Single-source dual-energy spectral multidetector CT of pancreatic adenocarcinoma: optimization of energy level viewing significantly increases lesion contrast.

AIM: To evaluate lesion contrast in pancreatic adenocarcinoma patients using spectral multidetector computed tomography (MDCT) analysis. MATERIALS AND METHODS: The present institutional review board-approved, Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant retrospective study evaluated 64 consecutive adults with pancreatic adenocarcinoma examined using a standardized, multiphasic protocol on a single-source, dual-energy MDCT system. Pancreatic phase images (35 s) were acquired in dual-energy mode; unenhanced and portal venous phases used standard MDCT. Lesion contrast was evaluated on an independent workstation using dual-energy analysis software, comparing tumour to non-tumoural pancreas attenuation (HU) differences and tumour diameter at three energy levels: 70 keV; individual subject-optimized viewing energy level (based on the maximum contrast-to-noise ratio, CNR); and 45 keV. The image noise was measured for the same three energies. Differences in lesion contrast, diameter, and noise between the different energy levels were analysed using analysis of variance (ANOVA). Quantitative differences in contrast gain between 70 keV and CNR-optimized viewing energies, and between CNR-optimized and 45 keV were compared using the paired t-test. RESULTS: Thirty-four women and 30 men (mean age 68 years) had a mean tumour diameter of 3.6 cm. The median optimized energy level was 50 keV (range 40-77). The mean ± SD lesion contrast values (non-tumoural pancreas - tumour attenuation) were: 57 ± 29, 115 ± 70, and 146 ± 74 HU (p = 0.0005); the lengths of the tumours were: 3.6, 3.3, and 3.1 cm, respectively (p = 0.026); and the contrast to noise ratios were: 24 ± 7, 39 ± 12, and 59 ± 17 (p = 0.0005) for 70 keV, the optimized energy level, and 45 keV, respectively. For individuals, the mean ± SD contrast gain from 70 keV to the optimized energy level was 59 ± 45 HU; and the mean ± SD contrast gain from the optimized energy level to 45 keV was 31 ± 25 HU (p = 0.007). CONCLUSION: Significantly increased pancreatic lesion contrast was noted at lower viewing energies using spectral MDCT. Individual patient CNR-optimized energy level images have the potential to improve lesion conspicuity.

Transesophageal echocardiographic identification of a descending aortic aneurysm rupture into the left lung.

This case report describes a patient in whom a descending aortic aneurysm ruptured into the left lung, producing hemoptysis. With transesophageal echocardiography, we were able to define the site and extent of the aneurysm, as well as the two sites of rupture into lung tissue.

Doppler sonographic enhancement of hepatic hemangiomas and hepatocellular carcinomas after perflenapent emulsion: preliminary study.

Ultrasonographic microbubble contrast agents improve Doppler signals by increasing blood backscatter. We retrospectively reviewed our experience with perflenapent (EchoGen), an emulsion of liquid dodecafluoropentane, in the evaluation of 13 patients with focal hepatic lesions (10 hemangiomas and six hepatocellular carcinomas). Perflenapent improved the detection of color Doppler flow signals within the lesions. The hemangiomas showed peripheral nonpulsatile signals and the hepatocellular carcinomas showed more diffuse enhancement with both arterial and venous type signals. This preliminary study suggests that perflenapent administration may aid in the sonographic differentiation of these focal lesions.

A radiology department intranet: development and applications.

An intranet is a "private Internet" that uses the protocols of the World Wide Web to share information resources within a company or with the company's business partners and clients. The hardware requirements for an intranet begin with a dedicated Web server permanently connected to the departmental network. The heart of a Web server is the hypertext transfer protocol (HTTP) service, which receives a page request from a client's browser and transmits the page back to the client. Although knowledge of hypertext markup language (HTML) is not essential for authoring a Web page, a working familiarity with HTML is useful, as is knowledge of programming and database management. Security can be ensured by using scripts to write information in hidden fields or by means of "cookies." Interfacing databases and database management systems with the Web server and conforming the user interface to HTML syntax can be achieved by means of the common gateway interface (CGI), Active Server Pages (ASP), or other methods. An intranet in a radiology department could include the following types of content: on-call schedules, work schedules and a calendar, a personnel directory, resident resources, memorandums and discussion groups, software for a radiology information system, and databases.

