Detection of hepatocellular carcinoma (HCC) using super paramagnetic iron oxide (SPIO)‐enhanced MRI: Added value of diffusion‐weighted imaging (DWI)

Purpose:

To evaluate whether diffusion‐weighted imaging (DWI) improves the detection of hepatocellular carcinoma (HCC) on super paramagnetic iron oxide (SPIO)‐enhanced MRI.

Materials and Methods:

This retrospective study group consisted of 30 patients with 50 HCC nodules who underwent MRI at 1.5 Tesla. Two combined MR sequence sets were compared for detecting HCC: SPIO‐enhanced MRI (axial T2‐weighted fast spin‐echo (FSE) and T1‐/T2*‐weighted fast field echo (FFE) scanned before and after administration of ferucarbotran) and SPIO‐enhanced MRI + DWI (SPIO‐enhanced MRI with axial DWI scanned before and after administration of ferucarbotran). Three blinded readers independently reviewed for the presence of HCC on a segment‐by‐segment basis using a four‐point confidence scale. The performance of the two combined MR sequence sets was evaluated using receiver operating characteristic (ROC) analysis.

Results:

The average area under the ROC curve (Az) of the three readers for the SPIO‐enhanced MRI + DWI set (0.870 ± 0.046) was significantly higher that that for the SPIO‐enhanced MRI set (0.820 ± 0.055) (P = .025). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of HCC were 66.0%, 98.0%, 90.0%, and 91.4%, respectively, for the SPIO‐enhanced MRI set, and 70.0%, 98.6%, 92.9%, and 92.4%, respectively, for the SPIO‐enhanced MRI + DWI set.

Conclusion:

The SPIO‐enhanced MRI + DWI set outperformed the SPIO‐enhanced MRI set for depicting HCC. J. Magn. Reson. Imaging 2010; 31: 373–382. © 2010 Wiley‐Liss, Inc.     

Multiparametric MRI for prostate cancer localization in correlation to whole‐mount histopathology

Purpose:

To prospectively evaluate multiparametric magnetic resonance imaging (MRI) for accurate localization of intraprostatic tumor nodules, with whole‐mount histopathology as the gold standard.

Materials and Methods:

Seventy‐five patients with biopsy‐proven, intermediate, and high‐risk prostate cancer underwent preoperative T2‐weighted (T2w), dynamic contrast‐enhanced (DCE) and diffusion‐weighted (DW) MRI at 1.5T. Localization of suspicious lesions was recorded for each of 24 standardized regions of interest on the different MR images and correlated with the pathologic findings. Generalized estimating equations (GEE) were used to estimate the sensitivity, specificity, accuracy, positive, and negative predictive value for every MRI modality, as well as to evaluate the influence of Gleason score and pT‐stage. Tumor volume measurements on histopathological specimens were correlated with those on the different MR modalities (Pearson correlation).

Results:

DW MRI had the highest sensitivity for tumor localization (31.1% vs. 27.4% vs. 44.5% for T2w, DCE, and DW MRI, respectively; P < 0.005), with more aggressive or more advanced tumors being more easily detected with this imaging modality. Significantly higher sensitivity values were obtained for the combination of T2w, DCE, and DW MRI (58.8%) as compared to each modality alone or any combination of two modalities (P < 0.0001). Tumor volume can most accurately be assessed by means of DW MRI (r = 0.75; P < 0.0001).

Conclusion:

Combining T2w, DCE, and DW imaging significantly improves prostate cancer localization. J. Magn. Reson. Imaging 2013;37:1392–1401. © 2012 Wiley Periodicals, Inc.     

Washout gradient in dynamic contrast-enhanced MRI is associated with tumor aggressiveness of prostate cancer

Purpose:

To investigate the associations between dynamic contrast‐enhanced magnetic resonance imaging (DCE MRI) parameters and the Gleason score (GS) for prostate cancer (PCA) with localization information provided by concurrent apparent diffusion coefficient (ADC) maps.

