The prospective evaluation of Gd-DTPA in 225 consecutive cranial cases: adverse reactions and diagnostic value

Exclusion of a brain lesion: is intravenous contrast administration required after normal precontrast magnetic resonance imaging?

Background

No evidence‐based guidelines are available for the administration of gadolinium‐based contrast media to veterinary patients.

Objective

To investigate whether administration of intravenous (IV) contrast media alters the likelihood of identifying a brain lesion in dogs and cats.

Animals

Four hundred and eighty‐seven client‐owned animals referred for investigation of intracranial disease.

Methods

Two reviewers retrospectively analyzed precontrast transverse and sagittal T1‐weighted (T1W), T2‐weighted, and fluid‐attenuated inversion recovery low‐field MRI sequences from each patient for the presence of a clinically relevant brain lesion. All sequences subsequently were reviewed in the same manner with additional access to postcontrast T1W images.

Results

Of the 487 precontrast MRI studies, 312 were judged to be normal by 1 or both reviewers. Of these 312 studies, a previously undetected lesion was identified in only 6 cases (1.9%) based on changes observed on postcontrast sequences. Final diagnoses included meningoencephalitis of unknown origin (n = 1), feline infectious peritonitis (n = 1), and neoplasia (n = 2). All 4 of these cases had persistent neurological deficits suggestive of an underlying brain lesion. Contrast enhancement observed in the 2 other cases was considered falsely positive based on the results of further investigations.

Conclusions and Clinical Importance

In patients with normal neurological examination and normal precontrast MRI, the subsequent administration of IV gadolinium‐based contrast media is highly unlikely to disclose a previously unidentified lesion, calling into question the routine administration of contrast media to these patients. However, administration still should be considered in animals with persistent neurological deficits suggestive of an underlying inflammatory or neoplastic brain lesion.

Quantification of dispersion of Gd-DTPA from the initial area of enhancement into the peritumoral zone of edema in brain tumors

To evaluate Gd-DTPA contrast enhancement of brain tumors over time and to describe the dispersion of contrast into the zone of peritumoral edema. We performed MR imaging with a dose of 0.4 mmol Gd-DTPA/kg on eleven patients diagnosed with 5 different supratentorial tumors. MR imaging was done at five intervals between 5 min and 6 h. The change in zone of enhancement was measured for each time point, and a linear measurement was made of the furthest dispersion of contrast from the original volume of enhancement. An increase in the zone of enhancement over time was seen for all tumors; the average increase in volume of contrast was 14.76 +/- 3.35 cm(3) (mean +/- standard deviation). The largest changes in the zone of contrast enhancement, 18.6 +/- 4.63 cm(3), were seen in glioblastoma multiforme. The expansion of contrast enhancement assumed the morphology of the surrounding edema. The dispersion of Gd-DTPA over time into the zone of peritumoral edema is a potential source of error in clinical settings when there is a delay between Gd-DTPA injection and scanning.

Neuroimaging contrast agents in ophthalmology

Magnetic resonance (MR) imaging and computed tomography (CT) are routinely performed with the use of contrast materials in the diagnosis of neuro-ophthalmologic disease. Iodinated agents are commonly used in CT scanning and femoral contrast arteriography, and gadolinium is used in MR imaging. While contrast materials contribute greatly to diagnostic accuracy, they may also be responsible for adverse effects, ranging in severity from mild discomfort to death. The most frequent and severe side effects are associated with ionic iodinated contrast agents, while the rate of adverse reactions is less with use of nonionic iodinated contrast agents. Side effects and adverse reactions to gadolinium are uncommon, but they do occur. In neuro-ophthalmologic diagnosis, MR imaging is generally preferred over CT scanning, partly because of its greater ability to delineate soft tissue intracranial structures, but also because of the relative safety of gadolinium as a contrast agent. Properties of contrast agents are discussed in the context of specific imaging techniques and tissues investigated. Types and severity of adverse effects as well as risk factors for incurring such effects are summarized.

Enhanced magnetic resonance imaging evaluation for spread of cervical carcinoma

OBJECTIVES

Clinical diagnosis of cervical carcinoma fails to detect the location and extent of tumor invasion to cervical stroma and parametria. This study attempted to assess the accuracy of gadopentetate dimeglumine (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) in the evaluation for the extent of cervical carcinoma.

METHODS

A total of 41 patients with primary untreated cervical carcinoma underwent MRI throughout the staging evaluations before surgical treatment.

RESULTS

Without Gd-DPTA, T1-weighted images were less effective than T2-weighted images for MRI of pelvic organs. Gd-DTPA-enhanced T1-weighted images provided information similar to those of T2-weighted appearances, and distinguished the normal parametrium or vaginal wall from malignant invaded lesions more clearly.

CONCLUSIONS

The enhancement with Gd-DTPA may increase the ability of MRI to provide a positive spread/metastasis staging.

High-dose gadoteridol in MR imaging of intracranial neoplasms

Twelve patients with a high suspicion of brain metastases by previous clinical or radiologic examinations were studied in a phase III investigation with magnetic resonance (MR) imaging at 1.5 T after a bolus intravenous injection of 0.1 mmol/kg gadoteridol followed at 30 minutes by a second bolus injection of 0.2 mmol/kg gadoteridol. All lesions were best demonstrated (showed greatest enhancement) at the 0.3-mmol/kg (cumulative) dose, with image analysis confirming signal intensity enhancement in the majority of cases after the second gadoteridol injection. More lesions were detected with the 0.3-mmol/kg dose than with the 0.1-mmol/kg dose, and more lesions were detected with the 0.1-mmol/kg dose than on precontrast images. In this limited clinical trial, high-dose gadoteridol injection (0.3-mmol/kg cumulative dose) provided improved lesion detection on MR images specifically in intracranial metastatic disease.

Magnetic resonance imaging in monitoring the treatment of multiple sclerosis: concerted action guidelines

Serial gadolinium enhanced MRI of the brain detects much clinically silent disease activity in early relapsing-remitting and secondary progressive multiple sclerosis (MS), and thus has an important role in monitoring the effects of therapy. Based on the proceedings of a recent Commission of the European Communities (CEC) workshop and a review of the literature, guidelines are presented for using MRI to monitor treatment trials in MS. The guidelines consider: A) MRI system and techniques; B) patient selection; C) trial design; D) analysis of results. Priorities for future research are also indicated.