MRI of patients with suspected scrotal or testicular lesions: diagnostic value in daily practice.

OBJECTIVE: The purpose of this study was to evaluate retrospectively the diagnostic value of MRI in the care of patients with suspected scrotal disorders. MATERIALS AND METHODS: Testicle-containing scrotal compartments were evaluated by examiners blinded to all clinical information in an interdisciplinary consensus reading after MRI was performed with standardized T1-, T2-, and contrast-enhanced T1-weighted sequences. Image quality was evaluated on an increasing 4-point scale. Nineteen binary diagnostic parameters were allocated 1 point each if the diagnosis was correct and were summarized into categories in terms of localization, pattern, and characterization of the lesions. The results were compared with histopathologic results in 22 cases, with the surgical report in one case, and with a combined clinical reference comprising medical reports and scrotal ultrasound, follow-up, or laboratory results in 61 cases. RESULTS: A total of 165 scrotal compartments containing testicles were analyzed in 84 patients; three patients underwent single-sided orchiectomy before MRI. The mean image quality score was 3.2 ± 0.7. Percentage of maximum diagnostic points, sensitivity, specificity, and positive and negative predictive values were 100% for localization of scrotal lesions and analysis of the pattern of testicular lesions. The values were 95%, 87%, 97%, 88%, and 97% for analysis of the pattern of nontesticular lesions and 95%, 92%, 97%, 91%, and 97% for classification of scrotal lesions. CONCLUSION: Scrotal lesions can be reliably detected, precisely localized, and characterized with MRI in everyday practice. The differential diagnosis was narrowed by use of MRI. This finding is of great clinical importance because more precise treatment strategies can be determined and surgical exploration or orchiectomy avoided by more patients.

The adverse events and hemodynamic effects of adenosine-based cardiac MRI.

OBJECTIVE: We wanted to prospectively assess the adverse events and hemodynamic effects associated with an intravenous adenosine infusion in patients with suspected or known coronary artery disease and who were undergoing cardiac MRI. MATERIALS AND METHODS: One hundred and sixty-eight patients (64 ± 9 years) received adenosine (140 µg/kg/min) during cardiac MRI. Before and during the administration, the heart rate, systemic blood pressure, and oxygen saturation were monitored using a MRI-compatible system. We documented any signs and symptoms of potential adverse events. RESULTS: In total, 47 out of 168 patients (28%) experienced adverse effects, which were mostly mild or moderate. In 13 patients (8%), the adenosine infusion was discontinued due to intolerable dyspnea or chest pain. No high grade atrioventricular block, bronchospasm or other life-threatening adverse events occurred. The hemodynamic measurements showed a significant increase in the heart rate during adenosine infusion (69.3 ± 11.7 versus 82.4 ± 13.0 beats/min, respectively; p < 0.001). A significant but clinically irrelevant increase in oxygen saturation occurred during adenosine infusion (96 ± 1.9% versus 97 ± 1.3%, respectively; p < 0.001). The blood pressure did not significantly change during adenosine infusion (systolic: 142.8 ± 24.0 versus 140.9 ± 25.7 mmHg; diastolic: 80.2 ± 12.5 mmHg versus 78.9 ± 15.6, respectively). CONCLUSION: This study confirms the safety of adenosine infusion during cardiac MRI. A considerable proportion of all patients will experience minor adverse effects and some patients will not tolerate adenosine infusion. However, all adverse events can be successfully managed by a radiologist. The increased heart rate during adenosine infusion highlights the need to individually adjust the settings according to the patient, e.g., the number of slices of myocardial perfusion imaging.

Contrast-enhanced CMR in patients after percutaneous closure of the left atrial appendage: a pilot study.

