Echocardiogram Data Structures and Algorithms 2 — Questions and Answers
Question 1: Which data structure is most appropriate for storing a sequence of Doppler velocity samples acquired over time in echocardiography?
- Hash table
- Array or ring buffer (Correct answer)
- Binary search tree
- Directed acyclic graph
Correct answer: Array or ring buffer
Arrays and ring buffers efficiently store ordered, time-indexed Doppler velocity samples and support fast sequential access.
Question 2: In DICOM echocardiography data, a tag is identified by a Group and Element number pair. What data structure best models the mapping from tag IDs to their values?
- Linked list
- Stack
- Hash map (dictionary) (Correct answer)
- Min-heap
Correct answer: Hash map (dictionary)
A hash map provides O(1) average-case lookup when mapping DICOM tag (Group, Element) pairs to their corresponding values.
Question 3: When processing a cine loop of 100 echocardiographic frames for wall motion analysis, which algorithmic approach most efficiently detects the frame with peak systolic contraction?
- Binary search on unsorted frames
- Linear scan tracking maximum contraction metric (Correct answer)
- Depth-first graph traversal
- Insertion sort followed by mid-point selection
Correct answer: Linear scan tracking maximum contraction metric
A single linear scan (O(n)) through all frames while tracking the maximum contraction metric is the most direct and efficient approach.
Question 4: An echocardiography system queues image reconstruction tasks so the oldest requested task is always processed first. Which data structure implements this behavior?
- Stack (LIFO)
- Priority queue (max-heap)
- Queue (FIFO) (Correct answer)
- Circular doubly linked list
Correct answer: Queue (FIFO)
A FIFO queue ensures the oldest (first-in) task is processed first, matching the described scheduling behavior.
Question 5: 3D echocardiographic volume rendering requires storing voxel adjacency information for surface extraction. Which data structure best represents this spatial graph?
- Adjacency list (Correct answer)
- One-dimensional array
- Call stack
- Hash set
Correct answer: Adjacency list
An adjacency list efficiently represents sparse spatial graphs where each voxel connects to only a small number of neighbors.
Question 6: The Simpson's biplane method for ejection fraction calculates ventricular volume by summing stacked disk areas. What algorithmic pattern describes this computation?
- Divide and conquer
- Numerical integration by summation (Riemann sum) (Correct answer)
- Dynamic programming with memoization
- Greedy selection
Correct answer: Numerical integration by summation (Riemann sum)
Simpson's biplane method approximates volume by summing the areas of discrete cross-sectional disks, which is a discrete numerical integration (Riemann sum).
Question 7: An echo workstation must undo the last five user annotation edits. Which data structure best supports this multi-level undo functionality?
- Queue
- Stack (Correct answer)
- Sorted array
- B-tree
Correct answer: Stack
A stack (LIFO) naturally supports undo operations because the most recent action is always on top and is the first to be reversed.
Echocardiogram Data Structures and Algorithms 2
Which data structure is most appropriate for storing a sequence of Doppler velocity samples acquired over time in echocardiography?