Iopentol (Imagopaque 350) compared with diatrizoate (Urografin 370) in cerebral CT. A clinical trial assessing immediate and late (7 days) adverse events and diagnostic information (visualization quality and Hounsfield unit measurements)

PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning

The positron emission tomography in combination with CT in hybrid, cross-modality imaging systems (PET/CT) gains more and more importance as a part of the treatment-planning procedure in radiotherapy. Positron emission tomography (PET), as a integral part of nuclear medicine imaging and non-invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy. By the choice of the PET-Tracer, a variety of different metabolic processes can be visualized. First and foremost, this is the glucose metabolism of a tissue as well as for instance hypoxia or cell proliferation. This paper comprises the system characteristics of hybrid PET/CT systems. Acquisition and processing protocols are described in general and modifications to cope with the special needs in radiooncology. This starts with the different position of the patient on a special table top, continues with the use of the same fixation material as used for positioning of the patient in radiooncology while simulation and irradiation and leads to special processing protocols that include the delineation of the volumes that are subject to treatment planning and irradiation (PTV, GTV, CTV, etc.). General CT acquisition and processing parameters as well as the use of contrast enhancement of the CT are described. The possible risks and pitfalls the investigator could face during the hybrid-imaging procedure are explained and listed. The interdisciplinary use of different imaging modalities implies a increase of the volume of data created. These data need to be stored and communicated fast, safe and correct. Therefore, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and computed tomography (CT) are used to communicate the actual image data created by the modalities. Care must be taken for data security, especially when transferring data across the (network-) borders of different hospitals. Overall, the most important precondition for successful integration of functional imaging in RT treatment planning is the goal orientated as well as close and thorough communication between nuclear medicine and radiotherapy departments on all levels of interaction (personnel, imaging protocols, GTV delineation, and selection of the data transfer method).

Delayed adverse reaction to contrast-enhanced CT: a prospective single-center study comparison to control group without enhancement

PURPOSE

To prospectively assess the incidence of delayed adverse reactions (DARs) in patients undergoing contrast material-enhanced computed tomography (CT) with the low osmolar nonionic contrast agent iohexol and compare with the incidence of DARs in patients undergoing unenhanced CT as control subjects.

MATERIALS AND METHODS

Institutional review board approval and informed written consent for this prospective study were obtained. The study was HIPAA compliant. Patients undergoing CT for routine indications were enrolled from a random next-available scheduling template by an on-site clinical trials monitor. All subjects received a questionnaire asking them to indicate any DAR occurring later than 1 hour after their examination. Sixteen manifestations were listed and included rash, skin redness, skin swelling, nausea, vomiting, and dizziness, among others. To ensure maximal surveillance, a clinical trials coordinator initiated direct telephone contact for further assessment. Patients suspected of having moderately severe cutaneous reactions were invited to return for a complete dermatologic clinical assessment including skin biopsy, if indicated. Statistical analysis was performed by using a two-sided Wilcoxon-Mann-Whitney test, a logistic regression utilizing a chi(2) test to adjust for sex and age, and a two-sided Fisher exact test.

RESULTS

A total of 539 patients (258 receiving iohexol and 281 not receiving contrast material) were enrolled. DARs were observed in 37 (14.3%) of 258 subjects receiving iohexol and in seven (2.5%) of 281 subjects in the control group (P < .0001, chi(2) test) after adjusting for sex and age. Specific manifestations of DARs that were significantly more frequent at contrast-enhanced CT were skin rash (P = .0311), skin redness (P = .0055), skin swelling (P = .0117), and headache (P = .0246). DARs involving the skin included generalized rashes of the face, neck, chest, back, and extremities and were often associated with swelling, erythema, and pruritus.

CONCLUSION

This study substantiates a frequent occurrence of DARs at contrast-enhanced CT compared with that in control subjects. Continued growth in the use of contrast-enhanced CT suggests a need for greater awareness and attention to prevention and management.

Comparison of two contrast materials with different iodine concentrations in enhancing the density of the the aorta, portal vein and liver at multi-detector row CT: a randomized study

This work investigates differences in contrast enhancement of the aorta, portal vein and liver by two different concentrations of contrast materials using an automatic bolus tracking technique. Seventy patients were assigned randomly into one of two groups. Contrast materials with iodine concentrations of 300 and 370 mg/ml were administered to patients in groups A and B, respectively. The total iodine load (600 mg/kg) and injection time (30 s) were identical. Differences in the increase of the Hounsfield unit of the aorta, portal vein and liver between the two groups were examined by t-test. There were no significant differences between the two groups in any of the contrast enhancements of the aorta, portal vein and liver parenchyma at all phases, except for enhancement of the portal vein at the late arterial phase. Females showed better contrast enhancement of the aorta and portal vein than males. With the same iodine dose and injection time, the concentration of contrast materials did not seem to influence the efficacy of contrast enhancement of the aorta, portal vein and liver, except for the portal vein at the late arterial phase. Planning of protocols for contrast media injection may be made irrespective of the iodine concentrations.