Materials and Methods:

Forty‐three male patients received MR scans, including diffusion tensor imaging (DTI) and DCE MRI, on a 1.5 T MR system. All patients were confirmed to have PCA in the following biopsy within 2 weeks. ADC maps calculated from DTI were used to colocalize cancerous and noncancerous regions on DCE MRI for perfusion analysis retrospectively. Semiquantitative parameters (peak enhancement, initial gradient, and washout gradient [WG] and quantitative parameters [K^trans, ν_e, and k_ep]) were calculated and correlated with the GS. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of the perfusion parameters in assessing the aggressiveness of PCA.

Results:

A total of 41 PCA nodules were included in the analysis. Among all quantitative and semiquantitative parameters, only WG showed significant correlation with GS (r = ?0.75, P < 0.0001). By defining tumor aggressiveness as a GS >6, WG demonstrated a good diagnostic performance, with the area under the ROC curve being 0.88. Under a cutoff point of WG = 0.125 min^?1, the sensitivity and specificity were 0.87 and 0.78, respectively.

Conclusion:

WG shows a significant association with GS and good diagnostic performance in assessing tumor aggressiveness. Therefore, WG is a potential marker of GS. J. Magn. Reson. Imaging 2012;36:912–919. © 2012 Wiley Periodicals, Inc.

     

Cisterna chyli in patients with portal hypertension: evaluation with MR imaging

Purpose:

To evaluate the difference in the caliber of cisterna chyli between patients with and without portal hypertension on magnetic resonance imaging (MRI) and to assess the alteration of the caliber of cisterna chyli related to contraction waves during serial T2‐weighted MRI.

Materials and Methods:

This study included 177 patients with and without portal hypertension who underwent two sets of T2‐weighted MRI. MR images were evaluated for the visibility of cisterna chyli, the difference in the diameter of cisterna chyli between two patients groups, and the alteration in the diameter of cisterna chyli during serial T2‐weighted MRI.

Results:

The mean maximal diameter of cisterna chyli in patients with portal hypertension (4.97 ± 1.87 mm, range; 2.5–13.1 mm) was significantly larger (P < 0.001) than that in patients without portal hypertension (3.37 ± 1.25 mm, range; 1.5–6.8 mm). In 132 patients with visible cisterna chyli and portal hypertension, 25 (19%) patients had a positive caliber change of cisterna chyli of more than 2 mm between two sets of T2‐weighted MR images.

Conclusion:

The dilatation of cisterna chyli can be demonstrated at MRI in patients with portal hypertension. Additionally, the positive caliber change of cisterna chyli related to contraction waves was observed in subsets of patients during serial T2‐weighted MRI. J. Magn. Reson. Imaging 2012;35:624‐628. © 2011 Wiley Periodicals, Inc.     

Diffusion-weighted MRI in rectal cancer: apparent diffusion coefficient as a potential noninvasive marker of tumor aggressiveness

Purpose:

To assess the value of diffusion‐weighted MR imaging (DWI) as a potential noninvasive marker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values and MRI and histological prognostic parameters.

Materials and Methods:

Fifty rectal cancer patients underwent primary staging MRI including DWI before surgery and neo‐adjuvant therapy. In 47, surgery was preceded by short‐course radiation therapy (n = 28) or long‐course chemoradiation therapy (n = 19). Mean tumor ADC was measured and compared between subgroups based on pretreatment CEA levels, MRI parameters (mesorectal fascia ‐ MRF ‐ status; T‐stage; N‐stage) and histological parameters (differentiation grade: poorly differentiated, poorly moderately differentiated, moderately differentiated, moderately well differentiated, well‐differentiated; lymphangiovascular invasion).

Results:

Mean tumor ADCs differ between MRF‐free versus MRF‐invaded tumors (P = 0.013), the groups of cN0 versus cN+ cancers (P = 0.011), and between the several groups of histological differentiation grades (P = 0.025). There was no significant difference in mean ADCs between the various groups of CEA levels, the T stage, and the presence of lymphangiovascular invasion.

