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Recognition of regional hypertrophy in hypertrophic cardiomyopathy using thallium-201 emission-computed tomography:
Insights
Thallium-201 emission-computed tomography effectively characterizes left ventricular hypertrophy (LVH) in hypertrophic cardiomyopathy (HC). This imaging technique aids 2-D sector scans, particularly for detecting apical hypertrophy in HC patients.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Hypertrophic cardiomyopathy (HC) presents diverse left ventricular hypertrophy (LVH) patterns.
- Accurate characterization of LVH is crucial for diagnosing and managing HC.
- Distinguishing between obstructive, nonobstructive HC, and concentric LVH requires precise imaging.
Purpose of the Study:
- To evaluate the configuration of hypertrophied myocardium in different types of HC and LVH.
- To compare the efficacy of thallium-201 emission-computed tomography (Tl-201 SPECT) and 2-D sector scanning in assessing LVH.
- To determine the specific utility of Tl-201 SPECT in identifying apical hypertrophy in HC.
Main Methods:
- Utilized thallium-201 emission-computed tomography (SPECT) and 2-D sector scanning in 30 patients (10 obstructive HC, 10 nonobstructive HC with giant negative T waves, 10 concentric LVH).
- Reconstructed Tl-201 myocardial images into 12-mm slices in 3 planes for analysis.
- Analyzed thickness ratios of ventricular septum, LV posterior wall, and apical wall.
Main Results:
- Obstructive HC showed increased septal wall thickness (septal-to-posterior ratio: 1.45 ± 0.23).
- Nonobstructive HC with giant negative T waves exhibited increased apical wall thickness and apical cavity obliteration (septal-to-apical ratio: 0.66 ± 0.14).
- 2-D sector scanning missed apical hypertrophy in 40% of nonobstructive HC cases, whereas Tl-201 SPECT provided superior detection.
Conclusions:
- Tl-201 SPECT is valuable for evaluating LVH characteristics in HC.
- Tl-201 SPECT complements 2-D sector scanning, especially for detecting apical hypertrophy.
- Advanced imaging is essential for comprehensive assessment of complex HC morphologies.
Abstract:
The configuration of the hypertrophied myocardium was evaluated by thallium-201 emission-computed tomography and 2-dimensional (2-D) sector scan in 10 patients with obstructive hypertrophic cardiomyopathy (HC), 10 with nonobstructive HC with giant negative T waves and 10 with concentric left ventricular (LV) hypertrophy. Thallium-201 myocardial imaging was reconstructed into multiple 12-mm-thick slices in 3 planes. The thickness ratio of the ventricular septum and the LV posterior wall in the short-axis plane and the ratio of the ventricular septum and the apical wall in the long-axis plane were analyzed. In the patients with obstructive HC the ventricular septal wall thickness index was increased, and the ratio of septal to posterior wall thickness index (1.45 +/- 0.23) was greater than that in the patients with nonobstructive HC with giant negative T waves or in those with concentric LV hypertrophy (1.03 +/- 0.20 and 0.98 +/- 0.11, respectively; p less than 0.01 for each). In the patients with nonobstructive HC with giant negative T waves, increased apical wall thickness with apical cavity obliteration was characteristic, and the ratio of ventricular septal to apical wall thickness index (0.66 +/- 0.14) was less than that in the patients with obstructive HC or in those with concentric LV hypertrophy (1.46 +/- 0.38 and 1.04 +/- 0.09, respectively; p less than 0.001 for each). In contrast, technically satisfactory 2-D sector scanning (83%) demonstrated various configurations of the hypertrophied ventricularseptum, but could not detect apical hypertrophy in 4 of the 10 patients with nonobstructive HC with giant negative T waves whose LV cineangiograms demonstrated apical hypertrophy. Thus, thallium-201 emission-computed tomography is useful in evaluating the characteristics of LV hypertrophy and assists 2-D sector scan, especially in patients with apical hypertrophy in HC.