OBJECTIVE. Voluntary patient motion is a common cause of image degradation during MRI and leads to repeated scanning, decreasing efficiency, and increasing costs. We hypothesized that providing an educational pamphlet to patients before their MRI examination could improve image quality and decrease the number of repeated sequences needed because of motion artifacts.
SUBJECTS AND METHODS. Over 12 months, we recruited patients undergoing MRI for any neurologic condition. The control group received a routine safety questionnaire concerning MRI scanning. The intervention group was given an additional pamphlet describing the examination and graphically emphasizing the value of remaining still during scanning; comprehension was confirmed by questionnaire. The radiology technologists performing the examinations were blinded to group assignments; they recorded the number of repeated sequences needed because of motion artifacts and assessed image quality on a scale of 0 to 4 (0 = unusable, 4 = perfect).
RESULTS. The number of patients requiring repeated MRI sequences (control group vs intervention group: 40 vs 20, respectively; p = 0.009) and the total number of repeated MRI sequences (52 vs 27, p = 0.004) decreased in the group who read the pamphlet compared with the control group.
CONCLUSION. Providing a simple educational pamphlet to patients before their MRI examinations that illustrated motion degradation and emphasized the need to remain still significantly reduced the number of repeated sequences deemed necessary by the MRI technologist.
MRI has become an indispensable diagnostic tool over the past 25 years, often surpassing CT as the method of choice for diagnosing various diseases and conditions. Among the advantages of MRI are its lack of ionizing radiation and its superior soft-tissue contrast resolution . Among the disadvantages are the expense, artifacts, and diminished speed. A particularly common artifact is image degradation due to patient motion . This artifact is closely related to the long scanning times needed for MRI, as patients are required to lie relatively motionless for up to 5 minutes or longer to obtain optimum image quality. Because of the high cost of MRI, there is substantial interest in reducing, eliminating, or avoiding the artifacts that undermine the quality of MRI scans.
Motion artifacts result from excessive patient movement during the data acquisition phase and typically cause the signal to be mis-registered during reconstruction. Misregistration in effect disperses portions of the image, causing overlap between regions or loss of portions of the image altogether. Therefore, imaging features not only become blurred but also may appear as superimposed ghosts on adjacent or regional voxels [1, 3, 4]. Of particular concern is the reduced conspicuity of lesions. Although technology has yielded hardware and software to compensate for motion artifacts [1, 4], it is best to avoid the source movement altogether. Some movement is involuntary and therefore difficult to intrinsically reduce, but much patient motion remains unintentional and is thus amenable to improvement.
Among the causes of voluntary patient motion during MRI scanning is high patient anxiety. Excessive anxiety during scanning compromises the patient's level of self-control, thus reducing his or her ability to remain still in the scanner [5–9]. Patients who are not anxious during the scanning period exhibit less motion, and lower anxiety during MRI scanning improves image quality [6, 7, 10].
Increasing patient education and patient-staff interaction before an MRI examination can result in reduced motion artifact, not only by reducing anxiety [11, 12] but also by addressing simple ignorance regarding the effect of motion on image degradation. The information provided to patients should pertain more to the technique than to its benefit or purpose . This suggestion has been corroborated by Johnson , who concluded that preprocedural information targeted at reducing patient anxiety should concentrate on education regarding the procedure, the sensations the patient is likely to experience, and the overall length of the procedure.
This study sought to prospectively determine whether providing information regarding the procedure and the need to remain still to patients before scanning, using an inexpensive pamphlet that is easy to distribute, would lower the incidence of MRI motion artifacts and improve the efficiency of a busy MRI practice. Although the study focused on brain and spine MRI, the problem of motion artifact applies to MRI of any portion of the body. However, motion problems in the abdomen and chest are more complex and require more complex solutions, and such studies were not included in this study.
Subjects and Methods
This blinded prospective study compared two patient groups. At the MRI appointment before scanning, one group received a routine questionnaire that was concerned with only MRI safety (control group), whereas the other group received the safety information and an additional pamphlet that described the importance of minimizing patient movement to improve scan quality. All scanning was conducted in two clinical facilities at our institution using either one of two 3-T scanners (Trio, Siemens Healthcare) or one of three 1.5-T scanners (Avanto, Siemens Healthcare; Espree, Siemens Healthcare).
