Clinical applications of metabolic imaging and endogenous contrast methods

1347523 - Feasibility of 31P MR spectroscopy in the heart paired with routine cardiac MRI in healthy controls and individuals with Friedreich Ataxia

Wednesday, January 25, 2023

5:00 PM – 6:30 PM

Location: Silver Pearl 1

Presenting Author(s)

SS

Suraj D. Serai, PhD

Associate Professor
University of Pennsylvania
Philadelphia, Pennsylvania, United States

Primary Author(s)

SS

Suraj D. Serai, PhD

Associate Professor
University of Pennsylvania
Philadelphia, Pennsylvania, United States

Co-Author(s)

David M. Biko, MD

Assistant Professor
The Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, United States
SM

Shana E. McCormack, MD

Associate Professor
The Children's Hospital of Philadelphia, Pennsylvania, United States
KL

Kimberly Y. Lin, MD

Associate Professor
The Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, United States

Disclosure(s):

David M. Biko, MD: No financial relationships to disclose

Background: 31P MRS allows for the detection of phosphocreatine (PCr), adenosine triphosphate (ATP), and inorganic phosphate (Pi). These compounds are involved in the regulation of the available energy from ATP hydrolysis via the creatine kinase (CK) reaction. In individuals with heart failure, PCr/ATP ratios correlate with the clinical severity of heart failure and are a prognostic indicator of mortality. However, 31P MRS of the heart comes with substantial technical challenges, thus the feasibility of using it to understand rare disease progression in humans is not well established. Friedreich ataxia (FA) is the most common hereditary ataxia. Disease onset is between 10 and 15y, but can present throughout the lifetime, and in most affected individuals, can lead to progressive loss of ambulation and premature mortality. The most common cause of death is complications due to cardiac disease, but early manifestations of the disease are difficult to detect by routine imaging alone. In this study, we explored the feasibility of performing 31PMRS in conjunction with assessment of ventricular mass and function in healthy controls and patients with FA.

Methods:

31P MRS was performed on 3T MRI using a 49.9 MHz fixed tuned transmit receive coil. After acquiring basic cardiac long axis and short axis for anatomic localization, 31P MRS was acquired ECG triggered with a TR: 320 ms, TE: 2.3 ms, NEX: 128, FA: 40 deg, voxel size: 25x25x40 mm, with a scan time of approximately 12 mins. A cine short axis SSFP of the whole heart and a cine 4 chamber SSFP sequence was also performed using the standard cardiac coil. LV volumetry and mass were performed by contouring the endocardial and epicardial borders during end systole and end diastole.

Results:

In this 31P MRS feasibility study (n=9), we were able to successfully perform 31P MRS along with assessment of cardiac and mass function on 2 healthy controls and 7 individuals with FA. Representative images are shown from 31P MRS of the heart of a 28-year-old male healthy volunteer (PCr/Pi = 6.35, PCr/ATP = 0.98, LVEF = 68% with end diastolic volume measuring 69 ml/ m², LV mass = 89 g/m², Stroke volume = 93 cc, LV end diastolic wall thickness = 0.8 cm) (Figure 1) in contrast with 31P MRS of the heart of a 25-year-old male patient with FA (PCr/Pi = 4.11, PCr/ATP = 0.37, LVEF = 71% with end diastolic volume measuring 56 ml/ m², LV mass = 82 g/m², Stroke volume = 68 cc, LV end diastolic wall thickness = 1.5 cm) (Figure 2). Overall, PCr was seen to be substantially decreased in individuals with FA vs controls. Reduced PCr/ATP ratio was seen in individuals with FA (mean = 2.3; n = 7) as compared to healthy controls. In contrast, normal LVEF was observed in both individuals with FA and controls.

Conclusion:

31P MRS is feasible in conjunction with routine cardiac MRI and may enhance our understanding of disease pathophysiology. Further application of this technique could lead to analysis of many complex metabolic pathways and their role in human heart failure.