Characterization of carotid atherosclerosis with black-blood carotid plaque imaging using variable flip-angle 3D turbo spin-echo: comparison with 2D turbo spin-echo sequences

Purpose

To compare the diagnostic performance of three-dimensional variable-flip-angle turbo spin-echo and two-dimensional turbo spin-echo sequences in carotid plaque imaging, with histological analysis as the standard of reference.

Materials and methods

Twenty-two patients scheduled for carotid endarterectomy underwent carotid plaque imaging including axial T1-weighted and T2-weighted two-dimensional turbo spin-echo, and coronal T1-weighted and T2-weighted three-dimensional variable-flip-angle turbo spin-echo sequences. The quality of images was visually graded using a three-point scale. The signal ratio of the arterial lumen to the plaque component, and that of the carotid plaque to the ipsilateral submandibular gland was calculated in each sequence. These ratios between two-dimensional and three-dimensional sequences were compared for each plaque component according to the histological category of the plaque.

Results

No significant difference was observed among the overall imaging quality scores of the two-dimensional and three-dimensional sequences, although three-dimensional sequences allowed visualization in arbitrary orientations, as well as depiction of small plaque components such as ulcerations and calcifications. The signal ratio of the plaque to the submandibular gland on T1-weighted three-dimensional sequence was significantly higher than that on two-dimensional sequence (p < 0.01), whereas no significant difference was found between two T2-weighted sequences.The signal ratios of the plaque to the submandibular gland of histology-defined soft plaque components were significantly higher on T1-weighted three-dimensional sequence than on two-dimensional sequence (p < 0.01), whereas no significant differences were observed between two T1-weighted sequences for hard components.

Conclusions

Three-dimensional variable-flip-angle turbo spin-echo is a promising tool for the diagnosis of carotid plaques.     

Malignant spiculated breast masses: dynamic contrast enhanced MR (DCE-MR) imaging enhancement characteristics and histopathological correlation

Aim

Spiculation of breast masses is usually the result of significant desmoplastic reaction. Diminished neovascularization is expected due to sparsely dispersed tumor cells within the lesion. This feature can cause differences in enhancement patterns which can cause pitfalls while evaluating MR images as well. Aim of this study is to explore the enhancement characteristics of malignant spiculated masses and to correlate these findings with histopathological features.

Materials and methods

Eighteen spiculated and seventeen non-spiculated masses depicted with mammography were included in the study. MR imaging was performed with 1.5 T magnet with breast coil. In MR imaging, T2-weighted turbo spin echo (TSE) with fat suppression sequence followed by pre- and post-contrast T1-weighted 3D-fast low angle shot (FLASH) sequences were used. Lesions were evaluated according to enhancement characteristics: early phase enhancement (first 2 min; less than 50%, 50–100% and more than 100%), late phase enhancement (2–6 min; persistent, plateau and washout) and inner enhancement pattern (homogenous, heterogenous and rim). Desmoplasia and lymphocyte infiltration was classified as mild, moderate and severe. MR images and histopathological findings (desmoplasia, lymphocyte infiltration and grade) of both groups were compared.

Results

Mean ages of patients in spiculated and non-spiculated-mass groups were 55.07 (41–71) and 47.35 (31–62), respectively. Mean diameter of lesions was 17.3 mm (10–31 mm) for spiculated masses while non spiculated masses were 15.8 mm (6–40 mm). There were statistically significant differences between late phase enhancement, persistent enhancement, plateau and washout (p < 0.05). Intergroup comparison of desmoplasia revealed significant difference between severe versus and mild, moderate (p < 0.05).

Conclusion

Spiculated malignant lesions are supposed to contain intense desmoplastic reaction. On DCE-MR images they can show persistent enhancement pattern more often than non-spiculated lesions.     

T2-weighted MR imaging of the liver: Qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

Objective

To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver.

Materials and methods

Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences.

Results

SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001).

Conclusion

SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.     

