Contrast Enhanced Magnetic Resonance Imaging of the Brain Using Gadolinium-DTPA

This study was designed to assess whether contrast-enhanced dynamic 1H magnetic resonance imaging (DMRI) can be used to detect the effects of the loop diuretic furosemide and the vasoactive peptide angiotensin II on tubular water reabsorption in the rat kidney. A bolus of gadolinium-DTPA-dimeglumine (Gd-DTPA) (0.025 or 0.1 mmol/kg) was used as a contrast agent. The signal intensity in the magnetic resonance images relative to the precontrast signal intensity (RSI) was assessed as a function of time in the cortex and medulla. In the cortex, no differences were observed between high and low bolus injection, and between different treatment groups and controls. In the medulla, RSI patterns were different between high and low bolus, with the high bolus showing lower RSI values, because of T2 shortening at high Gd-DTPA concentrations. No difference was observed between controls and angiotensin II-infused animals. This is in line with the finding that angiotensin II did not alter medullary water reabsorption, as evidenced by unchanged urine flow and osmolality compared with controls. Medullary RSI patterns during furosemide infusion differed markedly from controls, in a manner suggesting that a lower concentration of Gd-DTPA was present compared with controls. This agrees with the well-known inhibiting effect of furosemide on medullary water reabsorption. It was concluded that, with the method used, small concentration differences of Gd-DTPA in the cortex resulting from small changes of plus or minus 20% in tubular water reabsorption, previously found to be present by direct micropuncture measurements, cannot be detected in rats. However, large changes in renal concentrating ability do result in different RSI patterns in the medulla.

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Magnetic resonance imaging of the cranial nerves in congenital, traumatic, and vascular diseases: a pictorial essay

Radiologia Brasileira ◽

10.1590/0100-3984.2020.0039 ◽

2021 ◽

Vol 54 (3) ◽

pp. 185-192 ◽

Cited By ~ 1

Author(s):

Mariana Dalaqua ◽

Felipe Barjud Pereira do Nascimento ◽

Larissa Kaori Miura ◽

Fabiano Reis ◽

Márcio Ricardo Taveira Garcia ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Cranial Nerves ◽

Three Dimensional ◽

Vascular Diseases ◽

Resonance Imaging ◽

Complex Anatomy ◽

Contrast Enhanced ◽

Pictorial Essay ◽

The Brain

Abstract The cranial nerves, which represent extensions of the functional structures of the brain, traverse the head and neck. They are connected to various cranial structures and are associated with several diseases. An in-depth understanding of their complex anatomy and normal imaging appearance allows the examiner to identify and characterize abnormalities with greater precision. One important tool for evaluating the cranial nerves is contrast-enhanced magnetic resonance imaging, especially three-dimensional steady-state free precession sequences, which provide high soft-tissue and spatial resolution, despite the slenderness of the nerves. In most cases, imaging findings are nonspecific. Therefore, to narrow the differential diagnosis, it is necessary to take a full patient anamnesis, perform a focused physical examination and order laboratory tests. In this pictorial essay we review, illustrate and discuss, from a pathophysiological perspective, congenital, traumatic, and vascular diseases of the cranial nerves.

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