BACKGROUND: To evaluate the feasibility and value of first-pass contrast-enhanced dynamic and post-contrast 3D CMR in patients after transcatheter occlusion of left atrial appendage (LAA) to identify incorrect placement and persistent leaks. METHODS: 7 patients with different occluder systems (n = 4 PLAATO; n = 2 Watchman; n = 1 ACP) underwent 2 contrast-enhanced (Gd-DOTA) CMR sequences (2D TrueFISP first-pass perfusion and 3D-TurboFLASH) to assess localization, artifact size and potential leaks of the devices. Perfusion CMR was analyzed visually and semi-quantitatively to identify potential leaks. RESULTS: All occluders were positioned within the LAA. The ACP occluder presented the most extensive artifact size. Visual assessment revealed a residual perfusion of the LAA apex in 4 cases using first-pass perfusion and 3D-TurboFLASH indicating a suboptimal LAA occlusion.By assessing signal-to-time-curves the cases with a visually detected leak showed a 9-fold higher signal-peak in the LAA apex (567 ± 120% increase from baseline signal) than those without a leak (61 ± 22%; p < 0.03). In contrast, the signal increase in LAA proximal to the occluder showed no difference (leak 481 ± 201% vs. no leak 478 ± 125%; p = 0.48). CONCLUSION: This CMR pilot study provides valuable non-invasive information in patients after transcatheter occlusion of the LAA to identify correct placement and potential leaks. We recommend incorporating CMR in future clinical studies to evaluate new device types.

High-resolution 3D non-contrast-enhanced, ECG-gated, multi-step MR angiography of the lower extremities: comparison with contrast-enhanced MR angiography.

OBJECTIVE: To determine the diagnostic value of non-contrast-enhanced, 3D-high-resolution, ECG-gated, multi-step MR angiography (non-ceMRA) of the lower extremities using a modified turbo-spin-echo technique in comparison to 1.0-molar contrast-enhanced MR angiography (ceMRA) in patients with suspected peripheral vascular disease (PVD). METHODS: Fifty consecutive patients underwent non-ceMRA before ceMRA within the same session. We assessed examination time, image quality, localisation and severity of stenosis. RESULTS: Examination time was shorter for ceMRA (12 ± 4 min) compared with non-ceMRA (28 ± 6 min, p < 0.001). The image quality of the aorta-iliac, femoral and combined popliteal and lower leg arteries was inferior for non-ceMRA (2.8 ± 0.8/3.3 ± 0.8/3.3 ± 0.9) versus ceMRA (4.7 ± 0.8/4.8 ± 0.6/4.8 ± 0.7) on a 5-point scale with 5 for maximum quality (p < 0.01). CeMRA offered more assessable data sets than non-ceMRA (98% vs. 90%). For detecting stenosis >50% or occlusions of pelvic and femoral arteries using non-ceMRA the sensitivity, specificity, positive and negative predictive values were 94%, 86%, 67% and 98% and for popliteal and lower leg arteries 93%, 87%, 69% and 98%, respectively. CONCLUSION: We demonstrated that 3D non-ceMRA represents a very promising technique in patients with lower extremities PVD and could be used as an alternative if gadolinium-based contrast agents cannot be administered.

High-resolution 3D unenhanced ECG-gated respiratory-navigated MR angiography of the renal arteries: comparison with contrast-enhanced MR angiography.

OBJECTIVE: The aim of this study is to determine the diagnostic value of high-resolution 3D unenhanced ECG-gated respiratory-navigated MR angiography (MRA) of the renal arteries using a steady-state free precession (SSFP) technique in comparison with 1.0-molar contrast-enhanced MRA in patients with suspected renal artery stenosis. SUBJECTS AND METHODS: Forty-five consecutive patients underwent unenhanced MRA before contrast-enhanced MRA within the same session. We assessed examination time, image quality, renal artery architecture, and localization and severity of renal artery stenosis. RESULTS: Examination time was shorter for contrast-enhanced MRA (mean ± SD, 12 ± 3 minutes) than for unenhanced MRA (19 ± 3 minutes; p < 0.001). On a 5-point scale, the image quality was similar for contrast-enhanced MRA (3.8 ± 1.0) and unenhanced MRA (4.0 ± 1.3; p = 0.24). Contrast-enhanced MRA offered more assessable data sets than did unenhanced MRA (95% vs 90%); however, unenhanced MRA had more data sets with maximum image quality (49% vs 30%). There was moderate agreement in stenosis grading between both MRA techniques (κ = 0.51; p < 0.001), but in only one case (1.3%) we found mismatch of more than one severity stenosis grade (stenoses > 75%). Sensitivity, specificity, and positive and negative predictive values of unenhanced MRA to detect renal artery stenoses greater than 50% were 75%, 99%, 75%, and 99%, respectively. CONCLUSION: We show that SSFP 3D unenhanced MRA is a very promising technique for patients with suspected renovascular disease and could be used as an alternative if gadolinium-based contrast agents cannot be administered.

