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Objectives: To further reduce the contrast medium (CM) dose of full aortic CT angiography (ACTA) imaging using the augmented cycle-consistent adversarial framework (Au-CycleGAN) algorithm. Methods: We prospectively enrolled 150 consecutive patients with suspected aortic disease. All received ACTA scans of ultra-low-dose CM (ULDCM) protocol and low-dose CM (LDCM) protocol. These data were randomly assigned to the training datasets (n = 100) and the validation datasets (n = 50). The ULDCM images were reconstructed by the Au-CycleGAN algorithm. Then, the AI-based ULDCM images were compared with LDCM images in terms of image quality and diagnostic accuracy. Results: The mean image quality score of each location in the AI-based ULDCM group was higher than that in the ULDCM group but a little lower than that in the LDCM group (all p < 0.05). All AI-based ULDCM images met the diagnostic requirements (score ≥ 3). Except for the image noise, the AI-based ULDCM images had higher attenuation value than the ULDCM and LDCM images as well as higher SNR and CNR in all locations of the aorta analyzed (all p < 0.05). Similar results were also seen in obese patients (BMI > 25, all p < 0.05). Using the findings of LDCM images as the reference, the AI-based ULDCM images showed good diagnostic parameters and no significant differences in any of the analyzed aortic disease diagnoses (all K-values > 0.80, p < 0.05). Conclusions: The required dose of CM for full ACTA imaging can be reduced to one-third of the CM dose of the LDCM protocol while maintaining image quality and diagnostic accuracy using the Au-CycleGAN algorithm. Key Points: • The required dose of contrast medium (CM) for full ACTA imaging can be reduced to one-third of the CM dose of the low-dose contrast medium (LDCM) protocol using the Au-CycleGAN algorithm. • Except for the image noise, the AI-based ultra-low-dose contrast medium (ULDCM) images had better quantitative image quality parameters than the ULDCM and LDCM images. • No significant diagnostic differences were noted between the AI-based ULDCM and LDCM images regarding all the analyzed aortic disease diagnoses. [ABSTRACT FROM AUTHOR]

Objectives: To determine whether intravenous iodinated contrast material administration increases the risk of acute kidney injury (AKI) in patients with nephrotic syndrome undergoing contrast-enhanced CT.Methods: Patients with nephrotic syndrome undergoing contrast-enhanced CT were retrospectively identified (n = 701). Control group consisted of patients with nephrotic syndrome receiving non-contrast CT (n = 1053). Two different 1:1 propensity score matching models using three or 10 variables were developed for each estimated glomerular filtration (eGFR) subgroup. Incidence of post-CT AKI for the two groups was assessed and compared by standard AKI criteria and Acute Kidney Injury Network (AKIN) criteria.Results: After matching with three variables, the AKI incidence in the contrast-enhanced CT and non-contrast CT groups was 2.7% vs 2.5% (standard AKI criteria) and 4.2% vs. 6.7% (AKIN criteria) (p = 1.00 and 0.05), respectively. After matching with 10 variables, AKI incidences were 3.1% vs. 2.6% (standard AKI criteria) and 4.1% vs. 7.4% (AKIN criteria) (p = 0.72 and 0.03), respectively. AKI incidences of each eGFR subgroup in the contrast-enhanced CT group were not higher than in the non-contrast CT group (lowest p = 0.46).Conclusion: Intravenous contrast material administration during CT was not found to be a risk factor for AKI in this large cohort of patients with nephrotic syndrome.Key Points: • AKI incidence of contrast-enhanced CT and non-contrast CT had no difference. • AKI incidences of eGFR subgroup in contrast-enhanced CT were not increased. • Studies without a non-contrast CT control group may overestimate CIN incidence. [ABSTRACT FROM AUTHOR]