This study received approval from our institutional review board (IRB). Because no identifying patient information was collected, the IRB waived the informed consent requirement.
Data were collected within a 6-month span (from December 13, 2010, through May 11, 2011) during a pilot period and then over three intensive sessions, each about 10 days long. All enrolled patients were outpatients who arrived at our scanning facility located in a hospital setting to undergo any neurologic MRI examination. Neurologic scans (either brain or spine) comprised approximately 70% of all MRI scans during the study period. Patients were excluded if they could not read English or clearly could not comprehend the pamphlet (e.g., intellectually impaired, young school-age), as assessed by the intake assistant.
The control group was not given any material other than the routine safety questionnaire. All patients in the intervention group were given an additional pamphlet as a supplement before they underwent MRI. The pamphlet provided additional instructions, highlighted important advice, and emphasized that patients should try not to move during the scanning procedure. These instructions were supported by visual examples comparing MRI scans with motion artifacts and those without motion artifacts (Fig. 1).
Patients arriving for their MRI examination during any of the data collection periods were asked by the receptionist to participate in the study. Those who chose to participate were assigned a consecutive number without any patient identifier. The ordering of assigning groups—control versus intervention (pamphlet)—was not specified and left to the discretion of the receptionist whose assignments showed no preference or pattern.
Before undergoing scanning, patients in the intervention group were asked to read the educational pamphlet and then complete a questionnaire. The questionnaire was composed of the following three questions: Is this your first MRI scan? Did you read the pamphlet? and What is the most important instruction to follow while in the scanner? The lead MRI administrator then collected the questionnaire and took the patient, regardless of group assignment, to the scanner so that the technologist performing the MRI examination was unaware of the patient's group assignment. Patients in the control group were not given the pamphlet or questionnaire.
Over the course of the study, a total of 22 technologists with a wide range of experience were involved. To assess and record the quality of the examination, the technologist was given a scan evaluation sheet for every patient he or she scanned. The sheet contained only the patient's assigned study number, so the technologist remained blinded to the patient's group assignment. After each MRI examination, the technologist completed the scan evaluation in which he or she was asked to list the total number of repeated sequences due to patient motion. The technologist then gave the completed scan evaluation sheet to the lead MRI administrator.
The number of repeated MRI sequences, which we used as a surrogate measure of patient motion, was compared between the control and intervention groups. A two-sided Fisher exact test was used, with statistical significance defined as α < 0.05. To determine sample size, we conducted a power analysis of the data collected during the pilot data collection session and then expanded the study size on the basis of these data. With a sample size of 200 control subjects and 200 intervention subjects, the study has a power of 80% in comparing the need for a repeated sequence.
Patients assigned to the intervention group who explicitly indicated on the questionnaire that they had not read the pamphlet were counted as members of the control group. Patients whose questionnaire responses were ambiguous because they indicated they read the pamphlet but did not state the main lesson from the pamphlet (to stay still during scanning) were excluded from the analysis.
The receptionist approached a total of 640 potential subjects, 628 of whom participated. During the pilot data collection period, 12 patients served as control subjects and 26 patients received the intervention; the second data collection period involved 47 control patients and 51 intervention patients; the third involved 99 control patients and 95 intervention patients; and the last data collection period involved 149 control patients and 149 intervention patients. A total of 307 control patients and 321 intervention patients. The increasing size of each group was based on interim analyses to obtain sufficient power. Nine intervention patients stated “No” to having read the pamphlet, and their data were switched to the control group. Thus, overall, the study involved 316 control patients and 315 intervention patients. Only seven intervention patients had no previous MRI experience (2.2%); the prevalence in the control group is unknown because they were not given a questionnaire.
As shown in Table 1, of the 316 control patients, 40 required repeated sequences because of patient motion. Because some patients required multiple repeated sequences, there was an overall total of 52 repeated sequences for the control group, yielding a rate of 0.17 motion artifact–related repeated sequences per examination. Conversely, in the intervention group of 315 patients, only 20 required repeated sequences as a result of patient motion, with an overall total of 27 total sequences, yielding a rate of 0.09 motion-related repeated sequences per examination. Patients in the intervention group required significantly fewer repeated sequences in total than patients in the control group (p = 0.004). Furthermore, significantly fewer patients required repeated sequences after the intervention compared with those in the control group (p = 0.009). One of the seven first-time MRI patients explicitly stated “No” to having read the pamphlet and required two repeated sequences, whereas the remaining six required no repeated sequences.