Conclusion:

Lower ADC values were associated with a more aggressive tumor profile. Significant correlations were found between mean ADC values and radiological MRF status, N stage and differentiation grade. ADC has the potential to become an imaging biomarker of tumor aggressiveness profile. J. Magn. Reson. Imaging 2012;35:1365–1371. © 2012 Wiley Periodicals, Inc.     

Prostate cancer detection with 3 T MRI: Comparison of diffusion‐weighted imaging and dynamic contrast‐enhanced MRI in combination with T2‐weighted imaging

Purpose:

To evaluate the diagnostic ability of diffusion‐weighted imaging (DWI) and dynamic contrast‐enhanced imaging (DCEI) in combination with T2‐weighted imaging (T2WI) for the detection of prostate cancer using 3 T magnetic resonance imaging (MRI) with a phased‐array body coil.

Materials and Methods:

Fifty‐three patients with elevated serum levels of prostate‐specific antigen (PSA) were evaluated by T2WI, DWI, and DCEI prior to needle biopsy. The obtained data from T2WI alone (protocol A), a combination of T2WI and DWI (protocol B), a combination T2WI and DCEI (protocol C), and a combination of T2WI plus DWI and DCEI (protocol D) were subjected to receiver operating characteristic (ROC) curve analysis.

Results:

The sensitivity, specificity, accuracy, and area under the ROC curve (Az) for region‐based analysis were: 61%, 91%, 84%, and 0.8415, respectively, in protocol A; 76%, 94%, 90%, and 0.8931, respectively, in protocol B; 77%, 93%, 89%, and 0.8655, respectively, in protocol C; and 81%, 96%, 92%, and 0.8968, respectively in protocol D. ROC analysis revealed significant differences between protocols A and B (P = 0.0008) and between protocols A and D (P = 0.0004).

Conclusion:

In patients with elevated PSA levels the combination of T2WI, DWI, DCEI using 3 T MRI may be a reasonable approach for the detection of prostate cancer. J. Magn. Reson. Imaging 2010;31:625–631. © 2010 Wiley‐Liss, Inc.     

Prostate cancer detection with multi‐parametric MRI: Logistic regression analysis of quantitative T2, diffusion‐weighted imaging,and dynamic contrast‐enhanced MRI

Purpose

To develop a multi‐parametric model suitable for prospectively identifying prostate cancer in peripheral zone (PZ) using magnetic resonance imaging (MRI).

Materials and Methods

Twenty‐five radical prostatectomy patients (median age, 63 years; range, 44–72 years) had T2‐weighted, diffusion‐weighted imaging (DWI), T2‐mapping, and dynamic contrast‐enhanced (DCE) MRI at 1.5 Tesla (T) with endorectal coil to yield parameters apparent diffusion coefficient (ADC), T2, volume transfer constant (K^trans) and extravascular extracellular volume fraction (v_e). Whole‐mount histology was generated from surgical specimens and PZ tumors delineated. Thirty‐eight tumor outlines, one per tumor, and pathologically normal PZ regions were transferred to MR images. Receiver operating characteristic (ROC) curves were generated using all identified normal and tumor voxels. Step‐wise logistic‐regression modeling was performed, testing changes in deviance for significance. Areas under the ROC curves (A_z) were used to evaluate and compare performance.

Results

The best‐performing single‐parameter was ADC (mean A_z [95% confidence interval]: A_z,ADC: 0.689 [0.675, 0.702]; A_z,T2: 0.673 [0.659, 0.687]; A_z,Ktrans: 0.592 [0.578, 0.606]; A_z,ve: 0.543 [0.528, 0.557]). The optimal multi‐parametric model, LR‐3p, consisted of combining ADC, T2 and K^trans. Mean A_z,LR‐3p was 0.706 [0.692, 0.719], which was significantly higher than A_z,T2, A_z,Ktrans, and A_z,ve (P < 0.002). A_z,LR‐3p tended to be greater than A_z,ADC, however, this result was not statistically significant (P = 0.090).

