Biomedical subjects

Peter D Gatehouse

Publications and source records attributed to Peter D Gatehouse.

At least 19 recordsLinked to original sources

PubMed2006

Improved turbo spin-echo imaging of the heart with motion-tracking.

PURPOSE: To improve dark-blood and short tau inversion recovery (STIR) prepared turbo spin-echo (TSE) imaging of the heart, particularly in the basal short-axis plane where cardiac misregistration between the preparation and imaging phases is high. MATERIALS AND METHODS: In the first approach (tracked), the basal short-axis plane was labeled and tracked over the cardiac cycle. The slice-selective 180 degrees dark-blood and STIR preparation pulses were then independently positioned on the appropriately timed labeled images. In the second approach (offset), the preparation pulses were output in the same orientation as the imaging plane, but with a user-defined slice offset that was derived from the labeled data. Both approaches were compared with the standard untracked dark-blood STIR TSE sequence (7-mm slice thickness) in 10 healthy volunteers. RESULTS: For typical preparation slice thicknesses, tracked and offset TSE images were superior to the untracked images (both P < 0.01). For the more mobile right ventricle (RV), the image quality of the tracked images was superior to that of the offset images (P < 0.05). CONCLUSION: Tracking the through-plane motion of the heart between preparation and imaging phases improves the quality of thin-slice basal short-axis TSE images, particularly for the more mobile RV.

Algorithms↗

PubMed2006

Development of a novel optimized breathhold technique for myocardial T2 measurement in thalassemia.

PURPOSE: To develop a reproducible fast spin-echo (FSE) technique for accurate myocardial T2 measurement with application to iron overload assessment in thalassemia. MATERIALS AND METHODS: An FSE sequence was developed to permit acquisition of multiple TE images in one breathhold (BH-FSE). A dynamic black-blood scheme was introduced to better cancel blood signal. A nonselective refocusing train was also adopted to suppress stimulated echoes. The optimized technique was tested on phantoms and then applied to 10 normal volunteers and 10 thalassemia patients. Interstudy reproducibility was measured on all the 20 subjects. RESULTS: The mean difference in T2 values was 1.7% from phantom experiments between BH-FSE and the conventional spin-echo (SE) technique. High contrast BH-FSE images were acquired from human subjects, with minimal stimulated echoes and effective blood suppression (P = 0.0005). The coefficient of variation for interstudy reproducibility was 4.3%. T2 values from thalassemia patients were substantially lower than those from the normal subjects (45.2 +/- 26.1 msec vs. 56.9 +/- 8.4 ms, P = 0.02). CONCLUSION: The dynamic black-blood T2 sequence is a fast reproducible acquisition that compares favorably with conventional techniques, is robust to motion artifacts, and yields high blood-myocardium contrast. This technique may provide a useful tool in thalassemia and other scenarios requiring myocardial T2 quantification.

Adolescent↗

PubMed2005

Applications of phase-contrast flow and velocity imaging in cardiovascular MRI.

A review of cardiovascular clinical and research applications of MRI phase-contrast velocity imaging, also known as velocity mapping or flow imaging. Phase-contrast basic principles, advantages, limitations, common pitfalls and artefacts are described. It can measure many different aspects of the complicated blood flow in the heart and vessels: volume flow (cardiac output, shunt, valve regurgitation), peak blood velocity (for stenosis), patterns and timings of velocity waveforms and flow distributions within heart chambers (abnormal ventricular function) and vessels (pulse-wave velocity, vessel wall disease). The review includes phase-contrast applications in cardiac function, heart valves, congenital heart diseases, major blood vessels, coronary arteries and myocardial wall velocity.

Blood Flow Velocity↗

PubMed2005

Interstudy reproducibility of three-dimensional volume-selective fast spin echo magnetic resonance for quantifying carotid artery wall volume.