The year 2000 threat: preparing radiology for nine realms of risk.

The year 2000 computer problem arises from a long-standing and often-duplicated computer programming error. Affected programs use only two digits to represent years, which may lead to a variety of computer malfunctions and data errors related to crossing from 1999 (99) to 2000 (00), at which point computers may interpret 00 as 1900 or other incorrect dates. Radiology and medicine may be seriously affected by this problem as it relates to the function of its equipment; business functions such as scheduling, billing and purchasing; the reliability of infrastructure such as power and telecommunications; the availability of supplies; and many other issues. It is crucial that radiologists, as practitioners of one of the most computer-oriented medical specialties, help lead the effort to ensure continuity of operations as the year 2000 boundary approaches and passes. This article provides suggestions for a structured approach, as well as tools and checklists, to guide project leaders attempting to identify and remediate year 2000-associated problems within radiology facilities.

PACS and CR implementation in a level I trauma center emergency department.

Implementation of a picture archive and communication system (PACS) at a large teaching hospital is an expensive and daunting endeavor. The approach taken at the University of Alabama Hospitals has been to assemble an institution-wide system through focused integration of smaller mini-PACS. Recently a mini-PACS using Computed Radiography (CR) has been placed in the Emergency Department (ED) of a Level I Trauma Center completely replacing conventional screen-film radiography. This area of the hospital produces approximately 250 images per day and provided many challenging requirements: the need for rapid radiography; providing good image quality for difficult examinations with potentially uncooperative patients; reproduction of lost films to maintain availability of images to multiple consulting teams; and frequently unknown patient demographics. The PACS includes both vendor-supplied and in-house developed devices for image storage, distribution, and display. Digital images are produced using two photo-stimulable phosphor CR systems. Currently, all radiographic examinations are acquired digitally with production of a hard copy film as well as electronic distribution via the PACS. Interpretation of images is done primarily via hard copy with a goal of transition to soft copy interpretation. This paper discusses the functional requirements of the PACS and solutions to workflow issues arising in the ED.

Slip-ring and conventional dynamic hepatic CT: contrast material and timing considerations.

The major conclusions and recommendations of this review of contrast material use are summarized as follows: 1. Our recommendations for routine administration of contrast material are summarized in the Table. 2. Patient factors, such as weight, and liver and cardiovascular disorders may be taken into account when the above recommendations are modified. 3. Unenhanced scanning should be performed selectively. It is unnecessary for routine examinations performed with modern scanners and good contrast material injection techniques. 4. Although conclusive evidence is lacking regarding efficacy, reduced doses of contrast material may be given to patients with an elevated serum creatinine level. A full dose of low-osmolar contrast material may be given to functionally anephric patients if otherwise medically appropriate. 5. Differences in enhancement patterns produced by low-osmolar contrast agents and by high-osmolar contrast agents are small. Choice of contrast material should be based on other factors. 6. The dose of low-osmolar contrast material may be lower than the dose of high-osmolar contrast material so the examination cost may be reduced. 7. Low-osmolar contrast material is not satisfactory to use with delayed iodine scanning. 8. With use of slip-ring scanners and either helical or incremented scanning and recommended techniques, scanning should begin by the end of the injection of contrast material for biphasic techniques and within about 5-15 seconds after the end of injection for monophasic techniques. 9. Section thicknesses no greater than 8 mm should be used for helical or nonhelical scanning. 10. With helical scanning, a 1:1 pitch is preferred with a thickness of 5-8 mm. Overlapping sections may be used selectively to help identify and characterize small lesions. 11. Multiple-pass scanning is helpful to identify hepatocellular carcinoma in cirrhotic livers. This technique may also prove helpful in other conditions. As with any new technology, considerable advantages have come with new challenges, which can be overcome by knowing underlying principles and by attending to detail. Although we have learned much over the past 15 years about proper performance of abdominal CT examinations, we have much yet to learn about the effects of such examinations on the improved health of our patients and on the economic costs to society of providing this form of health care. Opinions on techniques have converged recently, as summarized herein. Therefore, we hope that some centers will now redirect their CT research toward the profoundly difficult, timely, and important issues of examination appropriateness, the value of quality improvement programs, clinical outcomes, and cost-effectiveness.