Conclusion

Using logistic regression, an objective model capable of mapping PZ tumor with reasonable performance can be constructed. J. Magn. Reson. Imaging 2009;30:327–334. © 2009 Wiley‐Liss, Inc.     

Fast Dixon whole-body MRI for detecting distant cancer metastasis: a preliminary clinical study

Purpose:

To evaluate the feasibility of fast Dixon whole‐body (WB) magnetic resonance imaging (MRI) for detecting bone and liver metastasis in clinical patients and to compare its performance with skeletal scintigraphy (SS) for detecting bone metastases using reference imaging with >1 year follow‐up as the gold standard.

Materials and Methods:

Twenty‐nine patients with bone metastases prospectively underwent WB MRI and SS. WB MRI included coronal T2, axial T1 with and without intravenous gadolinium (including triphasic liver sequences), and axial diffusion‐weighted imaging, plus spinal sagittal postcontrast T1‐weighted images. The skeleton was divided into 16 segments. Reviewers blinded to other images identified up to five lesions per segment and rated them using a five‐point confidence scale for metastatic disease. Sensitivities and specificities were compared using the McNemar test.

Results:

The sensitivity of WB MRI and SS in detecting bone metastases was 70.8% and 59.6% (P = 0.003), respectively; specificity was 89.1% and 98.7% (P < 0.0001). WB MRI detected all livers with metastases (n = 8). One focal nodular hyperplasia was classified as a metastasis on WB MRI.

Conclusion:

Fast Dixon WB MRI is feasible in clinical patients, highly specific, and more sensitive than SS in detecting bone metastases, and can detect metastases of the liver. J. Magn. Reson. Imaging 2012;399‐408. © 2011 Wiley Periodicals, Inc.     

Diffusion-weighted MRI as an adjunct to mammography in women under 50 years of age: an initial study

Purpose:

To evaluate diffusion‐weighted magnetic resonance (DW) imaging as an adjunct to mammography for the detection of small invasive breast cancer.

Materials and Methods:

Institutional review board standards were followed for this retrospective study. We performed both breast DW imaging and mammography on 25 women under 50 years of age with pathologically proven T1 breast cancer and on 21 healthy women under 50 years of age. Four offsite radiologists blind to the clinical information independently interpreted the mammograms and DW images and then classified their confidence level regarding the presence of breast cancer. The composite area under receiver operating characteristic curve (AUC), of mammography alone, DW imaging alone, and the combination of DW imaging and mammography (DWI/Cal) were calculated.

Results:

The AUC of composite ROC curves of mammography, DW imaging, DWI/Cal combination, was 0.79 (95% CI, 0.72–0.87), 0.86 (95% CI, 0.84–0.87), and 0.96 (95% CI, 0.92–1.00), respectively.

Conclusion:

DW imaging may be a useful adjunct to mammography in the detection of small invasive breast cancer in women under 50 years of age. J. Magn. Reson. Imaging 2012;36:139–144. © 2012 Wiley Periodicals, Inc.     

MR spectroscopic imaging and diffusion-weighted imaging of prostate cancer with Gleason scores

Purpose:

To investigate functional changes in prostate cancer patients with three pathologically proven different Gleason scores (GS) (3+3, 3+4, and 4+3) using magnetic resonance spectroscopic imaging (MRSI) and diffusion‐weighted imaging (DWI).

Materials and Methods:

In this study MRSI and DWI data were acquired in 41 prostate cancer patients using a 1.5T MRI scanner with a body matrix combined with an endorectal coil. The metabolite ratios of (Cho+Cr)/Cit were calculated from the peak integrals of total choline (Cho), creatine (Cr), and citrate (Cit) in MRSI. Apparent diffusion coefficient (ADC) values were derived from DWI for three groups of Gleason scores. The sensitivity and specificity of MRSI and DWI in patients were calculated using receiver operating characteristic curve (ROC) analysis.