PURPOSE: To assess the interstudy reproducibility of a three-dimensional volume-selective, fast spin echo (FSE) magnetic resonance technique for the assessment of carotid artery wall volume, which is a marker for total carotid plaque volume. MATERIALS AND METHODS: Interstudy reproducibility was evaluated in 10 subjects with evidence of carotid artery atherosclerotic disease on carotid Doppler ultrasonography. Subjects were scanned twice with an interscan time of one hour to four days. The carotid artery was imaged in cross-section, and the total carotid arterial wall volume (TWV) was calculated by subtraction of the total carotid lumen volume from the total outer carotid vessel volume. RESULTS: The mean carotid TWV for the scans was 741 and 734 mm3, respectively, with no significant difference (mean difference 7 mm3; P = 0.5). The time for each study was approximately 20 minutes. The standard deviation of the differences between the measurements was 33 mm3, yielding an interstudy coefficient of variation of 4.4%. Sample size calculations showed that 16 patients would enable this difference in plaque volume over time to be detected with 80% power at a P value of 0.05. CONCLUSION: Volumetric analysis with CMR of carotid artery plaques using a three-dimensional volume-selective FSE is efficient with good interstudy reproducibility, and is well suited for longitudinal studies of progression of carotid atheroma with reasonable sample sizes.

Aged↗

PubMed2005

Optimization of the arterial input function for myocardial perfusion cardiovascular magnetic resonance.

PURPOSE: To determine how injection rate, cardiac function, and breathhold influence the arterial input function (AIF), in order to optimize the AIF in the clinical setting for quantitative myocardial perfusion cardiovascular magnetic resonance (CMR). MATERIALS AND METHODS: Gd (0.1 mmol/kg) bolus was injected at 3, 5, or 7 mL/second in 35 patients. In each cardiac cycle during the first-pass, a series of saturation recovery (SR) fast low-angle shot (FLASH) low resolution images with exponentially increasing SR delay times were acquired. Signal intensity (SI) time measurements were made from a region of interest (ROI) drawn in the ascending aorta (AA). The calculation of short T1s and thus peak Gd concentration [Gd] was performed by fitting the mean ROI SI against SR delay times. RESULTS: The mean peak [Gd] in the AA increased as injection rate increased from 3 mL/second (5.0 mM), to 5 mL/second (7.1 mM), to 7 mL/second (4 mM) (P < 0.0001). The peak [Gd] increased as the left ventricular stroke volume (LV SV) increased (P = 0.01). Breath holding was not found to influence peak [Gd]. CONCLUSION: In this study, we found that a high injection rate has advantages over lower injection speeds, although the duration of the AIF was apparently not significantly shortened by faster injection. The choice of expiration or inspiration as breathhold did not have a significant influence upon the AIF. Poor cardiac function was associated with a lower peak [Gd], indicating that first pass perfusion measurements in these patients will be suboptimal.

Aorta↗

PubMed2005

3D volume-selective turbo spin echo for carotid artery wall imaging with navigator detection of swallowing.

PURPOSE: To improve 3D volume-selective turbo spin echo (TSE) carotid artery wall imaging by incorporating navigators to reduce artifacts caused by swallowing. MATERIALS AND METHODS: Images were acquired on a Siemens Magnetom Sonata 1.5T scanner. 3D volume-selective TSE scans of the carotid arteries were acquired in six healthy volunteers. A cross-pair navigator placed on the back of the tongue was used to detect swallowing and movement. Two swallowing patterns were tested: 1) a single swallow approximately halfway through the scan time, at the center of k(z), and 2) repeated swallowing as often as possible throughout the scan period. Images were acquired with and without navigators for comparison. Signal intensity in the lumen was quantified for the quality of blood suppression, and the clarity of the vessel wall in the common carotid was ranked by four independent blinded observers. RESULTS: In general, lower signal intensity was recorded in the lumen, and decreased blurring and ghosting were observed on scans with navigator control. This reduction in lumen signal intensity signifies an improvement in the black-blood imaging technique. The differences likely reflect the improved double inversion/blood suppression efficiency due to cycles being rejected when the heart rate changed at the point of swallowing, or decreased motional blurring/ghosting of tissue when the navigator is used, or a combination of these two effects. A statistical analysis of image quality showed a significant difference between navigated and non-navigated scans as scored by four independent, blinded observers. For both swallowing patterns, the mean score for the navigator images was on average 0.6 greater than that of non-navigator images (on a scoring scale of 0-5, where 0 = no vessel visible, and 5 = good delineation and blood suppression) and P-values for all observers were less than 0.01. Overall, the central swallow scans were scored higher than the repeated swallow scans. One reason for this may be the fact that the heart rate increased on swallowing, and this often lasted for one or two cardiac cycles after the navigator returned to the normal acceptance position. The effect of the increased heart rate after swallowing is likely to have an effect on double inversion blood suppression efficiency. Therefore, the increased amount of heart rate changes with repeated swallowing may have a greater adverse effect, even if the navigator rejects data views during the swallowing motion. CONCLUSION: The clarity of vessel wall delineation and the apparent efficiency of blood suppression are reduced by swallowing during acquisition. Both motion blurring and quality of blood suppression are factors that can be improved with the use of a navigator accept/reject method.