Improved in vivo detection of cortical lesions in multiple sclerosis using double inversion recovery MR imaging at 3 Tesla

Objective

To investigate the impact of a higher magnetic field strength of 3 Tesla (T) on the detection rate of cortical lesions in multiple sclerosis (MS) patients, in particular using a dedicated double inversion recovery (DIR) pulse sequence.

Methods

Thirty-four patients with clinically isolated syndromes or definite MS were included. All patients underwent magnetic resonance imaging (MRI) at 1.5 T and 3 T, including T2-weighted turbo spin echo (TSE), fluid-attenuated inversion recovery (FLAIR) and DIR sequences. All images were analysed for focal lesions categorised according to their anatomical location.

Results

The total number of detected lesions was higher at 3 T across all pulse sequences. We observed significantly higher numbers of lesions involving the cortex at 3 T using a DIR sequence. DIR at 3 T showed 192% more pure intracortical (p?<?0.001) and 30% more mixed grey matter-white matter lesions (p?=?0.008). No significant increase in cortical lesions could be detected on the FLAIR and T2-weighted images. Using the T2-weighted and FLAIR sequences, significantly more lesions could be detected at 3 T in the infratentorial, periventricular and juxtacortical white matter.

Conclusion

DIR brain MR imaging at 3 T substantially improves the sensitivity of the detection of cortical lesions compared with the standard magnetic field strength of 1.5 T.     

Accuracy of thoracic aortic measurements assessed by contrast enhanced and unenhanced magnetic resonance imaging

Aim

To assess, whether unenhanced balanced steady-state-free precession sequences provide axial thoracic aortic measurements comparable to contrast enhanced magnetic resonance angiography with good intra- and interobserver agreement.

Materials and methods

Enhanced and unenhanced sequences of the thoracic aorta in 23 consecutive patients were evaluated. Axial thoracic aortic diameters were measured at predefined levels by two independent readers. Pearson's correlation coefficient and Bland–Altman analysis were used to compare enhanced and unenhanced sequences. t-Test was used to determine possible significant differences between the measurements obtained by enhanced and unenhanced sequences. A p-value of less than .05 indicated statistical significance. Intraclass correlation coefficient and Bland–Altman were used for inter- and intraobserver correlation and agreement.

Results

There was no significant difference in diameter measurements between enhanced and unenhanced sequences (ascending aorta, p = 0.98; descending aorta, p = 0.52). Bland–Altman revealed good agreement between enhanced and unenhanced sequences for ascending (mean bias, −0.01 cm; with 95% limits of agreement, ±0.30 cm) and descending aortic diameters (mean bias, 0.05 cm; with 95% limits of agreement, ±0.30 cm). Inter- and intraobserver agreement (mean bias, less than ±0.15; with 95% limits of agreement, less than ±0.42 cm for all measurements) as well as correlation (r > 0.8 for all measurements) were excellent.

Conclusion

Unenhanced balanced steady-state-free precession sequences enable rapid and accurate determination of axial thoracic aortic diameters with excellent inter- and intraobserver agreement, but without the risk of contrast media associated side-effects.     

A systematic comparison of two pulse sequences for edema assessment in MR-mammography

Objective

Perifocal edema, defined as high T2w signal intensity around an enhancing lesion has been described as a specific feature of malignancy. In clinical MR-mammography (MRM), both fatsat and non-fatsat T2w sequences are available. However, there is no consensus on which technique should be used for edema assessment. Consequently, this investigation was performed to compare two commonly used pulse sequences for edema assessment in MRM.

Materials and methods

321 consecutive patients from a 22 month period were included in this investigation. Further selection criteria were histopathological verification of enhancing lesions and absence of presurgical chemotherapy or biopsy, resulting in 108 malignant and 107 benign lesions. All underwent MRM according to international guidelines including a non-fatsat T2w-TSE sequence (TR/TE: 8900/207 ms) and a short tau inversion recovery fatsat sequence (STIR, TR/TE: 8420/70 ms). All images were acquired in the same orientation (axial) and slice thickness. Two experienced radiologists in consensus rated presence of perifocal edema according to an ordinal scale: 0 = not present, 1 = little, 2 = intermediate, and 3 = distinct. Data analysis was performed using crosstabs and Visual Grading Characteristics (VGC) analysis.

