Given a heart rate of 85 bpm, if a 24-frame gated heart study is acquired, the length of each frame in milliseconds is:

To determine the length of each frame in a 24-frame gated heart study based on a heart rate of 85 beats per minute, we need to first calculate the duration of one cardiac cycle, which can be derived from the heart rate.

A heart rate of 85 beats per minute means that there are 85 cardiac cycles occurring within one minute (60 seconds). The duration of a single cardiac cycle in seconds can be calculated using the formula:

[

\text{Duration of one cycle (seconds)} = \frac{60 \text{ seconds}}{85 \text{ beats}} \approx 0.70588 \text{ seconds}

]

Next, convert this duration into milliseconds (since there are 1000 milliseconds in a second):

[

0.70588 \text{ seconds} \times 1000 = 705.88 \text{ milliseconds}

]

Given that the gated study consists of 24 frames, we can find the duration of each frame by dividing the total duration of the cardiac cycle by the number of frames:

[

\text{Length of each frame (milliseconds)} = \frac{705.88 \text{ milliseconds}}{24} \approx 29.4 \text{ milliseconds