Artifacts↗

PubMed2005

Magnetic resonance imaging of cortical bone with ultrashort TE pulse sequences.

PURPOSE: Normal adult cortical bone has a very short T(2) and characteristically produces no signal with pulse sequence echo times (TEs) routinely used in clinical practice. We wished to determine whether it was possible to use ultrashort TE (UTE) pulse sequences to detect signal from cortical bone in human subjects and use this signal to characterise this tissue. SUBJECTS AND METHODS: Seven volunteers and 10 patients were examined using ultrashort TE pulse sequences (TE=0.07 or 0.08 ms). Short and long inversion as well as fat suppression pulses were used as preparation pulses. Later echo images were also obtained as well as difference images produced by subtracting a later echo image from a first echo image. Saturation pulses were used for T(1) measurement and sequences with progressively increasing TEs for T(2)* measurement. Intravenous gadodiamide was administered to four subjects. RESULTS: Signal in cortical bone was detected with UTE sequences in children, normal adults and patients. This signal was usually made more obvious by subtracting a later echo image from the first provided that the signal-to-noise ratio was sufficiently high. Normal mean adult T(1)s ranged from 140 to 260 ms, and mean T(2)*s ranged from 0.42 to 0.50 ms. T(1) increased significantly with age (P<.01). Increased signal was observed after contrast enhancement in the normal volunteer and the three patients to whom it was administered. Reduction in signal from short T(2) components was seen in acute fractures, and increase in signal in these components was seen with new bone formation after fracture malunion. In a case of osteoporosis, bone cross-sectional area and signal level appeared reduced. CONCLUSION: Signal can be detected from normal and abnormal cortical bone with UTE pulse sequences, and this can be used to measure its T(1) and T(2)* as well as observe contrast enhancement. Difference images are of value in increasing the conspicuity of cortical bone and observing abnormalities in disease.

Adolescent↗

PubMed2005

Interstudy reproducibility of quantitative perfusion cardiovascular magnetic resonance.

PURPOSE: To determine the interstudy reproducibility of quantitative first-pass perfusion cardiovascular magnetic resonance with comparison of 2 previously described analysis techniques. There is no published data on the interstudy reproducibility of perfusion cardiovascular magnetic resonance which can be used to determine the significance of longitudinal changes in myocardial perfusion after pharmacologic or therapeutic interventions with defined sample sizes. METHODS: Sixteen subjects (7 normal volunteers, 9 patients with coronary artery disease) had rest and adenosine stress perfusion cardiovascular magnetic resonance studies on two separate visits. A short axis slice was studied on each visit using a fast low-angle shot sequence. The global and regional myocardial perfusion reserve indices were calculated using 2 methods: model based constrained deconvolution with the Fermi function, and normalized upslopes. Reproducibility was defined as the standard deviation of the measurement differences, divided by the mean (coefficient of variation). RESULTS: The reproducibility of global myocardial perfusion reserve indices was 21% in normal volunteers, which was similar to that in patients with coronary artery disease (CAD) (23%, p = .88). The reproducibility of regional myocardial perfusion reserve indices was 28% (p = .45 vs. global analysis). The reproducibility of global MPRi was superior with Fermi deconvolution compared with normalized upslopes (21% vs. 41%, p = .02). CONCLUSION: At this stage of clinical development, the reproducibility of quantitative perfusion cardiovascular magnetic resonance is good, and superior using Fermi deconvolution in preference to upslope analysis.

Adenosine↗

PubMed2005

Comparison of hybrid echo-planar imaging and FLASH myocardial perfusion cardiovascular MR imaging.