Sonography by the radiologist: self-referral, turf battles, and marketing.

Competition between radiologists and nonradiologists for the performance and billing of radiologic imaging examinations is, perhaps, most pervasive in the field of diagnostic sonography [1-3]. The purpose of this article is to help radiologists understand and deal with turf battles and the self-referral of clinicians and to describe marketing analyses and strategy that can be useful when attempting to decrease competition and increase referrals.

Estimation of computerized tomography derived abdominal fat distribution.

Measurements of intra-abdominal fat (IAF) may be important since it is associated with numerous metabolic disorders. The relationship between computerized tomography (CT) measured fat distribution and densitometry measures was investigated in a sample of 61 male Caucasian subjects, aged 18 to 30 years with varying adiposity. Regression models were developed for estimating CT-derived fat of 40 men to estimate IAF. Two equations were developed to estimate IAF. The first used only anthropometric measures. Waist circumference and log chest ratio entered the equation and accounted for 67% of the variance. The second model included densitometry-measured percentage fat with the centred product of waist and hip circumferences, accounting for 73% of the variance. Regression equations were also developed to estimate subcutaneous fat area so that the ratio of IAF to subcutaneous fat might be estimated. Although subcutaneous fat could be estimated, the ratio between IAF and subcutaneous fat could not be estimated accurately. A validation of all regression equations developed for male subjects who also completed using a separate validation sample (n = 21). Only the studies with sample characteristics similar to those found in the validation sample validated satisfactorily. Results indicate that anthropometric and densitometry measures cannot be used to estimate CT-derived abdominal fat with precision, however they may be of value in health risk screening of individuals with high levels of IAF. Proper selection procedures with regard to age, adiposity, and morbidity must be used.

Effect of varying rates of low-osmolarity contrast media injection for hepatic CT: correlation with indocyanine green transit time.

Contrast enhancement in hepatic computed tomography (CT) is related to multiple factors, including the amount of iodine injected, the rate of injection, and body weight. Fifty patients were randomized into two groups: 19 patients (group 1) received a 160-mL dose of Optiray 320 (ioversol) at 3.0 mL/sec, and 31 (group 2) received the same dose at 4.5 mL/sec. Indocyanine green dye transit time, peak enhancement, delayed enhancement, time to peak enhancement, age, and weight were statistically analyzed. Time to peak enhancement was significantly shorter in group 2 than in group 1 (62 seconds vs 73 seconds, respectively; P less than .01). Peak contrast enhancement averaged 88 HU +/- 19 in group 1 and 99 HU +/- 17 in group 2 (P = .06). Circulation time did not correlate with peak enhancement and thus does not assist in tailoring contrast medium injection for hepatic CT. Injection of contrast material at 3.0 and 4.5 mL/sec provides greater hepatic CT contrast enhancement than previously reported, with no significant risk of subcutaneous extravasation when injection is monitored carefully. These higher levels of contrast enhancement may assist in detecting and characterizing hepatic lesions.

Duplex assessment of the portal venous system.