Results

Overall sensitivity/specificity was calculated with 53.7%/94.4% (T2w-TSE) and 52.8%/95.3% (STIR). VGC revealed an area under the VGC curve of 0.502 (standard error 0.026), P = 0.814.

Conclusion

Perifocal edema is a specific feature of malignancy with moderate sensitivity. VGC analysis did not reveal significant differences between both pulse sequences analysed. Consequently, both T2w-TSE and STIR images are suitable for assessment of perifocal edema.     

MRI of fat necrosis of the breast: the "black hole" sign at short tau inversion recovery

Objective

To describe MRI features of fat necrosis of the breast.

Materials and methods

Twenty-five lesions in 16 patients were retrospectively analyzed. MRI was performed due to equivocal findings at conventional imaging after surgical treatment of cancer (n = 14) or during anticoagulant therapy (n = 1), after focal mastitis treated with ductal resection (n = 1). In the 15 patients with previous surgery MRI was performed after a median interval of 24 months, using short tau inversion recovery (STIR) and contrast-enhanced dynamic T1-weighted sequences. Signal-to-noise ratio (SNR) inside the lesion and surrounding healthy fat was calculated on both STIR and unenhanced T1-weighted images. Maximal lesion diameter was measured on STIR images. All lesions had final clinical and imaging assessment in favor of fat necrosis and negative clinical and imaging follow-up (21–40 months; median 24 months).

Results

At STIR sequence, fat necrosis appeared as a “black hole”, being markedly hypointense (median SNR = 29) compared with surrounding fat (median SNR = 95) (P < 0.001), while no significant difference was found at unenhanced T1-weighted sequence. No significant correlation with time from treatment was found. Of 25 lesions, 15 showed ring enhancement, with continuous increase (n = 10), plateau (n = 2), or wash-out curve (n = 3). The 11 enhancing lesions in the 8 patients with previous radiation therapy showed an initial enhancement higher than that of the 4 enhancing lesions in the 2 patients who did not, although the difference was not significant (P = 0.104).

Conclusion

Fat necrosis of the breast exhibits a “black hole” sign on STIR images, allowing for an easier diagnosis in clinical practice.     

Diffusion-weighted MR imaging findings of kidneys in patients with early phase of obstruction

Background

Diffusion-weighted (DW) magnetic resonance (MR) imaging is an MR technique used to show molecular diffusion. The apparent diffusion coefficient (ADC), as a quantitative parameter calculated from the DW MR images. The purpose of this study is to evaluate the ability of DW MR imaging in early phase of obstruction due to urolithiasis.

Materials and methods

Twenty-six patients with acute dilatation of the pelvicalyceal system detected by intravenous urography were included in this study. MR imaging was performed using a 1.5 T whole-body superconducting MR scanner. DW imaging can be performed using single-shot spin–echo, echo-planar imaging (EPI) sequences with the following diffusion gradient b values: 100, 600, 1000 s/mm². Circular region of interest (ROI) was placed in the renal parenchyma for the measurement of ADC values in the normal and obstructed kidney. For statistical analyses, Paired t test were used.

Results

In spite of obstructed kidneys had the lower ADC values compared to normal kidneys, these alterations were statistically insignificant.

Conclusion

We did not observe significantly different ADC values of early phase of obstructed kidneys compared to normal kidneys.     

Decreased hyperintense vessels on FLAIR images after endovascular recanalization of symptomatic internal carotid artery occlusion

Background and purpose

Hyperintense vessels (HV) on fluid-attenuated inversion recovery (FLAIR) images were assumed to be explained by slow antegrade or retrograde leptomeningeal collateral flow related to extracranial or intracranial artery steno-occlusion. The aim of this study was to investigate the effect of recanalization after endovascular therapy of symptomatic internal carotid artery (ICA) occlusion on the presence of HV.

