What is the clinical evidence from this study?

Study design: Observational. Population: Healthy (n=9). Intervention: Submaximal plantar flexion exercise vs. Rest (baseline). Primary outcome: Perfusion in gastrocnemius muscle (mL/100 g/min).

April 14, 2020Open Access

Simultaneous Measurement of Perfusion and T2* in Calf Muscle at 7T with Submaximal Exercise using Radial Acquisition

Key Result

Immediately after submaximal plantar flexion exercise, gastrocnemius muscle perfusion increased from 5 to 79.3 mL/100 g/min and T2* decreased by 6%, demonstrating successful simultaneous quantification at 7T.

Study Design

Type

Observational (n=9)

Multicenter

Structured PICO

Can a novel golden angle radial MRI acquisition technique at 7T simultaneously quantify spatial and temporal changes in muscle perfusion and T2* during recovery from submaximal exercise?

Population

9 healthy adults underwent simultaneous 7T MRI measurement of calf muscle perfusion and T2* during rest and recovery from submaximal plantar flexion exercise.

Intervention

Novel golden angle radial MRI acquisition technique at 7T to simultaneously quantify muscle perfusion and T2* during recovery from submaximal plantar flexion exercise (producing a torque of ~8ft-lb).

Comparator

Baseline measurements at rest.

Outcome

Simultaneous quantification of spatial and temporal changes in muscle perfusion and T2* within calf muscles during recovery from plantar flexion exercise.surrogate

A novel 7T MRI radial acquisition technique successfully enables simultaneous, high-temporal-resolution quantification of skeletal muscle perfusion and oxygenation (T2*) during exercise recovery.

Main Result

Absolute Event Rate: 79.3% vs 5%

Limitations

Assumption that muscle and blood T1 are the same for SATIR approach
Assumption of constant T1 throughout the recovery period post-exercise
Did not quantify the actual work done during the exercise protocol
Use of a surface coil compromised signal to noise from muscle groups at a distance from the coil
Did not validate perfusion measurements with an identical ASL sequence without multi-echo GRE loop

Abstract

Abstract Impairments in oxygen delivery and consumption can lead to reduced muscle endurance and physical disability. Perfusion, a measure of microvascular blood flow, provides information on nutrient delivery. T 2 * provides information about relative tissue oxygenation. Changes in these parameters following stress, such as exercise, can yield important information about imbalance between delivery and consumption. In this study, we implemented novel golden angle radial MRI acquisition technique to simultaneously quantify muscle perfusion and T 2 * at 7T with improved temporal resolution, and demonstrated assessment of spatial and temporal changes in these parameters within calf muscles during recovery from plantar flexion exercise. Nine healthy subjects participated the studies. At rest, perfusion and T 2 * in gastrocnemius muscle group within calf muscle were 5 ± 2 mL/100 g/min and 21.1 ± 3 ms respectively. Then the subjects performed plantar flexion exercise producing a torque of ~8ft-lb. Immediately after the exercise, perfusion was elevated to 79.3 ± 9 mL/100 g/min and T 2 * was decreased by 6 ± 3%. The time constants for 50% perfusion and T 2 * recovery were 54.1 ± 10 s and 68.5 ± 7 s respectively. These results demonstrate successful simultaneous quantification of perfusion and T 2 * in skeletal muscle using the developed technique.

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