[MRI without radiologists--ethical aspects of population based studies with MRI imaging]

Anxiety of patients undergoing CT imaging-an underestimated problem?

RATIONALE AND OBJECTIVES

Prospective evaluation of anxiety in patients undergoing computed tomography (CT) imaging using a standardized state-trait anxiety inventory (STAI-S) and identification of possible risk factors.

MATERIAL AND METHODS

During a 9-month interval, patients undergoing CT were questioned using STAI-S. Additionally, 10 questions concerning specific procedure-related features (claustrophobia, radiation, administration of contrast, and so forth) were added. Moreover, sex, age, admitting subspecialty, organ region, reason for imaging, and prior imaging studies were recorded. Statistical analysis was performed using the Student t test and linear regression analysis; significance level was set to 5%.

RESULTS

Of 6122 patients, 825 patients undergoing CT (14%) were included (67% men; average age, 54 ± 17 years). Average STAI was 42 ± 10 with women (45 ± 11 vs. 41 ± 10; P < .001) and patients who received intravenous contrast (43 ± 10 vs. 42 ± 11; P = .021) showing significantly higher anxiety levels compared to those without contrast. Patients with investigations of their extremities (41 ± 11 vs. 43 ± 10; P = .020) and trauma patients (41 ± 11 vs. 43 ± 10; P = .006) revealed significantly lower STAI results. Patients who had never received a CT scan before showed significantly greater STAI-S values than those with repeat studies (42 ± 10 vs. 41 ± 11; P = .036). Females had greater fears concerning examination results (P < .001), radiation exposure (P = .032), administration of contrast (P = .014), and claustrophobia (P < .001). Patients with known malignancies had a significantly higher level of anxiety concerning their CT results (P = .002).

CONCLUSIONS

Anxiety does not only occur before MRI but also occur before CT. Its sources are manifold and include communication of CT results, administration of contrast agents, radiation exposure, and claustrophobia. In this setting, women seemed to be more receptive than men.

Two basic ethical problems of incidental findings in population-based, non-intervening magnetic resonance imaging (MRI) research

Population-based magnetic resonance imaging (MRI) generates many beneficial consequences for future generations of patients. But there are also some unintended implications for present patients and research subjects. The most important of these implications is the occurrence of incidental findings. In what follows, I will explicate two basic ethical problems concerning incidental findings. I will first argue that the main cause of these two problems lies in the conflicted nature of the medical researcher's role. I will then clarify the two problems, which involves appealing to two basic ethical requirements. The first problem originates from specific empirical conditions of epidemiological MRI research, which indicate shortcomings in the process of obtaining informed consent. The second problem is due to a conflict between obligations of beneficence for the research subjects and the researcher's duty to produce valid and generalizable study results. Finally, I will develop some preliminary perspectives for the solution of these problems.

R2* estimation using "in-phase" echoes in the presence of fat: the effects of complex spectrum of fat

PURPOSE

To investigate R2* mapping robustness in the presence of fat using in-phase echoes, without and with spectral modeling of fat (single-peak and multipeak models, respectively), using varying numbers of echoes.

MATERIALS AND METHODS

Data from 88 volunteers (men/women: 52/36, ages: 55.4 ± 12.2) were randomly chosen according to magnetic resonance imaging (MRI) liver fat-fraction (%), and classified into six fat-fraction groups (1: 20 cases, 0%-<10%; 2: 20 cases, 10%-<20%; 3: 20 cases, 20%-<30%; 4: 20 cases, 30%-<40%; 5: 8 cases >40% liver fat; 6: subcutaneous fat from all cases). R2* maps obtained from five in-phase echoes (echo times: 4.8-23.8 msec) were retrospectively reconstructed using single-peak and multipeak fat modeling. R2* maps were also calculated using different numbers (2-5) of echoes.

RESULTS

Multipeak fat corrected R2* mapping is feasible from in-phase echoes, with noise performance comparable to single-peak R2* when using ≥ 4 echoes. Single-peak R2* showed poor robustness to varying echo time combinations in the presence of fat, where using few echoes resulted in large errors. These errors can be reduced using more echoes, or fully corrected using multipeak fat modeling. The mean R2* increased significantly with increasing fat-fraction when using single-peak R2* for any TE combination (P < 0.001), but did not vary when using multipeak R2* for any TE combination (P ≥ 0.158).

CONCLUSION

R2* mapping uncorrected for spectral complexity of fat contains protocol and fat-dependent errors (lack of robustness) in tissues with high fat content. Accounting for complex fat spectrum improves robustness and accuracy of signal fitting, with modest noise performance loss.