Purpose: To investigate feasibility, image quality and safety of low-tube-voltage, low-contrast-volume comprehensive cardiac and aortoiliac CT angiography (CTA) for planning transcatheter aortic valve replacement (TAVR).Materials and Methods: Forty consecutive TAVR candidates prospectively underwent combined CTA of the aortic root and vascular access route (270 mgI/ml iodixanol). Patients were assigned to group A (second-generation dual-source CT [DSCT], 100 kV, 60 ml contrast, 4.0 ml/s flow rate) or group B (third-generation DSCT, 70 kV, 40 ml contrast, 2.5 ml/s flow rate). Vascular attenuation, noise, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were compared. Subjective image quality was assessed by two observers. Estimated glomerular filtration (eGFR) at CTA and follow-up were measured.Results: Besides a higher body-mass-index in group B (24.8±3.8 kg/m2 vs. 28.1±5.4 kg/m2, P=0.0339), patient characteristics between groups were similar (P≥0.0922). Aortoiliac SNR (P=0.0003) was higher in group B. Cardiac SNR (P=0.0003) and CNR (P=0.0181) were higher in group A. Subjective image quality was similar (P≥0.213) except for aortoiliac image noise (4.42 vs. 4.12, P=0.0374). TAVR-planning measurements were successfully obtained in all patients. There were no significant changes in eGFR among and between groups during follow-up (P≥0.302).Conclusion: TAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low contrast volume using low-tube-voltage acquisition.Key Points: • Third-generation dual-source CT facilitates low-tube-voltage acquisition. • TAVR planning can be performed with reduced contrast volume and radiation dose. • TAVR-planning CT did not result in changes in creatinine levels at follow-up. • TAVR candidates can be safely evaluated by comprehensive low-tube-voltage CT angiography. [ABSTRACT FROM AUTHOR]

Objectives: To validate two previously presented models containing risk factors to identify patients with estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 or eGFR <45 ml/min/1.73 m2.Methods: In random patients undergoing intravenous contrast-enhanced computed tomography (CECT) the following risk factors were assessed: history of urological/nephrological disease, hypertension, diabetes mellitus, anaemia, congestive heart failure, other cardiovascular disease or multiple myeloma or Waldenström disease. Data on kidney function, age, gender and type and indication of CECT were also registered. We studied two models: model A-diabetes mellitus, history of urological/nephrological disease, cardiovascular disease, hypertension; model B-diabetes mellitus, history of urological/nephrological disease, age >75 years and congestive heart failure. For each model, associations with eGFR <60 ml/min/1.73 m2 or eGFR <45 ml/min/1.73 m2 was studied.Results: A total of 1,001 patients, mean age 60.36 years were included. In total, 92 (9.2 %) patients had an eGFR <60 ml/min/1.73 m2 and 11 (1.1 %) patients an eGFR <45 ml/min/1.73 m2. Model A detected 543 patients: 81 with eGFR <60 ml/min/1.73 m2 (missing 11) and all 11 with eGFR <45 ml/min/1.73 m2. Model B detected 420 patients: 70 (missing 22) with eGFR <60 ml/min/1.73 m2 and all 11 with eGFR <45 ml/min/1.73 m2. Associations were significant (p < 0.05).Conclusions: Model B resulted in the lowest superfluous eGFR measurements while detecting all patients with eGFR <45 ml/min/1.73 m2 and nearly all with eGFR <60 ml/min/1.73 m2.Key Points: • Less than 10% of patients undergoing contrast-enhanced CT have an eGFR of <60ml/min/1.73m 2 • Four risk factors can be used to detect pre-existent kidney disease • It is safe to reduce eGFR measurements using a four-risk-factor model. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the influence of scan duration on pharmacokinetic parameters and their performance in differentiating benign from malignant breast lesions. Methods: Dynamic breast imaging was performed on a 3.0-T MR system using a prototype CAIPIRINHA-Dixon-TWISTVIBE (CDT-VIBE) sequence with a temporal resolution of 11.9 s. Enrolled in the study were 53 women with 55 lesions (26 benign and 29 malignant). Pharmacokinetic parameters ( Ktrans, ve , kep and iAUC) were calculated for various scan durations from 1 to 7 min after injection of contrast medium using the Tofts model. Results: Ktrans, kep and ve calculated from the 1-min dataset were significantly different from those calculated from the other datasets. In benign lesions, Ktrans, kep and ve were significantly different only between 1 min and 2 min (corrected P > 0.05), but in malignant lesions there were significant differences for any of the comparisons up to 6 min vs. 7 min (corrected P > 0.05). There were no significant differences in AUCs for any of the parameters ( P > 0.05). Conclusions: In breast dynamic contrast-enhanced MRI the scan duration has a significant impact on pharmacokinetic parameters, but the diagnostic ability may not be significantly affected. A scan duration of 5 min after injection of contrast medium may be sufficient for calculation of Tofts model pharmacokinetic parameters. Key Points: • Scan duration of DCE-MRI breast imaging has a significant impact on pharmacokinetic parameters • A scan duration of less than 2 min results in spurious parameter estimates • The initial 2 min are important for both benign and malignant lesions • In malignant lesions the impact extends to 4 - 6 min • The differentiation ability of parameters may not be affected by scan duration [ABSTRACT FROM AUTHOR]