MRI after implantation of a novel femoral closure device following intra-arterial catheterisation: implications for subsequent contrast-enhanced MR angiography.

OBJECTIVE: To assess MRI safety aspects and artefacts of a novel femoral artery closure device during contrast-enhanced MR angiography in patients following intra-arterial catheterisation. METHODS: Ten consecutive patients underwent MRI within 24 h of coronary angiography and placement of a femoral artery closure device. We used a T2-weighted gradient-echo MRI sequence to measure the device-related artefact size in comparison with a phantom image, phase-contrast flow measurement proximal to, at the level of and distal to the device to quantify potential differences in flow velocity and contrast-enhanced 3D gradient-echo MR angiography to differentiate potential femoral artery stenosis from device-related artefacts. RESULTS: The mean size of the oval-shaped artefact was 8.4 x 6.6 mm (+/-1.0 x 0.8 mm) and was almost identical to the maximum artefact size of the phantom measurement (8.3 x 5.7 mm). Device placement did not result in an increased peak velocity (proximal 69 +/- 23 cm/s, at the level of 64 +/- 11 cm/s and distal to the device 63 +/- 12 cm/s, p = 0.67). The mean artefact penetration into the vessel lumen was 0.5 +/- 0.5 mm (percentage vessel narrowing 7.0 +/- 6%; range 0-16%). CONCLUSION: The MR conditional StarClose femoral artery closure device was used safely within 24 h of deployment at 1.5 T. Despite clip-related artefacts MR angiography will allow for easy differentiation of clip-related artefacts from high-grade atherosclerotic stenosis.

First experiences with contrast-enhanced first-pass MR perfusion imaging in patients with primary, benign cardiac masses and tumour-like lesions.

The aim of this study was to evaluate the diagnostic value of contrast-enhanced first-pass perfusion MRI in patients with suspected cardiac masses and tumour-like lesions. Twenty patients underwent contrast-enhanced first-pass saturation-recovery steady-state-free-precession perfusion MRI in addition to clinical MRI. Eleven diagnostic parameters were analysed blinded in consensus by three observers: localisation (paracardiac/mural/intracavitary), malignancy (benign/malignant) and first-pass enhancement pattern (homogeneous/heterogeneous as well as non-perfused/hypoperfused/iso-perfused/ hyperperfused). The results were compared to combined references comprising histology, cytology, medical and surgical reports, echocardiography, chest X-ray, coronary angiography and regular MRI. Also, we analysed if additional first-pass perfusion confirmed, changed or reduced the number of differential diagnoses compared to clinical MRI. All cardiac masses or tumour-like lesions were correctly localised and scored as benign lesions. For homogeneous perfused lesions the sensitivity, specificity, positive and negative predictive value was 94/100/100/67%, 100/94/67/100% for heterogeneous perfused lesions, 92/100/100/88% for non-perfused, 100/94/75/100 for hypoperfused, 100/100/100/100% for hyperperfused and for isoperfused lesions. In 17/2/1 cases perfusion MRI confirmed, reduced or increased the number of potential differentials. First-pass perfusion MRI provides valuable information in patients with benign cardiac masses or tumour-like lesions. Further experience is needed to underline these preliminary observations.