Methods

Eleven patients with symptomatic ICA occlusion were retrospectively enrolled. Changes in the HV on FLAIR images were examined in affected hemisphere of each patient after successful treatment with endovascular recanalization (angioplasty, n = 3; stent-assisted angioplasty, n = 8). The relationship between postoperative changes in the HV and Thrombolysis In Cerebral Ischemia (TICI) scale (I-III) was assessed.

Results

After operation, HV of the 11 affected hemispheres were showed to be decreased (n = 3) or disappeared (n = 8) in treated side. The median interval between pre- and postoperative MRI examinations was 97.0 h (range, from 69. to 48.7 h). Of the 8 patients with disappeared HV, 7 achieved high TICI grade flow (III) and 1 had relatively low TICI grade flow (IIc) in treated side. However, all the 3 patients with decreased HV were found to be relatively low TICI grade flow (IIc).

Conclusion

Our data indicate that endovascular recanalization of ICA occlusion was effective for decreasing HV. Postoperative decrease in HV can be considered as a marker for hemodynamic improvement.     

Prostate cancer: 1HMRS-DCEMR at 3T versus [(18)F]choline PET/CT in the detection of local prostate cancer recurrence in men with biochemical progression after radical retropubic prostatectomy (RRP)

Objectives

This study compares proton magnetic resonancespectroscopic imaging (1H-MRSI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) combined techniques at 3 T magnet versus [(18)F]choline PET/computed tomography (CT) in the detection of local prostate cancer recurrence in patients with biochemical progression after radical retropubic prostatectomy (RRP).

Materials and methods

84 consecutive patients at high risk of local recurrence underwent combined 1HMRSI-DCEMR and 18-Fcholine- PET/CT. MR scan protocol included turbo spin echo (TSE) T2-weighted sequences in the axial, sagittal and coronal planes; three-dimensional (3D) chemical shift imaging (CSI) sequences with spectral/spatial pulses optimized for quantitative detection of choline and citrate; dynamic contrast enhanced gradient-echo (GRE) T1-weighted sequence.The population was divided into two groups. Group A included 28 patients with a lesion size ranging between 5.00 mm and 7.2 mm and PSA reduction following radiation therapy. Group B included 56 patients with a lesion size between 7.6 mm and 19.4 mm. Sensitivity, specificity, positive predictive value (PPV) and accuracy were evaluated and receiver operating characteristic (ROC) curves were performed.

Results

In Group A combined 1H-MRSI and DCE-MRI showed a sensitivity of 92%, a specificity of 75% (PPV 96%) while PET–CT examination showed a sensitivity of 62% and a specificity of 50% (PPV 88%) in identifying local recurrence. The accuracy of MRI was 89% while PET–CT showed an accuracy of 60%. Areas under the ROC curve (AUC) values for MR and PET–CT were 0.833 and 0.562, respectively. In Group B combined 1H-MRSI and DCEMR showed a sensitivity of 94% and a specificity of 100% (PPV 100%) with accuracy of 94%. PET–CT had a sensitivity of 92% and a specificity of 33% (PPV 98%) with accuracy of 91%. The AUCs for MR and PET–CT values were 0.971 and 0.837, respectively.

Conclusion

The diagnostic accuracy of combined 1HMRSI-DCEMR was higher than PET/CT to identify local prostate cancer recurrence, mostly in patients with low biochemical progression after RRP (0.2–2 ng/mL).     

Imaging manifestation of conventional and contrast-enhanced ultrasonography in percutaneous microwave ablation for the treatment of uterine fibroids

Objectives

To evaluate the image changes and the relationship between conventional ultrasonography and contrast-enhanced ultrasound (CEUS) in the perioperative period of microwave (MW) ablation for uterine fibroids; to guide clinical ablation therapy and evaluate the efficacy of MW.