TABLE 1: Comparison of Repeated MRI Scans Between Patients Receiving Standard Education Versus Those Receiving a Pamphlet With Additional Instructions to Reduce Anxiety and Motion
No. of examined patients
No. of repeated sequences due to patient motion
No. of patients requiring at least one repeated sequence
Average no. of repeated sequences per examination
Motion artifacts, the most common cause of MR image degradation, arise from a variety of sources. Voluntary and unintentional patient motion (e.g., coughing, scratching, shifting legs) and involuntary patient motion (e.g., respiration, cardiac pulsation) account for most artifacts visible on MRI scans. Patient motion disperses the MRI signal, altering local phase and amplitude, to produce blurring and ghosting of the image. Acquisition techniques commonly used to correct for motion artifacts include propeller imaging techniques, navigator pulses, signal averaging, gradient-moment nulling, and cardiac and respiratory gating. Despite these technologic advances, the highest-quality images are obtained from a motionless patient; thus, it is more preferable to prevent motion artifacts before they occur than to correct them during acquisition.
Although motion that is not involuntary may be considered “voluntary,” that term is misleading; most “voluntary motion” is better termed “unintentional motion.” For example, motion related to anxiety, pain, or coughing is not voluntary but is unintentional. Several factors can account for unintentional patient movement during an MRI examination. Anxiety concerning the procedure can cause patient motion; excessive anxiety has the effect of reducing the patient's self-inhibition, leading to movement and, in turn, to motion artifacts. Claustrophobia, likely resulting from anxiety, also contributes to patient movement during scanning. A lack of knowledge regarding the procedure has been shown to contribute to patient anxiety and panic [5, 15–17]. Last, simple ignorance regarding the effect of motion on image degradation is also common.
The educational pamphlet we tested addresses two causes of unintentional motion: ignorance and anxiety. Regarding the former, the pamphlet follows previously established guidelines for providing preprocedural educational information with the goal to build awareness of the importance of holding perfectly still and the significance of motion degradation. Unlike a technologist's verbal instructions before scanning, the pamphlet can graphically show the effects of motion on image quality and potentially can increase awareness to a higher level. The pamphlet vigorously and repeatedly directed patients to remain still in the scanner, and this instruction was supported by multiple MR images graphically depicting the impact of patient motion on MRI scans. Note that the lesions displayed in the pamphlet as examples cannot be too large because even a severely motion-degraded image can still reveal a gross abnormality and thereby indicate the need for repeated imaging, perhaps with anesthesia. The danger is with smaller lesions that will be completely obscured. Perhaps most important is that the pamphlet showed patients how motion would distort their scans and would obviously impair diagnosis, thereby engaging the patients' self-interest as they realize their disease state could be misinterpreted because of an action they can control.
Regarding the issue of anxiety, there is a close relationship between increased anxiety and increased motion, and investigators have shown that efforts to reduce anxiety will lead to improved image quality [5, 12–14], Although anxiety measures were not obtained in our study, the information from the pamphlet can reduce anxiety by providing the patient with a greater sense of internal control [15, 18].
Note that the pamphlet was additional information given to the patient before the standard verbal instructions from all technologists to all patients both before and during the MRI examination. The relative effect of the pamphlet versus the technologist is unclear because scanning a patient without a technologist's instructions would not meet today's standard of care. Thus, the effect of the pamphlet is strictly an improvement on the already-existing educational benefit provided by the technologist's instructions.