Objectives: To assess the contrast-enhanced ultrasound (CEUS) frequencies of centrifugal enhancement, spoke-wheel sign and central scar in focal nodular hyperplasia (FNH) as a function of lesion size. Methods: Ninety-four FNHs were retrospectively reviewed to assess their largest diameter and enhancement pattern, including centrifugal enhancement from one central artery, spoke-wheel sign, diffuse or centripetal enhancement, central scar and late-phase washout. Results: Mean FNH-lesion size was 3.7 ± 2.1 cm. Only 43.6 % of FNHs had centrifugal enhancement, with a spoke-wheel pattern (23.4 %) or without (20.2 %), while 56.4 % showed diffuse or centripetal enhancement. Centrifugal enhancement was observed in 73.9 % of FNHs ≤3.1 cm and 14.6 % of FNHs >3.1 cm ( P < 10). Size and frequency of centrifugal enhancement were negatively correlated ( r = -0.57, P < 10). The spoke-wheel pattern was also seen more frequently in smaller (37 %) than in larger FNHs (10.4 %) ( P < 10). Late-phase washout was described in 5.3 % of FNHs and was not size-dependent. Lesions with a central scar were larger than those without, respectively, 5.7 ± 1.7 and 3.6 ± 2.0 cm ( P = 0.012). Conclusions: Typical centrifugal enhancement yielding a confident FNH diagnosis is seen significantly more frequently when the lesion is ≤3.1 cm. Key Points: • CEUS yields confident diagnoses of FNHs ≤3.1 cm • The larger the FNH, the lower the diagnostic sensitivity of CEUS • Final diagnosis of FNHs >3.1 cm should be obtained with MRI not CEUS [ABSTRACT FROM AUTHOR]