The purpose of this study was to compare fast single-shot gradient-echo (FLASH) and hybrid echo-planar imaging (EPI) magnetic resonance (MR) technologies regarding the relative contrast-to-noise ratio (CNR), spatiotemporal resolution, size of inducible perfusion defects, and presence of artifacts in patients with coronary artery disease (CAD). Fifteen patients with CAD underwent rest and adenosine stress gadolinium first-pass perfusion cardiovascular MR examinations with EPI and FLASH. The study was approved by the local ethics committee, and each subject gave written informed consent. The spatial resolution of the two sequences was made similar in nine patients, and the temporal resolution was made similar in six. The images were assessed for CNR, artifact, and size of inducible perfusion defects. The CNR was significantly higher with the EPI sequence, whether matched for spatial (32 vs 22 [46%], P < .001) or temporal (35 vs 23 [51%], P < .001) resolution. There was no significant difference in scoring for artifact or area and transmural extent of inducible perfusion defects with EPI and FLASH, whether matched for temporal or spatial resolution. Further work is warranted to determine the relative diagnostic accuracy of the two techniques.

Aged↗

PubMed2004

MR imaging of degenerative disc disease in the lumbar spine with ultrashort TE pulse sequences.

OBJECTIVE: The objective of this study was to assess the feasibility of using ultrashort TE (UTE) pulse sequences to image the lumbar spine. MATERIALS: Pulse sequences of TE=0.08 ms were used to image the lumbar spine in 5 normal subjects and 14 patients with degenerative disease. Contrast enhancement was administered in 11 cases. RESULTS: The sequences showed high signal in the anterior and posterior longitudinal ligaments, the cartilaginous end plate, the annulus fibrosus, the ligamentum flavum, interspinous ligaments and insertions of ligaments. Normal contrast enhancement was seen in these structures. Enhancement of hypertrophied ligaments and scar tissue was readily identified. Long T2 suppression techniques were useful in distinguishing enhancement of scar tissue from veins. Enhancement in discs was more obvious than with conventional sequences. In a case of thalassaemia bands of high signal were seen in the intervertebral discs parallel to the end plates. CONCLUSION: The UTE sequences offer new options for visualizing discs, scar tissue, ligaments and other structures of the lumbar spine in health and disease.

Adult↗

PubMed2004

Magnetic resonance imaging of periosteum with ultrashort TE pulse sequences.

PURPOSE: To assess the values of pulse sequences with ultrashort echo times (0.08 msec) for detecting and characterizing periosteum. MATERIALS AND METHODS: Two normal volunteers aged 33 and 58 years and 12 patients aged seven to 55 years were studied. A total of 10 of the patients had contrast enhancement with intravenous Gadodiamide. Two ovine tibias were examined before and after the periosteum was stripped from the bone. RESULTS: High signal regions were observed adjacent to cortical bone in all parts of the skeleton imaged. They were generally more conspicuous after fat suppression and contrast administration. In the ovine tibia there was a reduction in the high signal normally seen at the surface of the bone after periosteal stripping. The detached periosteum produced a high signal. Mean T(2)* values for adult human periosteum ranged from 5.3 to 11.4 msec. After enhancement the signal intensity increased. In two patients with tibial fractures, increased periosteal signal was seen and this showed marked enhancement. Signals from periosteum could be simulated by fat, contrast-enhanced blood and artifacts. CONCLUSION: The periosteum can be visualized with ultrashort echo time pulse sequences in health and disease.

Adult↗

PubMed2004

Comparison of spiral and FLASH phase velocity mapping, with and without breath-holding, for the assessment of left and right coronary artery blood flow velocity.

PURPOSE: To develop high temporal resolution coronary artery spiral phase velocity mapping sequences and to compare the results obtained with those from FLASH sequences. MATERIALS AND METHODS: Velocity curves were obtained in eight left and eight right coronary arteries using breath-hold interleaved spiral (BH_SP), free-breathing interleaved spiral (FB_SP), breath-hold segmented FLASH (BH_FL), and free-breathing FLASH (FB_FL) sequences. Spatial resolution, temporal resolution, and acquisition durations (cardiac cycles) were as follows-BH_SP: 0.9 mm x 0.9 mm, 30 msec, 20 cycles; FB_SP: 0.9 mm x 0.9 mm, 42 msec, 100 cycles; BH_FL: 0.9 mm x 1.8 mm, 70 msec (effective), 20 cycles; FB_FL: 0.9 mm x 1.8 mm, 30 msec, 480 cycles. Peak systolic, peak diastolic, and mean velocities were compared between sequences. RESULTS: For left and right arteries, the FB_SP velocity profiles closely followed those from the FB_FL sequence. By comparison, the BH_FL sequence failed to resolve the sharp peaks in the temporal velocity profiles of the right coronary artery, significantly underestimating the peak systolic (88 mm/second vs. 252 mm/second, P < 0.001), peak diastolic (114 mm/second vs. 153 mm/second, P < 0.01), and mean (56 mm/second vs. 93 mm/second, P < 0.001) velocities. For the less mobile left artery, the peak systolic, peak diastolic, and mean velocities were also underestimated by the BH_FL sequence, although this only reached statistical significance for the systolic peak (80 mm/second vs. 135 mm/second, P < 0.01), 142 mm/second vs. 168 mm/second, (P = ns), and 87 mm/second vs. 101 mm/second, (P = ns) respectively. CONCLUSION: We have shown that the FB_SP sequence developed agrees well with the FB_FL sequence, while the study duration is reduced by a factor of 10 for the same spatial resolution. By comparison, the BH_FL sequence underestimates flow velocities, particularly in the more mobile right coronary artery.