Results:

The mean and standard deviation of (Cho+Cr)/Cit ratios of GS 3+3, GS 3+4, and GS 4+3 were: 0.44 ± 0.02, 0.56 ± 0.06, and 0.88 ± 0.11, respectively. For the DWI, the mean and standard deviation of ADC values in GS 3+3, GS 3+4, and GS 4+3 were: 1.13 ± 0.11, 0.97 ± 0.10, and 0.83 ± 0.08 mm²/sec, respectively. Statistical significances were observed between the GS and metabolite ratio as well as ADC values and GS.

Conclusion:

Combined MRSI and DWI helps identify the presence and the proportion of aggressive cancer (ie, Gleason grade 4) that might not be apparent on biopsy sampling. This information can guide subsequent rebiopsy management, especially for active surveillance programs. J. Magn. Reson. Imaging 2012;36:697–703. © 2012 Wiley Periodicals, Inc.     

Comparison of visceral adipose tissue quantification on water suppressed and nonwater-suppressed MRI at 3.0 Tesla

Purpose:

To systematically evaluate and compare the performance of water‐saturated and nonwater‐saturated T1‐weighted 3.0 T magnetic resonance imaging (MRI) in the application of visceral adipose tissue (VAT) quantification.

Materials and Methods:

Forty‐five patients underwent abdomen MRI using two different sequences at 3.0 T: 1) a traditional T1‐weighted gradient echo sequence, and 2) the same sequence with water presaturation to enhance fat and nonfat contrast. VAT amounts from both water‐saturated and nonwater‐saturated images were quantified with a manual thresholding technique and an automated segmentation method to study quantification variability and consistency of the two imaging techniques.

Results:

Nonwater‐saturated MRI had significantly larger coefficient of variation than water‐saturated MRI in the imaging reproducibility study based on 112 slices from seven subjects (11.4% vs. 2.5%, P < 0.0001). VAT volumes measured from the nonwater‐saturation MRI sequence had significantly higher variability than those from water‐saturation images even when using a manual quantification method based on images from 38 subjects (1.76% vs. 1.08%, P < 0.001). In addition, the VAT volume amounts from nonwater‐saturation images and water‐saturated images quantified with the automatic and manual quantification methods were statistically consistent.

Conclusion:

Water‐saturated MRI sequences at 3.0 T for VAT quantification improve reproducibility and decrease variability compared with nonwater saturated sequences, especially with the use of automatic quantification methods. J. Magn. Reson. Imaging 2012;35:1445–1452. © 2012 Wiley Periodicals, Inc.     

Evaluation of bowel peristalsis by dynamic cine MRI: detection of relevant functional disturbances--initial experience

Purpose:

To investigate the diagnostic performance of a cine magnetic resonance imaging (MRI) sequence in the visualization and detection of impaired bowel peristalsis.

Materials and Methods:

In all, 91 consecutive patients (mean age 45 years) were prospectively examined on a 1.5 T system and stratified into a surgery group (n = 22) and a nonsurgery group (n = 69). A coronal fast imaging with steady‐state precession (TrueFISP) sequence with 30 acquisitions per slice covered the abdomen in 10–15 slices each 7–12 mm thick (temporal resolution: 6–8 sec per frame). Image evaluation for reduced bowel peristalsis and relevant bowel stenosis was compared to surgical findings or clinical follow‐up.

Results:

Cine MRI reached 96% accuracy (94% sensitivity; 100% specificity) in detecting a relevant reduction in bowel peristalsis and 85% of relevant stenosis was identified in the surgery group. Twenty of 69 patients of the nonsurgery group showed reduced peristalsis on cine MR which was attributed to underlying disease; 49/69 patients in this group had no findings on cine MR and were uneventfully followed up.

Conclusion:

Cine MRI of the bowel provides functional information of bowel passage. The visualization of a reduction in peristalsis may improve the assessment of the functional impact of suspected bowel adhesions or stenosis. Standard bowel MR protocols can be easily complemented by cine MR, extending scan time by <4 minutes. J. Magn. Reson. Imaging 2012;35:859–867. © 2012 Wiley Periodicals, Inc.     