Objective: To assess which risk factors can be used to reduce superfluous estimated glomerular filtration rate (eGFR) measurements before intravenous contrast medium administration. Methods: In consecutive patients, all decreased eGFR risk factors were assessed: diabetes mellitus (DM), history of urologic/nephrologic disease (HUND), nephrotoxic medication, cardiovascular disease, hypertension, age > 60 years, anaemia, malignancy and multiple myeloma/M. Waldenström. We studied four models: (1) all risk factors, (2) DM, HUND, hypertension, age > 60 years; (3) DM, HUND, cardiovascular disease, hypertension; (4) DM, HUND, age > 75 years and congestive heart failure. For each model, association with eGFR < 60 ml/min/1.73 m or eGFR < 45 ml/min/1.73 m was studied. Results: A total of 998 patients, mean age 59.94 years were included; 112 with eGFR < 60 ml/min/1.73 m and 30 with eGFR < 45 ml/min/1.73 m. Model 1 detected 816 patients: 108 with eGFR < 60 ml/min/1.73 m and all 30 with eGFR < 45 ml/min/1.73 m. Model 2 detected 745 patients: 108 with eGFR < 60 ml/min/1.73 m and all 30 with eGFR < 45 ml/min/1.73 m. Model 3 detected 622 patients: 100 with eGFR < 60 ml/min/1.73 m and all 30 with eGFR < 45 ml/min/1.73 m. Model 4 detected 440 patients: 86 with eGFR < 60 ml/min/1.73 m and all 30 with eGFR < 45 ml/min/1.73 m. Associations were significant ( p < 0.001). Conclusion: Model 4 is most effective, resulting in the lowest proportion of superfluous eGFR measurements while detecting all patients with eGFR < 45 ml/min/1.73 m and most with eGFR < 60 ml/min/1.73 m. Key Points: • A major risk factor for contrast-induced nephropathy (CIN) is kidney disease. • Risk factors are used to identify patients with pre-existent kidney disease. • Evidence for risk factors to identify patients with kidney disease is limited. • The number of eGFR measurements to detect kidney disease can be reduced. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of a newly developed connecting tube, which generates a spiral flow of saline, on aortic and hepatic contrast enhancement during hepatic-arterial phase (HAP) and portal venous phase (PVP) computed tomography (CT). Methods: Eighty patients were randomly assigned to one of two protocols: with a new or a conventional tube. The contrast material (600 mgI/kg) was delivered over 30 s; this was followed by the administration of 25 ml saline solution delivered at the same injection rate as the contrast material. Unenhanced and contrast-enhanced CT images of the upper abdomen were obtained. We calculated the changes in the CT number (∆HU) for the aorta during HAP and PVP, and for the liver during PVP. We compared ∆HU between protocols. Results: The mean ∆HU for the abdominal aorta during HAP was significantly higher with the new tube protocol than with the conventional tube protocol (322 ± 53 vs. 290 ± 53, P < 0.01). There were no significant differences in the mean ∆HU for the abdominal aorta and liver during PVP between the two protocols ( P > 0.05). Conclusion: The new connecting tube increased the effect of a saline chaser and significantly improved aortic enhancement during HAP. Key Points: • Optimal administration of intravenous contrast material is essential for optimal CT quality. • A new connecting tube can generate spiral flow, which improves intravenous administration. • The new connecting tube improved aortic contrast enhancement during the hepatic-arterial phase. • The new connecting tube increased the effect of a saline chaser. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the effect of contrast medium dose adjustment for body surface area (BSA) compared with a fixed-dose protocol in combined positron emission tomography (PET) and computed tomography (CT) (PET/CT). Methods: One hundred and twenty patients were prospectively included for F-2-deoxy-fluor-glucose (F-FDG)-PET/CT consisting of a non-enhanced and a venous contrast-enhanced CT, both used for PET attenuation correction. The first 60 consecutive patients received a fixed 148-ml contrast medium dose. The second 60 patients received a dose that was based on their calculated BSA. Mean and maximum standardised FDG uptake (SUVmean and SUVmax) and contrast enhancement (HU) were measured at multiple anatomical sites and PET reconstructions were evaluated visually for image quality. Results: A decrease in the variance of contrast enhancement in the BSA group compared with the fixed-dose group was seen at all anatomical sites. Comparison of tracer uptake SUVmean and SUVmax between the fixed and the BSA group revealed no significant differences at all anatomical sites (all P > 0.05). Comparison of the overall image quality scores between the fixed and the BSA group showed no significant difference ( P = 0.753). Conclusions: BSA adjustment results in increased interpatient homogeneity of contrast enhancement without affecting PET values. In combined PET/CT, a BSA adjusted contrast medium protocol should be used preferably. Key Points: • Intravenous contrast medium is essential for many applications of PET/CT • Body surface area adjustment of contrast medium helps standardise contrast enhancement • Underdosing or overdosing of contrast medium will be reduced • PET image quality is not influenced • BSA adjusted contrast medium protocol should be used preferably in combined PET/CT [ABSTRACT FROM AUTHOR]

Magnetic resonance angiography (MRA) with the blood pool agent gadofosveset trisodium (Vasovist®, Bayer Schering Pharma AG, Berlin, Germany) is a promising new, non-invasive imaging modality for the detection and characterisation of peripheral vascular disease. It offers for the first time the ability to expand the imaging window far beyond the first arterial bolus passage and allows for the acquisition of very high spatial resolution data during the so-called steady state (blood pool or equilibrium phase). Furthermore, information about the venous system is available with a blood pool agent without the need of multiple injections. In this article imaging strategies for peripheral MRA with gadofosveset trisodium are discussed. We describe the advantages of high resolution steady state imaging and provide recent clinical results of this new imaging tool which shows improved diagnostic accuracy of steady-state imaging compared to first-pass imaging and DSA as the reference standard and impact on patient management. [ABSTRACT FROM AUTHOR]

The purpose of this work was to test the feasibility of an MR examination protocol for the comprehensive assessment of renal morphology, excretion and split renal function using a navigator-gated TurboFLASH sequence. A navigator-gated T1-weighted single-slice TurboFLASH sequence suitable for dynamic MR urography and nephrography was implemented. A protocol was developed allowing for assessment of urinary excretion and split renal function by recording the renal clearance of a gadolinium (Gd) diethylene-triamine-pentacetic-acid (DTPA) bolus. Ten patients aged between 14 months and 14 years (mean age 4.8+/-4.6 years) were evaluated with the following indications: pelvicalyceal dilatation (n=4), follow-up after pyeloplasty (n=1), duplex systems (n=3), large renal cyst (n=1), and renal insufficiency (n=1). Dynamic MR urography and MR split renal function were compared to MAG3 scintigraphy. Evaluation of morphology, excretion and function required 50-60 minutes examination time, plus 10 minutes for post-processing. The TurboFLASH sequence yielded image acquisition at nearly identical diaphragm positions allowing for accurate region-of-interest evaluation within the renal parenchyma and the urinary passage. Static and dynamic MR urography showed the morphology of the urinary tract and excretion with sufficient diagnostic imaging quality, and the results were in diagnostic compliance with scintigraphy. MRI and scintigraphy yielded similar results for split renal function with a correlation coefficient of R=0.968 determined by linear regression. Our conclusions were that the method is robust, easy to perform on a clinical 1.5 T MRI system, rapid to evaluate and post-process and, therefore, easy to incorporate into clinical routine. Compared to scintigraphy, the higher spatial resolution of the MR examination provides additional important information improving the management of the pediatric patients without the application of radioactive tracers. [ABSTRACT FROM AUTHOR]