The clinical applications of duplex ultrasound and color Doppler imaging in the evaluation of the portal venous system and hepatic vasculature are quite diverse and widespread. These include identification of portal vein thrombosis, portal venous hypertension, and hepatic veno-occlusive disease as well as a role in the preoperative and postoperative treatment of patients who are candidates for portosystemic shunts or for liver allografts. As technological improvements continue, the current applications will almost certainly be refined, with resultant improvements in sensitivity, specificities, and accuracy rates.

Duplex assessment of the splanchnic vasculature.

The role of duplex ultrasound and color Doppler imaging in the evaluation of patients with suspected splanchnic vasculature obstructive disease and chronic mesenteric ischemia is not clearly defined. In this report the examination technique, as well as normal and abnormal findings, is discussed. Limitations are also described.

Duplex evaluation of native renal vessels and renal allografts.

Duplex ultrasound and color duplex imaging are useful in evaluating the renal vasculature. Investigation of native renal vessels includes the diagnosis of renal artery stenosis and occlusion and renal vein thrombosis. The sonographic examination of renal allografts may detect vascular complications and peritransplant fluid collections, both of which may impair allograft function. In order to perform and interpret renal vascular sonography, knowledge of pertinent vascular anatomy and proper duplex technique is essential. Renal arterial and venous examination with gray-scale, Doppler, and color duplex imaging is reviewed, comparing their performance with other methods of assessing renal vessels when appropriate.

Peripheral arterial occlusive disease: prospective comparison of MR angiography and color duplex US with conventional angiography.

Conventional angiography, two-dimensional inflow magnetic resonance (MR) angiography, and color duplex ultrasound (US) were performed on 12 patients in a blinded, prospective study. The ability to grade arterial lesions and plan revascularization interventions were compared. Arterial lesions were categorized as nonsignificant (0%-49% diameter reduction) or significant (50%-100% diameter reduction). Determination of nonsignificant and significant lesions with MR angiography was in agreement with that at conventional angiography in 100 of 140 lesions (71%). Agreement between results of conventional angiography and color duplex US occurred with 114 of 123 infrainguinal lesions (93%). Twenty-one vascular interventions were planned by using conventional angiography; there was agreement with color duplex US in 11 cases and MR angiography in five. Color duplex US performed well in the assessment of infrainguinal disease but was limited in the evaluation of iliac segments because of nonvisualization. The iliac region was visualized in more patients with MR angiography than with color duplex US, but image quality with MR angiography was inconsistent. Strategies to improve MR angiography of the peripheral vasculature merit further study.

Renal artery stenosis: prospective evaluation of diagnosis with color duplex US compared with angiography. Work in progress.

A prospective, double-blind comparison of color duplex sonography with angiography was performed for diagnosing renal artery stenosis in 50 kidneys in 26 patients. The major criterion for diagnosing a diameter narrowing of more than 50% was a velocity of greater than 100 cm/sec. Angiography demonstrated 10 stenoses and one occlusion in main or accessory renal arteries in seven patients. Twenty-two percent of kidneys had accessory renal arteries. Color duplex scanning helped identify 58% of the main arteries and no accessory vessels. None of the stenotic vessels were identified with duplex scanning, but the single occluded vessel was correctly diagnosed. Nine of the 29 vessels identified with duplex scanning were incorrectly diagnosed as stenotic, findings yielding a specificity of 37%. The authors conclude that the published velocity threshold of 100 cm/sec is too low. Duplex scanning with current technology is unlikely to prove satisfactory for screening patients with hypertension for renal artery stenosis.

Small aorta: CT detection and clinical significance.

Small aortas were documented by CT in six patients, 16-34 years old. The diameter of these aortas measured at the level of 1 cm below the orifice of the superior mesenteric artery ranged from 10 to 12 mm, much smaller than the mean of 17 mm obtained from 20 subjects, 16-20 years old. Such small aortas are usually produced by vasoconstriction as a compensatory response to hypovolemic shock.