Evaluation of the tibial tunnel after intraoperatively administered platelet‐rich plasma gel during anterior cruciate ligament reconstruction using diffusion weighted and dynamic contrast‐enhanced MRI

Purpose:

To evaluate effect of platelet‐rich plasma gel (PRPG), locally administered during the anterior cruciate ligament (ACL) reconstruction, with two MRI methods. The proximal tibial tunnel was assessed with diffusion weighted imaging (DWI) and with dynamic contrast‐enhanced imaging (DCE‐MRI).

Materials and Methods:

In 50 patients, standard arthroscopic ACL reconstructions were performed. The patients in the PRPG group (n = 25) received a local application of PRPG. The proximal tibial tunnel was examined by DWI and DCE‐MRI, which were used to calculate apparent diffusion coefficient (ADC) values, as well as the contrast enhancement gradient (G_enh) and enhancement factor (F_enh) values.

Results:

At 1 month, the calculated average ADC value in the PRPG group was significantly lower than in the control group. At 2.5 and at 6 months, G_enh was significantly higher in the PRPG group. There were no significant differences in F_enh between the groups at any control examination.

Conclusion:

DWI and DCE‐MRI measurements indicate a reduced extent of edema during the first postoperative month as well as an increased vascular density and microvessel permeability in the proximal tibial tunnel at 1 and 2.5 postoperative months as the effect of the application of PRPG. J. Magn. Reson. Imaging 2013;37:928–935. © 2012 Wiley Periodicals, Inc.     

Comparison of 3 Tesla proton MR spectroscopy, MR perfusion and MR diffusion for distinguishing glioma recurrence from posttreatment effects

Purpose:

To compare 3 Tesla (3T) multi‐voxel and single‐voxel proton MR spectroscopy (MRS), dynamic susceptibility contrast perfusion MRI (DSC), and diffusion‐weighted MRI (DWI) for distinguishing recurrent glioma from postradiation injury.

Materials and Methods:

We reviewed all 3T MRS, DSC and DWI studies performed for suspicion of malignant glioma recurrence between October 2006 and December 2008. Maximum Cho/NAA and Cho/Cr peak‐area and peak‐height ratios were recorded for both multi‐voxel and single‐voxel MRS. Maximum cerebral blood volume (CBV) and minimum apparent diffusion coefficient (ADC) were normalized to white matter. Histopathology and clinical‐radiologic follow‐up served as reference standards. Receiver operating characteristic curves for each parameter were compared.

Results:

Forty lesions were classified as glioma recurrence (n = 30) or posttreatment effect (n = 10). Diagnostic performance was similar for CBV ratio (AUC = 0.917, P < 0.001), multi‐voxel Cho/Cr peak‐area (AUC = 0.913, P = 0.002), and multi‐voxel Cho/NAA peak‐height (AUC = 0.913, P = 0.002), while ADC ratio (AUC = 0.726, P = 0.035) did not appear to perform as well. Single‐voxel MRS parameters did not reliably distinguish tumor recurrence from posttreatment effects.

Conclusion:

A 3T DSC and multi‐voxel MRS Cho/Cr peak‐area and Cho/NAA peak‐height appear to outperform DWI for distinguishing glioma recurrence from posttreatment effects. Single‐voxel MRS parameters do not appear to distinguish glioma recurrence from posttreatment effects reliably, and therefore should not be used in place of multi‐voxel MRS. J. Magn. Reson. Imaging 2012;35:56‐63. © 2011 Wiley Periodicals, Inc.     

Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: a feasibility study

Purpose:

To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle.

Materials and Methods:

The MHD effect was scrutinized using a pulsatile flow phantom at B₀ = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B₀ ranging from 0.05–7.0 T. Noncontrast‐enhanced MR angiography (MRA) of the carotids was performed using a gated steady‐state free‐precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization.