This work evaluates carbon dioxide as a contrast medium for magnetic resonance imaging of the stomach and small bowel. Twelve healthy volunteers underwent rapid magnetic resonance imaging after oral administration of a carbon dioxide generating agent using a combination of breath-hold and interactive fluoroscopic imaging during breathing. Diagnostic-quality images were obtained in 100% of cases for the stomach and in 92, 75, 67 and 42% of cases for the duodenal segments 1-4, respectively. Visualisation of the jejunum and ileum proved unacceptable for clinical use and anti-peristaltic agents did not significantly influence the results. Further development of fast imaging and magnetic resonance interactive fluoroscopic methods may allow the use of carbon dioxide as a contrast medium for clinical imaging of the stomach and duodenum. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the potential of intramyocardially injected Gd-DTPA solution as a marker for distribution of intramyocardially delivered therapeutic solutions. The effects of concentration and volume of the extracellular MR contrast medium Gd-DTPA on signal intensity and spatial extent of enhancement was determined after intramyocardial delivery. In anesthetized pigs (n=11), mixtures of Gd-DTPA (0.15, 0.1 and 0.05 mmol/ml) and Evan's blue tissue dye (3%) were injected into the wall of the left ventricle. In each pig 1 ml of 0.15 mmol/ml, 2 ml of 0.1 ml and 3 ml of 0.05 mmol/ml Gd-DTPA were injected remote from each other. Arterial blood pressure, heart rate and ECG were monitored throughout the procedure. Five minutes after injections were performed, the pigs were killed and the hearts excised. T1-weighted spin-echo MR images were acquired to measure regional signal intensity (SI) and extent of the enhanced regions. The hearts were sliced and mass of blue stained regions was determined and compared with mass of enhanced areas on MRI. Gd-DTPA significantly (p<0.001) increased regional SI compared with remote myocardium in a concentration dependent fashion (109 +/- 4% at 0.05 mmol/ml, 202 +/- 7% at 0.1, and 327 +/- 6% at 0.15) while the mass of enhanced region was 0.6 +/- 0.1 g after injection of 1 ml, 1.4 +/- 0.2 g after 2 ml and 2.3 +/- 0.3 g after 3 ml (p<0.001). Regression and Bland-Altman analysis revealed that there was close correlation and agreement between MRI and histomorphometry (r=0.98, p<0.001). Magnitude and spatial extent of enhancement depend on concentration and volume of injected contrast medium. Intramyocardial injection of extracellular MR contrast media may be useful as a marker for the extent of distribution of intramyocardially delivered therapeutic solutions. [ABSTRACT FROM AUTHOR]

The aim of this study was to report our experience with transperineal ultrasound in studying the urethra, as a complementary technique to contrast-enhanced voiding urosonography (VUS). The VUS was performed in 350 patients (244 males, 106 females) less than 4 years of age, and complemented with perineal US. Ultrasound of the kidneys and bladder was obtained before and during bladder filling and post-voiding. The urethra and the neck of the bladder were evaluated sagittally by transperineal ultrasound (5-7.5 MHz) before, during, and after voiding. Only cases of posterior urethral valves diagnosed at VUS were followed by voiding cystourethrography (VCUG), which was performed on a different day. A satisfactory evaluation of the urethra was obtained in 332 cases (94.86%): (a). normal urethra ( n=328); and (b). posterior urethral valves ( n=4). In the latter 4 cases there was concordance between results at VUS and VCUG. Eighteen cases (5.14%) were excluded from the study because the quality of the examination was suboptimal. Transperineal US offers an initial imaging modality for studying urethral pathology and thus may complement VUS. [ABSTRACT FROM AUTHOR]

