and benefit plan. The most responsive and sensitive execution of a case management process is one that includes a high level of physician peer review. This type of case management may enhance the quality of care rendered to diabetic and other patients. Care that is neither necessary nor appropriate cannot be considered quality, no matter who renders it, nor how good the outcome. A case management process that focuses on medical necessity and seeks flexibility from patients, physicians, providers, and payors can help to maintain appropriate high-quality care with costs that, over time, deliver value to all participants in the process. The execution of, and the elements contained within, a clinically sensitive case management process is briefly discussed.

A national perspective on UR (utilization review).

Quality of care is the responsibility of each and every attending physician. There are many definitions of quality, none of which encompasses the universe of medical practice. Care that is neither medically necessary nor appropriate can never be considered good, no matter who renders it or how good the outcome. It is upon these premises that utilization review firms focus.