Methods

Twenty-nine patients with 31 uterine fibroids were recruited in this study. All patients received conventional ultrasound as well as CEUS examination before, immediately after and 12–24 h after MW, in order to detect variations of echo and characteristics of blood supply. t-Tests were used to compare the hyperecho area on gray-scale ultrasound to immediately after ablation non-enhanced CEUS measurements, as well as to compare the immediately after ablation non-enhanced CEUS measurements to the 12–24 h after ablation measurements.

Results

Immediately after ablation, the average hyperecho area in gray-scale was 82.20 ± 72.32 cm³; the average non-enhancement area was 76.34 ± 70.63 cm³ by CEUS, showing a strong correlation (r = 0.997, P < 0.01) to the hyperecho area in gray-scale. The average non-enhancement area measured by CEUS immediately after ablation was 90.55 ± 74.41 cm³ and average 12–24 h after ablation was 98.29 ± 78.25 cm³; no statistically significant difference was detected between the two time points (P > 0.05).

Conclusions

Measurements made by hyperechoic range on gray-scale ultrasonography is strongly correlated to the no enhancement area by CEUS. The hyperechoic range on gray-scale image can represent the ablated area immediately after MW.     

Performance of unenhanced respiratory-gated 3D SSFP MRA to depict hepatic and visceral artery anatomy and variants

Objectives

To prospectively evaluate the performance of unenhanced respiratory-gated magnetization-prepared 3D-SSFP inversion recovery MRA (unenhanced-MRA) to depict hepatic and visceral artery anatomy and variants in comparison to contrast-enhanced dynamic gradient-echo MRI (CE-MRI) and to digital subtraction angiography (DSA).

Methods

Eighty-four patients (55.6 ± 12.4 years) were imaged with CE-MRI (TR/TE 3.5/1.7 ms, TI 1.7 ms, flip-angle 15°) and unenhanced-MRA (TR/TE 4.4/2.2 ms, TI 200 ms, flip-angle 90°). Two independent readers assessed image quality of hepatic and visceral arteries on a 4-point-scale. Vessel contrast was measured by a third reader. In 28 patients arterial anatomy was compared to DSA.

Results

Interobserver agreement regarding image quality was good for CE-MRI (κ = 0.77) and excellent for unenhanced-MRA (κ = 0.83). Unenhanced-MRA yielded diagnostic image quality in 71.6% of all vessels, whereas CE-MRI provided diagnostic image quality in 90.6% (p < 0.001). Vessel-based image quality was significantly superior for all vessels at CE-MRI compared to unenhanced-MRA (p < 0.01). Vessel contrast was similar among both sequences (p = 0.15). Compared to DSA, CE-MRI and unenhanced-MRA yielded equal accuracy of 92.9–96.4% for depiction of hepatic and visceral artery variants (p = 0.93).

Conclusions

Unenhanced-MRA provides diagnostic image quality in 72% of hepatic and visceral arteries with no significant difference in vessel contrast and similar accuracy to CE-MRI for depiction of hepatic and visceral anatomy.     

Clinical usefulness of the visibility of the transcerebral veins at 3T on T2*-weighted sequence in acute stroke patients

Objectives

The objective of this work was to investigate the clinical usefulness of the visibility of the transcerebral veins (VTV) in acute ischemic stroke patients at 3 T.

Methods

Sixty consecutive carotid artery territory stroke patients were included retrospectively. Two readers categorized the VTV on T2*-weighted sequence at 3 T for each hemisphere, and asymmetry of this sign was assessed between each hemisphere by an asymmetry index (AI) using a three-item scale. The VTV and AI were correlated with clinical and radiological covariates. Particular interest was focused on patients for whom initial diffusion-weighted imaging alone was inconclusive.

Results

VTV were detected in the stroke hemisphere in 58.3% (n = 35) and in the contralateral side in 10% (n = 6, p < 0.0001). Asymmetry of the VTV between ischemic and contralateral hemispheres was present in 53.3% (n = 32). Intracranial artery occlusion, final infarct volume and symptomatic hemorrhagic transformation were correlated with a higher AI at baseline (ρ = 0.563, ρ = 0.291, and ρ = 0.285, p < 0.05, respectively). Three hyperacute stroke patients with subtle DWI high signal intensity at admission demonstrated VTV.