Macromolecular contrast media (MMCM) encompass a new class of diagnostic drugs that can be applied with dynamic MRI to extract both physiologic and morphologic information in breast lesions. Kinetic analysis of dynamic MMCM-enhanced MR data in breast tumor patients provides useful estimates of tumor blood volume and microvascular permeability, typically increased in cancer. These tumor characteristics can be applied to differentiate benign from malignant lesions, to define the angiogenesis status of cancers, and to monitor tumor response to therapy. The most immediate challenge to the development of MMCM-enhanced mammography is the identification of those candidate compounds that demonstrate the requisite long intravascular distribution and have the high tolerance necessary for clinical use. Potential mammographic applications and limitations of various MMCM, defined by either experimental animal testing or clinical testing in patients, are reviewed in this article. [ABSTRACT FROM AUTHOR]

The detection and characterization of pancreatic tumors as well as the reliable staging of pancreatic cancer are important tasks for radiologic evaluation. Contrast-enhanced helical CT has been the standard modality for pancreatic imaging in many institutions, but MR imaging has gained a considerable role in the evaluation of patients with equivocal CT findings. Recently, the first organ-specific MR contrast agent targeted to the liver and pancreas, mangafodipir trisodium, has been registered in the European Union (EU) for use in MR imaging of the pancreas. This paper reviews technical considerations and characteristic imaging findings of mangafodipir-enhanced MR imaging in the assessment of focal pancreatic lesions. Contrast-enhanced MRI has proven to be very helpful in the detection of small tumors or the identification of tumor-simulating lesions in patients with equivocal CT findings. Mangafodopir may improve the staging of pancreatic cancer by increasing the sensitivity of MRI in the detection of liver metastases. This review summarizes the potential of contrast-enhanced MRI and the limitations compared with contrast-enhanced helical CT. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine hepatic and vascular enhancement, clinical tolerance, and iconographic quality of Iobitridol (300 mg/ml) at dual-phase helical CT and to compare it with Iohexol (300 mg/ml). One hundred forty-six patients were randomly divided into two groups. Each group received 120 ml of Iohexol (group A) or Iobitridol (group B). Mean enhancement of liver, aorta and portal vein was obtained at the arterial phase and at the portal-venous phase. Overall image quality was assessed by two independent blinded investigators. Adverse reactions were recorded. There were no significant differences in demographic characteristics and distribution of patient intrinsic parameters between the two groups, except for blood pressure but without statistical correlation between the difference in blood pressure and the impact on enhancement measurements. There was no significant difference in clinical tolerance and image quality. Mean liver as well as aortic and portal vein enhancement measurements did not show any significant difference. Iobitridol compares favorably with Iohexol. Both products have similar safety, tolerance, and efficacy. Both contrast media have equivalent blood pool concentration and interstitial compartment diffusion. [ABSTRACT FROM AUTHOR]

The authors report a case of successful detection of pulmonary embolism using gadolinium-enhanced spiral CT (Gadodiamide, 0.4 mmol/kg, 2 ml/s, delay 18 s) in a 77-year-old woman, with previous allergy to iodinated contrast medium, and renal failure, who presented with pulmonary arterial hypertension. Doppler ultrasound of the lower limbs was first performed and revealed a deep venous thrombosis of the right lower limb. To establish if venous thrombosis was the cause of pulmonary hypertension and to confirm that pulmonary endarterectomy was not indicated in this situation, several imaging modalities were performed. Lung scintigraphy and MRI were non-diagnostic. Gadolinium-enhanced spiral CT demonstrated a large thrombus located proximally and in a segmental artery of the right lower lobe. This case illustrates the potential usefulness of gadolinium as alternative contrast agent with spiral CT to diagnose pulmonary embolism and elucidate the cause of pulmonary arterial hypertension in a patient with some contraindications for iodinated contrast medium injection. [ABSTRACT FROM AUTHOR]