Dynamic contrast-enhanced MRI before and after transcatheter occlusion of patent foramen ovale.

OBJECTIVE: The purpose of this study was threefold: to evaluate the diagnostic accuracy of dynamic contrast-enhanced MRI compared with transesophageal echocardiography (TEE) in the detection of patent foramen ovale (PFO) and of residual shunts after occlusion of PFO, to define cutoff values for semiquantitative analysis of signal intensity-time curves, and to compare the diagnostic accuracy of visual detection with that of semiquantitative analysis. SUBJECTS AND METHODS: Forty-three patients (18 women, 25 men; mean age, 51 +/- 14 years) who underwent TEE for suspicion of PFO (n = 26, 19 patients with and seven without PFO) or for routine assessment for residual shunt after transcatheter PFO occlusion (n = 17, nine patients with and eight without residual shunt) were consecutively enrolled to undergo contrast-enhanced MRI (saturation recovery steady-state free precession sequence). The images were analyzed both visually and semiquantitatively for arrival of contrast agent in the left atrium before arrival in the pulmonary veins during a Valsalva maneuver. TEE results were used as the clinical reference. RESULTS: With an area under the signal intensity-time curve of 0.85, height of the first initial peak in signal intensity in the left atrium proved to be the best discriminator in right-to-left shunt detection. For a cutoff value of 129% (from baseline signal intensity) for this parameter, sensitivity and specificity were 90% (17/19) and 100% (7/7) in patients without PFO devices and 56% (5/9) and 88% (7/8) in patients with PFO devices. The diagnostic accuracy of both visual assessment and semiquantitative analysis was consistently superior before PFO device implantation than after device implantation. The diagnostic accuracy of visual shunt assessment was better than that of semiquantitative shunt assessment in patients with PFO occluders (sensitivity, 67% [6/9] correctly diagnosed; specificity, 88% [7/8]) and those without PFO occluders (sensitivity, 95% [18/19]; specificity, 100% [7/7]). CONCLUSION: At present, MRI cannot replace TEE for the exclusion of potential embolic sources, such as thrombus in the left atrial appendage. However, MRI can be an attractive alternative noninvasive technique if TEE is technically unfeasible or is declined by patients.

Time-resolved contrast-enhanced MR angiography of the thorax in adults with congenital heart disease.

OBJECTIVE: The aim of this study was to evaluate the diagnostic value of time-resolved contrast-enhanced MR angiography in adults with congenital heart disease. SUBJECTS AND METHODS: Twenty patients with congenital heart disease (mean age, 38 +/- 14 years; range, 16-73 years) underwent contrast-enhanced turbo fast low-angle shot MR angiography. Thirty consecutive coronal 3D slabs with a frame rate of 1-second duration were acquired. The mask defined as the first data set was subtracted from subsequent images. Image quality was evaluated using a 5-point scale (from 1, not assessable, to 5, excellent image quality). Twelve diagnostic parameters yielded 1 point each in case of correct diagnosis (binary analysis into normal or abnormal) and were summarized into three categories: anatomy of the main thoracic vessels (maximum, 5 points), sequential cardiac anatomy (maximum, 5 points), and shunt detection (maximum, 2 points). The results were compared with a combined clinical reference comprising medical or surgical reports and other imaging studies. Diagnostic accuracies were calculated for each of the parameters as well as for the three categories. RESULTS: The mean image quality was 3.7 +/- 1.0. Using a binary approach, 220 (92%) of the 240 single diagnostic parameters could be analyzed. The percentage of maximum diagnostic points, the sensitivity, the specificity, and the positive and the negative predictive values were all 100% for the anatomy of the main thoracic vessels; 97%, 87%, 100%, 100%, and 96% for sequential cardiac anatomy; and 93%, 93%, 92%, 88%, and 96% for shunt detection. CONCLUSION: Time-resolved contrast-enhanced MR angiography provides, in one breath-hold, anatomic and qualitative functional information in adult patients with congenital heart disease. The high diagnostic accuracy allows the investigator to tailor subsequent specific MR sequences within the same session.