The advantages of this study include that the study group was composed of patients in a clinical setting rather than paid volunteers and that the intervention was a simple, easy-to-distribute, low-cost pamphlet. An additional advantage is the use of the number of sequences repeated because of patient motion as an objective measure of data quality. Initially an additional outcome measure was included involving each technologist's subjective score of image quality, but the scores among the technologists varied greatly, most likely a problem of a lack of uniform definitions of terms. For example, what one technologist would label with the descriptor “moderate” motion, another technologist might label with the descriptor “mild.” However, most technologists have a uniform sense of image quality regarding the need to repeat a sequence degraded by motion artifact, which transcends labeling descriptors. Therefore, the use of the number of repeated sequences to quantify motion artifacts and image degradation was most likely superior to subjective scales or grading systems. Although neuroradiologists would have provided superior assessments of image quality than the technologists, neuroradiologists do not routinely perform that assessment because patients are typically out of the scanner before they review the images. Therefore, the most significant practical measure of image quality is repeated sequences, which is determined at the discretion of technologists. This method was also adopted to study the practical clinical impact of the intervention in a typical hospital setting.
This work contributes to the earlier literature [5–14] by reporting results for a significantly larger sample size; for example, the largest study referenced had nearly 200 patients and most had fewer than 100. Also, whereas most other studies compared anxiety levels before and after MRI, this work focused on motion artifacts. As a result, the methods of this study were easy to implement, did not required extensive testing, and could be applied widely. Last, whereas many other studies focused on various disease groups or subsets of MRI examinations, this study examined the overall trend for all patients undergoing neurologic imaging in a clinical setting.
Future studies would do well to include an anxiety evaluation before and after scanning. These values could be compared across the control and intervention groups to determine whether the pamphlets had an effect on patient anxiety. The effect of providing patients with recordings of the noises and instructions they will hear while in the MRI unit several days before scanning could also be tested. Further studies could include more patients to sufficiently power the group undergoing MRI for the first time. The low number of first-time MRI patients was likely because of the nature of the MRI center used, which is located within a large tertiary hospital. Alternatively, this study could be repeated at community MRI locations where the fraction of first-time MRI patients is likely much higher. Data regarding the prevalence of first-time MRI scanning were not obtained from the control group, but the low fraction seen in the intervention group (2.2%) is likely comparable to that of the control group; however, both numbers are likely too low to yield statistical significance in a subgroup analysis. Although the English language was exclusively used in this study, the images in the pamphlet transcend any language; thus, the pamphlet can easily be translated into any language for the benefit of patients in all regions.
This study showed that educational information provided to patients before scanning significantly decreased the number of patients who voluntarily move and produce motion artifacts and also halved the total number of sequences repeated because of patient motion. There are obvious benefits associated with halving the quantity of repeated sequences for any MRI center such as improved efficiency because fewer time-consuming repeated sequences are needed, which not only translates into superior patient care but also offers financial benefits. If each MRI examination requires an average of eight 3-minute sequences acquired over 40 minutes, with an average Medicare reimbursement charge of about $500 per examination, and if each repeated sequence adds approximately 4 minutes to an examination, then this additional time financially represents about 10% of the examination cost, or $50. If one assumes that 1500 examinations typically are performed per MRI machine per year, then following our results, 16.5% of examinations would require at least one repeated sequence, and with 52 repeated sequences per 40 examinations with at least one repeat, a total of 322 repeated sequences would occur every year. The total financial cost of these repeated sequences is roughly $16,000. By reducing the number of repeated sequences by half, a total annual savings of $8000 might be realized per machine, which is much more than the cost of the pamphlets. Not every minute saved through intervention may be used for scheduling additional scans, which are scheduled in specific blocks of time. Nevertheless, this relatively simple intervention may yield potential financial and efficiency savings. In addition, MRI schedules would be less prone to delays, increasing patient satisfaction.
Patients benefit from increased awareness about their MRI examination and the heightened efficiency in several ways. Of most importance is that the quality of patient care will improve because motion artifacts degrade image quality and diagnostic yield. In addition, less time will be spent on repeated sequences, reducing patient time in the magnet and potentially reducing anxiety.
Last, because pamphlets are inexpensive and simple to create, the initial cost is minimal and is easily outstripped by the benefits.
The results of this study show that providing patients with written and visual information before their MRI examination in the form of a simple pamphlet that discusses the procedure and the importance of remaining motionless can significantly reduce both the number of patients requiring repeated MRI sequences and the total number of repeated MRI sequences. Reducing the number of repeated MRI sequences and reducing motion artifacts in MRI scans translate into higher-quality patient care, increased workflow efficiency, and increased financial benefit.
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