Metastatic involvement of axillary lymph nodes is one of the most important prognostic variables in breast cancer. The aim of our work was to study the value of dynamic contrast-enhanced MR imaging in revealing axillary lymph node metastases from breast cancer. A total of 65 patients with invasive breast cancer treated with axillary lymph node dissection were preoperatively evaluated by MRI. T1-weighted dynamic contrast-enhanced 3D images were acquired using a coil covering the breast and the axilla. The dynamic contrast enhancement, size, and morphology of the axillary lymph nodes were registered. Histopathological examination revealed axillary lymph node metastases in 24 patients. When using a signal intensity increase in the lymph nodes of >100% during the first postcontrast image as a threshold for malignancy, 57 of 65 patients were correctly classified (sensitivity 83%, specificity 90%, accuracy 88%). These results were not improved when lymph node size and morphology were used as additional criteria. Axillary lymph nodes can be evaluated as a part of an MR-mammography study without substantial increase in examination time, and provide the surgeon with knowledge about the localization of possible metastatic lymph nodes. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the efficacy of contrast-medium (CM)-ehanced MR imaging of operated pituitary macroadenomas with reduced dose of gadopentetate dimeglumine. In a prospective study 18 patients were examined with coronal T1-weighted MR imaging prior to and following intravenous CM injections. Two sets of contrast-enhanced coronal images were obtained in each patient; the first set after 50% of the recommended dose of 0.1 mmol/kg body weight (b.w.) had been administered, and the second set immediately after additional CM had been given to make up a total dose of 0.1 mmol/kg b.w. The images were evaluated by three neuroradiologists. The SIPAP classification system was used to evaluate tumour extension, whereas tumour margin conspicuity was scored using an arbitrary scale of 1-5 (1 = indistinct, 5 = well defined). Signal intensity measurements obtained from the most enhancing part of the adenomas demonstrated increased enhancement with increased CM dose. Tumour delineation scores were significantly better on the reduced- and full-dose images than on pre-CM injection images, but, with one exception, tumour extension was identified as the same on all imaging sequences. Postoperative MR imaging of large macroadenoma residues can routinely be performed without intravenous CM. When CM is indicated a reduced dose of gadopentetate dimeglumine should provide sufficient diagnostic information. [ABSTRACT FROM AUTHOR]

A non-ionic, monomeric, low-osmolar contrast medium, iopentol (Imagopaque®, Nycomed Imaging AS, Oslo, Norway) has been compared with iohexol (Omnipaque®, Nycomed Imaging AS, Oslo, Norway) in a double-blind, randomized, parallel-group trial in children. The aims of the study were to compare the safety and radiographic efficacy of iopentol 350 mg I/ml versus those of iohexol 350 mg I/ml in pediatric cardioangiography. Seventy-three children, of whom 35 received iopentol and 38 iohexol, were included in the evaluation. The quality of overall diagnostic information was excellent or adequate in all patients. There were no statistically significant differences between numbers of patients reporting adverse events nor number of patients reporting discomfort in the two groups. Three patients in the iopentol group and two patients in the iohexol group reported adverse events. Heat sensation was reported by 4 patients in the iopentol group and 5 patients in the iohexol group. Following injection of contrast medium, there were no differences between the groups regarding ECG, heart rate and systolic blood pressure at the site of injection. Iopentol was demonstrated to be as effective, safe and well tolerated as iohexol in pediatric cardioangiography. [ABSTRACT FROM AUTHOR]

Iopentol (Imagopaque); 300 mg I/ml was compared with ioxaglate (Hexabrix; 320 mg I/ml in 89 patients (45 and 44 patients, mean age 8.5 and 7.9 years in the contrast groups, respectively), in paediatric intravenous CT contrast enhancement. The dose injected was 2 ml/kg b.w. with an upper limit of 100 ml. There was a total of 18 patients who reported adverse events other than sensations of heat or cold, 6 (13%) in the iopentol group and 12 (27%) in the ioxaglate group. Two patients (4%) in the iopentol group reported possible contrast-related events as described above, whereas the number was 8 (18%) in the ioxaglate group. There was no statistically significant difference between the two groups regarding adverse events, blood pressure, nor heart rate changes after injection. The overall quality of CT enhancement was excellent or sufficient in 96 and 93% of the cases in the iopentol and ioxaglate groups, respectively. Iopentol was shown to be a safe and effective contrast medium in examinations of children. [ABSTRACT FROM AUTHOR]

