Non-Contrast Perfusion using Arterial Spin Labeling

We are developing, optimizing, and evaluating arterial spin labeled (ASL) non-contrast perfusion imaging techniques for quantitative blood flow measurements.

Blood flow, which supplies the essential oxygen and nutrients, increases in certain conditions such as cancer through angiogenesis and gets disrupted in other conditions such as chronic kidney disease or lung disease. Non-invasive measurements of blood flow often guide the disease evaluation, treatment choice, and therapeutic monitoring of disease progression. We are evaluating ASL based perfusion techniques for 1) therapy response assessment in cancer and 2) to monitor kidney and lung function.

proton density weighted

Shown: Proton-density weighted image (a), perfusion-weighted image (b) and perfusion-quantified image (c) of the kidneys of a normal human volunteer acquired on a Philips 3 T Ingenia scanner. Prolonged labeling (1.5 seconds) afforded by pCASL on a clinical scanner combined with efficient background signal suppression provided increased signal to noise ratio (SNR).

With the ASL technique that we use, called pseudo-continuous ASL (pCASL), the arterial blood is magnetically labeled in a feeding artery (e.g., abdominal aorta), which is later acquired when the labeled blood perfuse the organ of interest (e.g., kidneys). With this approach, the perfused blood can be quantitated in physiological values (ml/100g/min), using a proton-density weighted image. Absolute quantification in physiological values offers robust means for therapeutic monitoring, regardless of the scanner on which the data are acquired.

Shown: Sagittal proton density weighted image (a), SPECT perfusion image (b), ASL perfusion-weighted image (c), and quantified ASL perfusion map (d) in a 28-year-old healthy male volunteer. Arrows indicate signals from major vessels that are visible on ASL perfusion images (c,d), and seen as regions of photopenia on SPECT images (b).

Sagittal proton density weighted image