The optimal contrast media policy in CT of the liver. Part II: Clinical protocols.

The advent of multidetector computed tomography (MDCT) revolutionized abdominal imaging. In particular, the definitive assessment of CT injection protocols, for the evaluation of the liver parenchyma, is still a critical issue for radiologists. Over the last years, this feature encouraged several authors to address their efforts to find the most accurate delay between the contrast medium injection and the effective scan-start, for the identification and characterization of liver lesions. Technological developments of the present century such as number of slices, submillimetric collimation, and the use of multiple dynamic post-contrast phases per single examination, may all contribute to increase the radiation exposure of single patients. The aim of this review is to propose liver imaging protocols, taking into consideration different clinical needs such as patients with chronic liver disease, healthy patients with focal liver lesion, and oncological patients to minimize radiation exposure. Finally, two recent innovations in MDCT which illustrate the potential application of multi-energy computed tomography (MECT) and perfusion computed tomography (CTp) when evaluating liver parenchyma will be discussed in a short closing paragraph.

The optimal contrast media policy in CT of the liver. Part I: Technical notes.

Latest developments of multidetector computed tomography (MDCT), which is today considered a real volumetric technique, have revolutionized abdominal imaging. Technological improvements such as higher spatial resolution, larger volume coverage and higher temporal resolution, have reduced scan times allowing CT studies of the abdomen within a single breath-hold. Furthermore, the increased number of slices, the submillimetric collimation, and the use of multiple dynamic post-contrast phases per single examination, may all contribute to increase the radiation exposure of single patients. The aim of this review is to discuss different parameters affecting contrast media enhancement, as vascular enhancement, parenchymal enhancement and timing, in order to minimize the amount of contrast medium injected and the radiation exposure.

Anatomic variations of the hepatic arteries in 250 patients studied with 64-row CT angiography.

The aim of our study was to determine the frequency of different hepatic arterial variants identified on abdominal CT angiography (CTA) with a 64-row CT system and a high resolution protocol. A total of 250 consecutive abdominal CTAs performed on a 64-row CT system were evaluated. Two radiologists in consensus analyzed arterial phase images; the anatomical findings were grouped according to Michels' classification. An anomalous arterial pattern was observed in 34% of the cases. The most common anomaly was Michels type III (9.2%), followed by types II and V (5.2%), type VI (4.0%), types IV, VII, and IX (2.0%), and type VIII (0.6%). No cases of type X were detected. Unclassified variations were observed in 3.3% of the cases. The new generation of 64-row MDCT allows optimal visualization of splanchnic vascular anomalies with a minimally invasive examination. This visualization is extended to those vessels with a small caliber and slow flow resulting in difficult recognition by classic angiographic studies. The knowledge of anomalous arterial patterns could be very useful in the preoperative planning of surgical and interventional liver procedures.

High concentration (400 mgI/mL) versus low concentration (320 mgI/mL) iodinated contrast media in multi detector computed tomography of the liver: a randomized, single centre, non-inferiority study.

OBJECTIVES: To compare vascular and parenchymal contrast enhancement in multidetector computed tomography of the liver using two contrast media with different iodine concentration (Iodixanol 320 mgI/mL and Iomeprol 400 mgI/mL) and similar viscosity, using fixed total iodine volume (40 gI) and iodine delivery rate (1.6 gI/s). METHODS: 110 patients were prospectively randomized into two groups. Group A received 125 mL of Iodixanol 320 and group B 100 mL of Iomeprol 400. Attenuation values were measured at the level of the aorta, portal vein and liver parenchyma on unenhanced, arterial, portal and equilibrium phases. A non inferiority test was performed on the differences between the two groups. An independent reader evaluated image quality. RESULTS: The equivalence of the two CM was demonstrated in all measurements. Higher, but not statistically significant, attenuation values were obtained with Iomeprol 400 in the aorta during the arterial phase (305.3 HU versus 288.4 HU; P=0.32) and with Iodixanol 320 in the liver parenchyma, during both portal (59.8 HU versus 65.5 HU; P=0.78) and equilibrium (40.4 HU versus 41.8 HU; P=0.55) phases. CONCLUSIONS: Iodixanol 320 and Iomeprol 400 injected at the same iodine delivery rate (1.6 gI/s) and total iodine load (40 gI) did not provide statistically significant differences in liver parenchymal and vascular contrast enhancement.

Current status of MR imaging in the evaluation of IBD in a pediatric population of patients.

Diagnosis and follow-up of inflammatory bowel disease (IBD) in children represent a challenging issue for pediatricians. Nowadays MR studies of the bowel represent a valid diagnostic tool especially in the diagnosis and follow-up of ileal and perianal Crohn's disease in children as well as in adults. The lack of ionizing radiation of MRI enhances the interest of clinicians with respect to CT studies of the bowel in children. Thanks to recent technical development in terms of fast MR images acquisition a reasonable image quality can be easily achieved in scholar-age children. A majority of authors prefer MR-enterography approach in children with respect to the more invasive MR-enteroclysis in the assessment of ileal Crohn's disease. Using rigorous technique of MR-enterography represents a feasible and accurate test in the diagnosis of ileal Crohn's disease. Less experience is collected on MR-colonography in pediatric IBD while MRI of the pelvis represents the most accurate non-invasive diagnostic test in the assessment of perianal Crohn's disease in children as well as in adults.