Conclusions

The pathological value of the VTV seems to reside in its asymmetry between hemispheres, as it was correlated with important clinical parameters. This study also suggests that the VTV could be a supportive finding in stroke diagnosis, especially when DWI is unreliable.     

Added value of double inversion recovery magnetic resonance sequence in detection of cortical and white matter brain lesions in multiple sclerosis

Objective

The aim of this study was to evaluate the value of double inversion recovery (DIR) magnetic resonance (MR) sequence in the detection of brain cortical and white matter lesions in multiple sclerosis (MS).

Patients and methods

Fifteen patients with remitting relapsing MS were included in this study. Imaging was performed on a 1.T MR system using DIR, fluid-attenuated inversion-recovery (FLAIR), and T2-weighted image (T2WI) sequences. The sensitivity of DIR was compared with the corresponding sensitivity of FLAIR and T2WI sequences. The contrast between lesions and normal-appearing gray matter (NAGM), normal-appearing white matter (NAWM), and cerebrospinal fluid (CSF) was determined for all sequences.

Results

DIR showed significantly more MS lesion load overall when compared to T2WI or FLAIR. Significantly higher number of lesions was seen in the supra- and infratentorial locations. DIR detected higher periventricular white matter lesions when compared to FLAIR, but did not detect significantly higher lesions when compared to T2WI. Significantly higher deep white matter, juxtacortical, and intracortical lesions were seen on DIR when compared to both T2WI and FLAIR. The image contrast measurements between the MS lesions and the NAWM in all anatomical locations were significantly higher in DIR sequence compared to both T2WI and FLAIR sequences. However, there was no significant statistical difference between the DIR and both T2WI and FLAIR sequences regarding the contrast of intracortical lesions compared to NAGM.

Conclusion

DIR sequence is valuable in the imaging workup of MS as it can detect more MS lesions compared to the T2W and FLAIR sequences in all anatomical locations. DIR showed better delineation between the white matter, gray matter, and the MS lesions due to its high image contrast. DIR sequence should be included in the routine MR protocol of MS patients especially to answer the question about intra-cortical and juxta-cortical MS lesions.     

MR-imaging of the thoracic aorta: 3D-ECG- and respiratory-gated bSSFP imaging using the CLAWS algorithm versus contrast-enhanced 3D-MRA

Objective

To compare a contrast-enhanced 3D angiography (CE-3D-MRA) with the ECG- and respiratory gated 3D balanced steady state free precession (bSSFP) sequence using the CLAWS algorithm (3D-bSSFP-CLAWS) with respect to acquisition time, image quality, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR).

Methods

14 patients (4 women, mean age ± SD: 52 ± 18) with known or suspected thoracic aortic disease were imaged on a 1.5 T scanner with both sequences. Two readers scored image quality of predefined levels of the thoracic aorta. Acquisition time, SNR and CNR were calculated for each examination.

Results

Image quality achieved with the 3D-bSSFP-CLAWS was scored significantly better than with the CE-3D-MRA for the aortic annulus (P = 0.003), the sinuses of Valsalva (P = 0.001), the proximal coronary arteries (P = 0.001) and the sinotubular junction (P = 0.001). Effective acquisition time for the 3D-bSSFP-CLAWS and corrected acquisition time (corrected for imaging parameters) was significantly longer compared to the CE-3D-MRA (P = 0.004 and P = 0.028). SNR and CNR were significantly higher for the CE-3D-MRA (P = 0.007 and P = 0.001).

Conclusions

Providing the highest scan efficiency for a given breathing pattern, image quality for the proximal ascending aorta achieved with the 3D-bSSFP-CLAWS is significantly superior in contrast to the CE-3D-MRA.     