Limited flow reserve in non-obstructed bypass grafts supplying infarcted myocardium: implications for cardiovascular magnetic resonance imaging protocols.

We evaluated flow reserve in non-obstructed bypass grafts supplying infarcted and noninfarcted myocardium. Bypass grafts were examined by phase-contrast flow measurements and myocardial viability was assessed with late enhancement technique. Flow reserve was higher in bypasses supplying normal myocardium compared to those supplying infarcted myocardium (2.9 vs. 1.5, p<.0001). This difference remained significant after adjusting for co-variables. Bypass grafts supplying infarcted myocardium were more likely to have lower flow reserve than those supplying normal myocardium (flow reserve < or =2, 84% vs 18%, p = .0003). Flow reserve is reduced in non-stenosed bypasses supplying infarcted myocardium, likely due to altered microcirculation. Thus, cardiovascular magnetic resonance based bypass assessment must include myocardial viability testing.

Thrombus detection in the left atrial appendage using contrast-enhanced MRI: a pilot study.

OBJECTIVE: Left atrial thrombi are an important cause for embolism-related morbidity and mortality. Transesophageal echocardiography (TEE), the clinical reference, is semiinvasive; thus, we aimed to assess the value of contrast-enhanced cardiovascular MRI for the detection of thrombus in the left atrial appendage. CONCLUSION: The image quality was good for both 2D perfusion (grade 4 +/- 1) and 3D turbo fast low-angle shot (FLASH) (grade 4 +/- 1, n.s.). Compared with TEE, 2D perfusion, 3D turboFLASH, and the combination of both techniques yielded sensitivities of 47/35/44%, specificities of 50/67/67%, positive predictive values of 73/75/80%, and negative predictive values of 25/27/29%, respectively. The size of the thrombus was overestimated by 2D perfusion (66%) and by 3D turboFLASH (25%) and agreement for location and shape of thrombus was 50% and 75% for 2D perfusion and 75% and 50% for 3D turboFLASH, respectively. The TEE thrombus size was significantly larger in patients with true-positive diagnoses by 2D perfusion (148%) and by 3D turboFLASH (151%) when compared with patients with false-negative diagnoses (p < 0.05 for both). No such difference was found for image quality, time delay between TEE and MRI examination, and location and shape of thrombi. Contrast-enhanced MRI lacks diagnostic accuracy for the detection of thrombi in the left atrial appendage. Future technical improvements are essential to establish this technique as a noninvasive alternative to TEE.

Diagnosis of patent foramen ovale using contrast-enhanced dynamic MRI: a pilot study.

OBJECTIVE: The aim of this study was to evaluate the feasibility of dynamic contrast-enhanced MRI for detection of patent foramen ovale. SUBJECTS AND METHODS: Fifteen patients with and five patients without patent foramen ovale underwent transesophageal echocardiography and MRI, which were performed during the Valsalva maneuver. Grading results (grade 0, no patent foramen ovale and grades 1-3, minor to major enhancement due to intracardiac shunt) were assessed visually. Signal-intensity curves in the left atrium and in a pulmonary vein served to underline the diagnosis. RESULTS: The diagnoses of all patients with (15/15) and without patent foramen ovale (5/5) were correct compared with the findings of the reference transesophageal echocardiography. In 12 (60%) of 20 patients, the grading scores were identical, and in four (20%) of 20 patients, the scores differed by more than one grade. Overall, there was a good correlation of grading scores (r = 0.7, p < 0.05). Using signal-intensity curves, we found that the patients with patent foramen ovale showed an additional signal peak in the left atrium before the enhancement of the pulmonary vein because of an intracardiac shunt. In three of 15 patients with patent foramen ovale, an atrial septal aneurysm was correctly diagnosed. CONCLUSION: This pilot study shows that MRI is a new noninvasive method to detect patent foramen ovale and atrial septal aneurysm. A grading is possible but warrants further investigation regarding its predictive value and impact on treatment strategies.

