Short name: Gd-HP-DO3A, generic name: Gadoteridol injection, chemical compound: Gd-1,4,7-tris(carbonylmethyl)-10-(2'-hydroxypropyl)-1,4,7,10-tetraazacyclododecane
(ProHance®) A nonionic MRI contrast agent with a low molecular weight complex of gadolinium (macrocyclic chelate, which tightly binds the Gd atom).
Gadoteridol does not cross the blood brain barrier. If the barrier is damaged, gadoteridol will penetrate into lesions such as tumors. It also highlights areas of increased vascularity so it has been used to improve the delimitation of lesions elsewhere in the body.
Apart from its paramagnetic effects, gadoteridol has no pharmacological activity in the body. After intravenous injection, most of the dose is excreted unchanged in the urine within 24 hours.

See also Contrast Agents and ProHance®.

Short name: Gd-EOB-DTPA, generic name: Gadoxetic acid, chemical compound: Gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid
Primovist™ (formerly Eovist®) is a nonionic water-soluble liver tissue-specific MRI contrast agent with positive enhancement. The agent allows detection and differentiation of hepatic tumors due to specific uptake by healthy liver tissue, but not by tumors in the affected organ. Gd-EOB-DTPA has hepatocyte-specific properties, but provides earlier perfusion information acquired within first ten minutes. Hepatocyte uptake generally occurs beyond 10 minutes.

Rectal staging is necessary for the preoperative assessment of intra- and extramural tumor infiltration or the decision for adjuvant radio-chemotherapy. One indication of MRI with luminal contrast enhancement is small bowel enteroclysis after duodenal intubation for visualization of inflammatory bowel wall thickening and other complications.
"Double contrast" enhancement of the bowel lumen is the administration of plain water or water with methylcellulose along with heavily T2 weighted sequences or contrast enhanced T1 weighted sequences.
Several oral contrast agents have been used for small bowel MRI: Mannitol, metamucil, locust bean gum, and PEG. All provide sufficient bowel distension and homogeneity, but suffer from side effects such as diarrhea. The volume of PEG or mannitol administered must be not too large in order to achieve the best compromise between distension and acceptance by the patient.
MR colonography with positive bowel lumen enhancement requires higher concentrations of paramagnetic agents compared to the available dedicated enteral contrast agents, IV compounds are used to dope water enemas for this purpose.
Some investigators advocate negative bowel enhancement with Contrast Agents to suppress high signal bowel content in MRCP ( Magnetic resonance cholangiopancreaticography ). The use of a mixture of metamucil and 20 ml of gadolinium chelate provides good homogeneity and good tolerance without diarrhea.

Macromolecular Gd labeled albumins are a new class of contrast agents with a wide range of use e.g., MR angiography, breast MRI, perfusion MRI, Lung perfusion, etc.
Marketed gadolinium-based albumin-bound contrast media are e.g., MultiHance®, and Vasovist™; other prototypes are in development. Malignant tumors often show an increased uptake and metabolism of plasma proteins, especially albumin. Contrast agents with large molecules are delivered to all tissues, but only accumulate in those with leaky vessels by tumor capillaries (tumor neovessels). MRI tumor perfusion studies with Gd labeled albumin can show the success of tumor therapy by quantitative decrease in MR signal of the malignant tissue after therapy compared to before. In addition, the study of tumor sensitivity to a therapy with drug-labeled albumins seems possible.
After renal transplantation, MRI may diagnose albuminuria caused by glomerular disease with an albumin-bound blood pool contrast agent

See also Blood Pool Agents, Intravascular Contrast Agents, Contrast Enhanced MRI.

Short name: Gd-DTPA-PEG, generic name: Gd-DTPA-PEG polymers, chemical compound: Gadolinium DTPA polyethylene glycol, central moiety: Gd2+, relaxivity: r1=6.0, B0=1.0 T
A substance under development (preclin.) as an intravascular MRI contrast agent for MR angiography and capillary permeability detection.