Adult↗

PubMed2004

Accurate assessment of the arterial input function during high-dose myocardial perfusion cardiovascular magnetic resonance.

PURPOSE: To develop a method for accurate measurement of the arterial input function (AIF) during high-dose, single-injection, quantitative T1-weighted myocardial perfusion cardiovascular magnetic resonance (CMR). MATERIALS AND METHODS: Fast injection of high-dose gadolinium with highly T1 sensitive myocardial perfusion imaging is normally incompatible with quantitative perfusion modeling because of distortion of the peak of the AIF caused by full recovery of the blood magnetization. We describe a new method that for each cardiac cycle uses a low-resolution short-axis (SA) image with a short saturation-recovery time immediately after the R-wave in order to measure the left ventricular (LV) blood pool signal, which is followed by a single SA high-resolution image with a long saturation-recovery time in order to measure the myocardial signal with high sensitivity. Fifteen subjects were studied. Using the new method, we compared the myocardial perfusion reserve (MPR) with that obtained from the dual-bolus technique (a low-dose bolus to measure the blood pool signal and a high-dose bolus to measure the myocardial signal). RESULTS: A small significant difference was found between MPRs calculated using the new method and the MPRs calculated using the dual-bolus method. CONCLUSION: This new method for measuring the AIF introduced no major error, while removing the practical difficulties of the dual-bolus approach. This suggests that quantification of the MPR can be achieved using the simple high-dose single-bolus technique, which could also image multiple myocardial slices.

Contrast Media↗

PubMed2004

Respiratory reordered UNFOLD perfusion imaging.

PURPOSE: To propose a respiratory reordered UNFOLD (RR-UNFOLD) imaging sequence to significantly reduce the amount of k-space data required for first-pass MR myocardial perfusion imaging. MATERIALS AND METHODS: Rapid acquisition of high-resolution imaging data is essential to detailed quantitative analysis of first-pass myocardial perfusion. Existing MR sequences have explored the full capacity of the imaging hardware to reduce the acquisition window within each cardiac cycle while maintaining the desired spatial resolution. Further improvement in perfusion imaging will require a more efficient use of the information content of the k-space data. The method uses prospective diaphragmatic navigator echoes to ensure that temporal filtering of UNFOLD is carried out on a series of images that are spatially registered. An adaptive real-time rebinning algorithm is developed for the creation of static image subseries related to different levels of respiratory motion. Issues concerning the temporal smoothing of tracer kinetic signals are discussed, and a solution based on oversampling of the central k-space is provided. The method is assessed in 10 normal subjects without the administration of contrast agent, and further validated by administration of Gd-DTPA in 10 patients at rest. RESULTS: The results of this study show that RR-UNFOLD significantly extends the applicability of UNFOLD to perfusion imaging, which yields a 40% reduction in image artifact when the same amount of k-space information is used. CONCLUSION: The scan efficiency achieved can be used in combination with MR hardware improvements for extending the three-dimensional spatial coverage and shortening the data acquisition window to provide detailed information on regional myocardial perfusion abnormalities.

Adult↗

PubMed2004

Spiral phase velocity mapping of left and right coronary artery blood flow: correction for through-plane motion using selective fat-only excitation.