Influence of contrast agent dose and image acquisition timing on the quantitative determination of nonviable myocardial tissue using delayed contrast-enhanced magnetic resonance imaging.

BACKGROUND: Delayed contrast-enhanced magnetic resonance imaging (ceMRI) has been shown to identify areas of irreversible myocardial injury due to infarction (MI) with high spatial resolution, allowing precise quantification of nonviable (hyperenhanced) myocardium. The aim of our study was to investigate the size of nonviable myocardium quantitatively as a function of time post-contrast when inversion time is held constant in patients post-myocardial infarction using two contrast agent (CA) doses. METHODS: Nine patients with chronic MI underwent two MR scans on a 1.5 Tesla system. Contrast-enhanced MRI data in two short-axis (SA) slices were continuously acquired until 40 minutes after CA injection [gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), 0.1 mmol/kg body weight = single dose] interrupted only for a complete stack of SA slices encompassing the entire left ventricle (LV) between minutes 20 and 28. Left ventricular mass showing hyperenhancement was determined. The measurement was repeated on the subsequent day with double dose CA (0.2 mmol/kg body weight). Differences of signal intensities for hyperenhanced, nonhyperenhanced myocardium, and LV cavity were calculated. RESULTS: Total mass of hyperenhancement from a complete SA stack acquired between minutes 20 and 28 was lower for single dose CA [9.0% vs. 14.2% for single and double dose, respectively (p = 0.03)]. Ten to 18 minutes after CA injection, there was no significant difference between the two doses and to an internal reference for both single and double dose. For single dose the image contrast between hyperenhancement and LV cavity was superior (minutes 10 to 16, p < 0.05) but inferior between hyperenhanced and nonhyperenhanced myocardium (minutes 6 to 16, p < 0.05). CONCLUSION: Myocardial infarct size measurements are a function of time postcontrast when inversion time is held constant regardless of the contrast agent dose. These data underscore the fact that a standardized imaging protocol that defines how the appropriate inversion time should be selected is needed for comparison of results obtained at various cMR sites.

Diagnostic value of routine clinical parameters in acute myocardial infarction: a comparison to delayed contrast enhanced magnetic resonance imaging. Delayed enhancement and routine clinical parameters after myocardial infarction.

AIMS: Contrast enhanced magnetic resonance imaging (ceMRI) has been shown to reliably identify irreversible myocardial injury. The aim of this study was to compare the findings on ceMRI with routine clinical markers of myocardial injury in patients with acute myocardial infarction (MI). METHODS AND RESULTS: Twenty-four patients with acute MI were investigated at 1.5 T. The global myocardial function was analysed with a standard cine MR protocol and a stack of short axis slices encompassing the entire left ventricle. Corresponding short axis slices were acquired for delayed ceMRI 15-20 min after the administration of 0.2 mmol gadolinium-DTPA/kg body weight. Mass of hyperenhancement and peak creatine kinase release (peak CK) was determined for each patient. The presenting 12-lead ECG was analysed for ST-elevation on admission and later development of Q-waves. Mass of hyperenhancement correlated moderately well to peak CK (r = 0.65, p < 0.01) and endsystolic volume index (r = 0.55, p < 0.01). Mass of hyperenhancement was inversely correlated to ejection fraction (r = -0.50, p = 0.02). Neither the presence of ST elevation on the admission ECG nor the later development of Q-waves did relate to the transmural extent of hyperenhancement and to the mass of hyperenhancement. CONCLUSION: Mass of hyperenhancement significantly correlates to global myocardial function and to peak CK. However, there is no relationship between the findings in ceMRI and 12-lead ECG abnormalities on admission suggesting an advantage of ceMRI in defining transmural extent and depicting small areas of necrosis.