Evaluation of carotid vessel wall enhancement with image subtraction after gadobenate dimeglumine-enhanced MR angiography

Objectives

This study was aimed at testing the value of image subtraction for evaluating carotid vessel wall enhancement in contrast-enhanced MR angiography (MRA).

Materials and methods

IRB approval was obtained. The scans of 81 consecutive patients who underwent carotid MRA with 0.1 mmol/kg of gadobenate dimeglumine were reviewed. Axial carotid 3D T1-weighted fast low-angle shot sequence before and 3 min after contrast injection were acquired and subtracted (enhanced minus unenhanced). Vessel wall enhancement was assigned a four-point score using native or subtracted images from 0 (no enhancement) to 3 (strong enhancement). Stenosis degree was graded according to NASCET.

Results

With native images, vessel wall enhancement was detected in 20/81 patients (25%) and in 20/161 carotids (12%), and scored 2.0 ± 0.6 (mean ± standard deviation); with subtracted images, in 21/81 (26%) and 22/161 (14%), and scored 2.5 ± 0.6, respectively (P < 0.001, Sign test). The overall stenosis degree distribution was: mild, 41/161 (25%); moderate, 77/161 (48%); severe, 43/161 (27%). Carotids with moderate stenosis showed vessel wall enhancement with a frequency (17/77, 22%) significantly higher than that observed in carotids with mild stenosis (1/41, 2%) (P = 0.005, Fisher exact test) and higher, even though with borderline significance (P = 0.078, Fisher exact test), than that observed in carotids with severe stenosis (4/43, 9%).

Conclusion

Roughly a quarter of patients undergoing carotid MRA showed vessel wall enhancement. Image subtraction improved vessel wall enhancement conspicuity. Vessel wall enhancement seems to be an event relatively independent from the degree of stenosis. Further studies are warranted to define the relation between vessel wall enhancement and histopathology, inflammatory status, and instability.     

Comparison of 3D turbo spin-echo SPACE sequences with conventional 2D MRI sequences to assess the shoulder joint

Purpose

To determine the accuracy and reliability of three-dimensional (3D) T1- and proton density (PD)-weighted turbo spin-echo (TSE) sampling perfection with application-optimized contrasts using different flip-angle evolution (SPACE) compared with conventional 2D sequences in assessment of the shoulder-joint.

Materials and methods

Ninety-three subjects were examined on a 3-T MRI system with both conventional 2D-TSE sequences in T1-, T2- and PD-weighting and 3D SPACE sequences in T1- and PD-weighting. All examinations were assessed independently by two reviewers for common pathologies of the shoulder-joint. Agreement between 2D- and 3D-sequences and inter-observer-agreement was evaluated using kappa-statistics.

Results

Using conventional 2D TSE sequences as standard of reference, sensitivity, specificity, and accuracy values of 3D SPACE were 81.8%, 95.1%, and 93.5% for injuries of the supraspinatus-tendon (SSP), 81.3%, 93.5%, and 91.4% for the cartilage layer and 82.4%, 98.5%, and 97.5% for the long biceps tendon. Concordance between 2D and 3D was almost perfect for tendinopathies of the SSP (κ = 0.85), osteoarthritis (κ = 1), luxation of the biceps tendon (κ = 1) and adjacent bone marrow (κ = 0.92). Inter-observer-agreement was generally higher for conventional 2D TSE sequences (κ, 0.23–1.0), when compared to 3D SPACE sequences (κ, −0.33 to 1.0) except for disorders of the long biceps tendon and supraspinatus tendon rupture.

Conclusion

Because of substantial and almost perfect concordance with conventional 2D TSE sequences for common shoulder pathologies, MRI examination-time can be reduced by nearly 40% (up to 11 min) using 3D-SPACE without loss of information.     

Higher precontrast CT density of the carotid plaque in the symptomatic patients

Purpose

The purpose of this study was to determine if there is a significant difference in the CT Hounsfield Unit (CTHU) of the carotid atherosclerotic plaque (CAP) on CTpre and CTartery depending on the presence of symptomatology.

