Dynamic contrast‐enhanced MRI of experimental spinal cord injury: In vivo serial studies

Abstract

The progression of experimental spinal cord injury (SCI) was followed with in vivo dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and neurobehavioral studies on postinjury days 0, 2, 4, 7, 10, 14, 17, 21, 28, 35, and 42. Gadopentate dimeglumine (Gd) was administered IV and postcontrast, T 1 -weighted, axial images were acquired repetitively for up to 60 min. Images were analyzed to determine the spatial and temporal evolution of the intensity enhancement. A statistical decision mechanism was developed to objectively detect the enhancement. Strong and rapid enhancement was observed at the epicenter of injury, indicating a significant compromise in blood spinal cord barrier. The enhanced regions in each slice were combined to estimate the area and volume of the lesion. On the day of injury, around 85% of the total cord area at the epicenter showed enhancement within the first 15 min of Gd administration. At the same time, the enhanced volumes attained nearly 40% of the total cord volume and extended axially over 8 mm along the cord. The blood-spinal cord barrier (BSCB) maintains a highly regulated homeostatic environment in the spinal cord (SC) tissue. This regulatory function is sustained by various structures, including the capillary endothelial tight junctions. Under normal physiological conditions, BSCB protects the cord tissue by exhibiting selective permeability to the constituents of intravascular fluid (1,2). A traumatic insult to SC disrupts the structural and biochemical integrity of BSCB. The altered tight junctional patency allows vesicular transport of toxic substances from blood plasma to interstitial spaces. This makes the SC tissue environment unfavorable for neuronal survival, and inhibits tissue repair processes and neurologic recovery. By following the changes in BSCB after injury, important information may be gained about the regions of initial SC tissue damage and a time window for effective drug delivery across the barrier. Assessing BSCB in the late phases of the injury may help evaluate the progression of spinal cord injury (SCI) as well as the efficacy of potential therapeutic interventions.Changes in BSCB permeability can be followed experimentally using intravascularly administered tracers (such as plasma proteins, radiolabeled proteins, and small-molecular-weight molecules) that can cross the compromised barrier (3,4). Although these tracer-based techniques provide valuable information about the status of BSCB, they are either fully invasive, necessitating histological analysis of tissue, or less invasive but still requiring intravenous injection of radio-tracers with subsequent blood sampling along with imaging, as in the case of autoradiography. Moreover, active transport mechanisms involved in some of these tracers may introduce a bias in quantifying the BSCB permeability (4).As an alternative to the above techniques, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), with the exogenous paramagnetic contrast agent gadopentetate-dimeglumine (Gd, for short)...

A pharmacokinetic model for quantitative evaluation of spinal cord injury with dynamic contrast‐enhanced magnetic resonance imaging

“…1, in which the sections of SC (both caudal and rostral to the injury epicenter) did not show any intensity enhancement, despite the presence of blood vessels in the cord. The enhancement patterns were consistent with our previous report (9).…”

“…9). Prior to each scan, the magnet was shimmed with a phantom to minimize the time interval between injury and acquisition of the first image.…”

Diffusion Tensor Imaging at 3 Hours after Traumatic Spinal Cord Injury Predicts Long-Term Locomotor Recovery

“…1A) was essentially lost within the epicenter ( Fig. 1C and D), as reported previously (Bilgen et al, 2001;Narayana et al, 1999). This limitation of standard T2W sequences is currently an obstacle to the interpretation of clinical MR images after human SCI.…”

The relevance of intramedullary high signal intensity and gadolinium (Gd-DTPA) enhancement to the clinical outcome in cervical compressive myelopathy

“…Gd-DTPA is a biologically inert substance, and it diffuses passively through the blood-cord barrier (BCB) into the extracellular space [21]. Gd-DTPA enhancement can indicate a disruption to the parenchyma of the spinal cord and a disturbance in the BCB of the spinal cord [2]. Generally, intramedullary Gd-DTPA enhanced MRI reveal intramedullary lesions, including intramedullary tumors, multiple sclerosis, sarcoidosis, myelitis, and spinal cord infarction [2,14,19].…”

“…Gd-DTPA enhancement can indicate a disruption to the parenchyma of the spinal cord and a disturbance in the BCB of the spinal cord [2]. Generally, intramedullary Gd-DTPA enhanced MRI reveal intramedullary lesions, including intramedullary tumors, multiple sclerosis, sarcoidosis, myelitis, and spinal cord infarction [2,14,19]. Recently, intramedullary Gd-DTPA enhanced MRI findings were known to appear in spinal cord injuries [14,19].…”