In order to evaluate the safety and efficacy of a high-dose gadodiamide injection a phase-III trial was conducted using a dose of 0.3 mmol Gd/kg bw in patients with known or suspected tumors in the head and neck region. A total of 90 in- and outpatients referred to MR examination for tumor in the head and neck area were included. Precontrast images consisted of T- and T-weighted sequences. A FATSAT sequence was also applied. After i. v. contrast administration T-weighted scans were obtained. Efficacy was evaluated by means of a comparison of the pre- and postcontrast images. Postcontrast images gave more diagnostic information compared with precontrast images, which facilitated diagnosis in all patients. In 8 patients T-weighted postcontrast images revealed abnormal structures not seen on precontrast images and no lesion was obscured by the contrast medium. Gadodiamide injection at a dose of 0.3 mmol Gd/kg bw was judged as safe and effective for the examination of tumors in the head and neck region. Use of the contrast medium increased the diagnostic information in the images and increased the confidence in making the diagnosis. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the utility of a dynamic contrast enhanced FLASH-2D sequence for differential diagnosis of tumours in head and neck in 93 patients. Initially, the localization of the lesion and the selection of four representative slices for the dynamic study were obtained by a T2-weighted spin-echo sequence (TR 2000-3000 ms; TE 25/90 ms). After IV bolus injection of the contrast agent 10 images were acquired during a period of 3 min by a FLASH-2D sequence (TR 60 ms; TE 6 ms; flip angle 40° matrix 256 × 256; one acquisition). The percentage signal intensity (SI) increase (r) and the slope (S) of the curve were calculated on the basis of the SI time curve of the pathological lesion and of muscle. Inflammatory processes could be differentiated from malignant or benign tumours by means of a higher contrast enhancement. The time of the maximum SI was not specific for the different lesions. In comparison with muscle the maximum SI change was achieved earlier in a pathological process. [ABSTRACT FROM AUTHOR]

Nonionic contrast media (NICM) used in radiology exhibit weaker anticoagulant properties than ionic media. This study was intended to evaluate the effect of iopromide NICM upon the platelet aggregation and their membrane structure (investigated by electron paramagnetic resonance method with a spin label). Blood was collected directly from the left ventricle during coronary angiography prior to and following the application of the contrast medium. These results were compared with in vitro examinations. Based on the spectral curves parameters that reflect conformational changes in membrane proteins were determined. The iopromide-induced decrease in platelet aggregation examined in vitro with adenosine diphosphate (ADP), collagen and ristocetine was statistically significant. In vitro platelet membrane structure was modified significantly with regard to both protein conformation and the accessibility of sulfhydryl (- SH) and amino (- NH) groups. In ex vivo studies the changes in platelet aggregation was only observed with ADP, whereas in the membrane-structure modifications were only noted regarding accessibility of - SH and - NH groups. We conclude that iopromide-induced platelet aggregation changes are most probably due to their membrane-structure modifications, whereas the less-pronounced contrast effect ex vivo is due to its rapid dilution in the inflowing blood. The results confirm weak antiplatelet and anticoagulant influence of NICM in vivo. [ABSTRACT FROM AUTHOR]

A double-blind, randomized, parallel study was conducted to evaluate the safety and diagnostic utility of gadodiamide injection (a nonionic chelate of gadolinium and diethylenetriamine pentaacetic acid bis-(methylamide) [Gd-DTPA-BMA]) when administered IV for MRI of the central nervous system (CNS) at doses of 0.1 mmol/kg body weight (b. w.) or 0.3 mmol/kg b. w. A total of 24 patients received the lower dose and 23 the higher dose. Gadodiamide injection was administered to patients referred for MRI due to known or suspected CNS lesions. No clinically significant difference in blood parameters or efficacy was found between the two groups. The number of patients with adverse events other than discomfort was higher in the 0.3 group compared with the 0.1 group. In the 0.1 group, none of the 24 patients experienced any adverse events other than discomfort, and in the 0.3 group, 5 of 23 patients (21.7%) experienced a total of five adverse events other than discomfort. All adverse events were of mild or moderate intensity. Postinjection MR scans provided new information that affected patient management in the case of 6 patients in the 0.1 group and 9 in the 0.3 group. [ABSTRACT FROM AUTHOR]

CT of the entire clean colon after a tap water enema with intravenous injection of contrast medium was performed in 20 patiens with a diagnosis of caecal and ascending colonic lesions at barium enema studies or colonoscopy. Histological proof was obtained by endoscopy or at surgery in all cases. Using this 'water technique' we were able to detect the wall abnormalities and describe their CT features in relation to the histological findings. We found that asymmetric thickening of the bowel wall, an irregular and lobulated inner and outer contour and/or a focal soft tissue mass usually exceeding 2 cm from the luminal to serosal surface were very helpful findings for a malignant lesion but not the hallmark of malignancy. The CT appearance of the extraluminal part of the lesion was most helpful in differentiating between benign and malignant lesions. [ABSTRACT FROM AUTHOR]