Methods

Quantitative analysis of the CTHUs for the CAP was performed in 43 arteries (11 symptomatic arteries, 32 asymptomatic arteries). The CTHUs were measured using the manual ROI method for each CAP. Group differences in the CTHU of the CAP depending on the symptomatology were evaluated by using the independent t-test.

Results

The CTHUs of CAP on CTpre were significantly higher in the symptomatic arteries than those of the asymptomatic arteries (P = 0.036). The CTHUs of CAP on CTartery were not significantly different regardless of symptomatology.

Conclusion

The CTHUs of the CAP on CT_pre may be used as one of the biomarkers to distinguish the vulnerable CAP.     

Evaluation of pancreatic cancer by multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging at 3.0T

Objective

To investigate the microcirculation in pancreatic cancer by pharmacokinetic analysis of multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging at 3.0 T.

Materials and methods

Multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging was performed in 40 healthy volunteers and 40 patients with pancreatic cancer proven by histopathology using an axial three-dimensions fat-saturated T1-weighted spoiled-gradient echo sequence at 3.0 T. A two compartment model with T1 correction was used to quantify the transfer constant, the rate constant of backflux from the extravascular extracellular space to the plasma and the extravascular extracellular space fractional volume in pancreatic cancer, obstructive pancreatitis distal to the malignant tumor, adjacent pancreatic tissue proximal to the tumor and normal pancreas. All parameters were statistically analyzed.

Results

Statistical differences were noticed in both the transfer constant (p = 0.000075) and the rate constant of backflux (p = 0.006) among different tissues. Both the transfer constant and the rate constant of backflux in pancreatic cancer were statistically lower than those in normal pancreas and adjacent pancreatic tissue (p < 0.05). Both the transfer constant and the rate constant of backflux in obstructive pancreatitis were statistically lower than those in normal pancreas and adjacent pancreatic tissue (p < 0.05). The extravascular extracellular space fractional volume in pancreatic cancer was statistically lager than that in normal pancreas (p = 0.002).

Conclusion

Multiple breath-hold dynamic contrast-enhanced magnetic resonance imaging offers a useful technique to evaluate the microenvironment in pancreatic cancer at 3.0 T. Compared to normal pancreas, pancreatic cancer has lower transfer constant, rate constant of backflux and larger extravascular extracellular space fractional volume.     

Indirect MR-arthrography in osteochondral autograft and crushed bone graft with a collagen membrane--correlation with histology

Objective

To analyze the spectrum of findings in indirect MR-arthrography following osteochondral autograft transfer system (OATS) and crushed bone graft using a magnetic resonance imaging (MRI) scoring and grading system in relation to histology as the standard of reference.

Materials and methods

Iatrogenic lesions were set at ovine condylar facets (n = 6/group), treated with OATS or crushed bone graft. 1.5 T MRI was performed 6 months after surgery using PD-weighted (w$w$ fat saturated (fs) fast spin echo (FSE), T1-w 2D, and 3D fs gradient echo (GE) sequences 30 min. after i.v. Gd-DTPA administration and passive joint exercise. The repair tissue was evaluated by two independent radiologists. The MR findings were compared to histology.

Results

In all cases, MRI and histologic grading correlated well and showed significant superior repair in OATS at 6 months (p < 0.05), reproducing the original articular contour and a good subchondral restoration. FsT1-w3DGE proved most appropriate identifying characteristic post-operative findings: the OATS group demonstrated bone marrow edema at the donor site and the graft/host interface showed significant enhancement in indirect MR-arthrography, indicating fibrocartilage. After crushed bone graft, we found an irregular structure and significant contrast uptake, consistent with remnants of bone grafts surrounded by inflammatory tissue.

Conclusion

Indirect MR-arthrography is an accurate, non-invasive monitoring tool following OATS and crushed bone graft as the MRI scoring and grading system allows a reliable evaluation of normal and pathological osteochondral repair with a high histologic correlation.