PURPOSE: To develop a method of correcting both right and left coronary artery flow velocities for the through-plane motion of the vessel, in order to allow details in the temporal flow profiles to be viewed. MATERIALS AND METHODS: The methods developed use selective excitation and velocity mapping of the epicardial fat surrounding the artery, either in a separate acquisition (temporal resolution = 22 msec) or interleaved with the water-excitation acquisition (temporal resolution = 44 msec) used to determine coronary blood flow velocities. The two methods were compared in 10 right and 13 left coronary arteries in healthy volunteers. RESULTS: For the right coronary arteries, correction for through-plane motion significantly reduces the mean systolic flow velocity (75.3 mm/second vs. 90.0 mm/second, P < 0.01), while the mean diastolic flow velocity is unchanged (96.8 mm/second vs. 94.5 mm/second, P = ns). The resulting profiles are biphasic, with approximately equal flow in systole and diastole. For the left arteries, correction for through-plane motion reduces the mean systolic flow velocity (25.0 mm/second vs. 72.8 mm/second, P < 0.001), resulting in the expected diastolic predominant flow profiles. For the right arteries, there were no significant differences in the mean systolic and mean diastolic velocities after correction with the separate fat-excitation acquisition, and after correction the poorer temporal resolution combined water excitation/fat excitation acquisition. However, for the left coronary arteries, the combined water excitation/fat excitation acquisition resulted in a slight reduction in the mean diastolic velocity (121.5 mm/second vs. 130.9 mm/second, P < 0.05). CONCLUSION: Selective excitation of the surrounding epicardial fat enables through-plane correction of both left and right coronary flow velocities, enabling the temporal details of flow velocity to be viewed. With a combined WE/FE acquisition, this can be performed without extending the study duration; however, the reduced temporal resolution and temporal mismatch of the excitations results in a blunting of rapidly changing flow profiles. As such, it may be less suitable for the left coronary artery, which has a greater range of through-plane motion than the right, and correction using separate WE and FE acquisitions, or the adjacent myocardium, may be preferable.

Adult↗

PubMed2004

Human imaging of phosphorus in cortical and trabecular bone in vivo.

Phosphorus was imaged in vivo in human cortical and trabecular bone and the T(1) and T(2) (*) were measured. An ultrashort TE (UTE) pulse sequence (TE = 70 microm) was used with half pulse excitation and radial mapping of k-space from the center out. T(2) (*) was measured using multiple echo times and T(1) was measured both by saturation recovery and by a method using different RF pulse amplitudes. Seven normal subjects (32-85 years) were examined. Phosphorus was imaged, with a true in-plane resolution of 2.9 x 2.9 mm and a signal-to-noise ratio (SNR) of 19:1, in both cortical and trabecular bone. The mean T(2) (*) value was 207 +/- 12 micros, and the mean T(1) value was 8.6 +/- 3.0 sec. Images and measurements were obtained in realistic times on a clinical MR system. This may provide a new approach to characterizing disease of bone.

Adult↗

PubMed2004

Magnetic resonance imaging of the knee with ultrashort TE pulse sequences.

BACKGROUND: We wished to assess the feasibility of imaging the knee with ultrashort TE (UTE) pulse sequences. SUBJECTS AND METHODS: Five volunteers and 16 patients were studied with UTE (TE=0.08 ms) sequences including later echoes. Conventional fat-suppressed images and difference images were also produced by subtracting a later echo from the first. Gadodiamide enhancement was used. RESULTS: High signal was obtained in tendons, ligaments, menisci and periosteum. Normal contrast enhancement was seen in these structures. Deep and superficial layers were seen in the articular cartilage. Cartilage defects were identified. The red zone could be differentiated from the white zone of the meniscus. Meniscal tears and degeneration were observed with low signal on subtraction images. Enhancement was seen within the anterior and posterior cruciate ligaments and associated scar tissue. CONCLUSION: Ultrashort TE imaging provides new options to visualize anatomy, manipulate conspicuity, observe contrast enhancement and demonstrate disease of the knee.

Adult↗

PubMed2004

Off-frequency tuning error artifact in steady-state free precession cine imaging due to adjacent air-filled bowel.

Identification of common cardiovascular magnetic resonance (CMR) artifacts is important to optimal image acquisition quality and the avoidance of mistaken clinical diagnosis. We describe an off-frequency tuning error artifact observed during rapid steady-state free precession acquisitions in three patients and resulting in a dramatic appearance within the right and left ventricles. These artifacts were associated with large, adjacent air pockets within a loop of bowel or stomach and were eradicated by retuning of the magnetic resonance scanner's frequency. Awareness of this artifact, its cause and correction, should improve diagnostic image quality and avoid clinical diagnostic confusion. This report also heightens the need for a more robust shimming sequence for cardiac studies.

Adult↗