Results:

The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B₀ and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B₀ = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG‐triggered MRAs.

Conclusion:

This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle. J. Magn. Reson. Imaging 2012;36:364–372. © 2012 Wiley Periodicals, Inc.     

Diagnostic value of T2‐weighted imaging for the detection of superficial cranial artery inflammation in giant cell arteritis

Purpose:

To evaluate the diagnostic value of T2‐weighted radial MR imaging for the detection of superficial cranial arteries' inflammatory involvement in patients with giant cell arteritis (GCA).

Materials and Methods:

Forty‐three patients with suspected giant cell arteritis underwent 3 Tesla (T) high‐field MRI. T2‐weighted inversion recovery (IR) fast spin echo images with radial sampling (BLADE‐technique) were acquired and compared with postcontrast T1‐weighted spin echo images.

Results:

T2‐weighted images revealed mural edema in the superficial cranial arteries in 11 patients in concordance with severe inflammatory contrast enhancement in T1‐weighted images (grade 4 in a 4‐point ranking scale). Excellent correlation (r = 0.82; P < 0.001) of measured wall thickness in T1‐ and T2‐weighted images was achieved.

Conclusion:

The results of this study indicate the potential of radial T2 weighted imaging for a first detection of inflammatory changes in the small superficial cranial arteries without the need for contrast medium. Future studies are needed to evaluate the influence of spatial resolution of the T2 images and to improve the detection of moderate GCA related changes in vessel inflammation. J. Magn. Reson. Imaging 2010; 31: 470–474. © 2010 Wiley‐Liss, Inc.     

Perfusion fraction of diffusion-weighted MRI for predicting the presence of blood supply in ovarian masses

Purpose:

To evaluate whether perfusion fraction (PF) calculated with diffusion‐weighted magnetic resonance imaging (MRI) predicts the presence of blood supply in ovarian masses.

Materials and Methods:

PFs of 92 ovarian lesions in 53 patients administered gadolinium were retrospectively calculated with diffusion‐weighted images at b‐values of 0, 500, and 1000 sec/mm². PFs were compared between ovarian lesions, except for fat, with (n = 21) or without contrast enhancement (n = 57), using Student's t‐test and receiver operating characteristics (ROC) curve analysis. Lesion enhancement rates of contrast‐enhanced images at 30 and 180 seconds after gadolinium injection (ER_30sec and ER_180sec) and PFs were compared using Pearson's correlation coefficient.

Results:

PFs of the lesions with contrast enhancement were significantly higher than those without contrast enhancement (0.22 ± 0.09 and 0.02 ± 0.08, respectively, P < 0.0001). The ROC curve identified the best cutoff point for PF at 0.135 (95.2% sensitivity and 94.7% specificity) as a predictor of the contrast enhancement effect. The area under the ROC curve was 0.984. PF correlated moderately with ER_30sec (0.62, y = 0.13x + 0.04, P < 0.0001) and ER_180sec (0.74, y = 0.13x + 0.03, P < 0.0001).

Conclusion:

PF calculated with diffusion‐weighted images can potentially predict blood supply in ovarian masses. J. Magn. Reson. Imaging 2011. © 2011 Wiley Periodicals, Inc.     

Diagnosis of cirrhosis with intravoxel incoherent motion diffusion MRI and dynamic contrast‐enhanced MRI alone and in combination: Preliminary experience

Purpose:

To report our preliminary experience with the use of intravoxel incoherent motion (IVIM) diffusion‐weighted magnetic resonance imaging (DW‐MRI) and dynamic contrast‐enhanced (DCE)‐MRI alone and in combination for the diagnosis of liver cirrhosis.

Materials and Methods:

Thirty subjects (16 with noncirrhotic liver, 14 with cirrhosis) were prospectively assessed with IVIM DW‐MRI (n = 27) and DCE‐MRI (n = 20). IVIM parameters included perfusion fraction (PF), pseudodiffusion coefficient (D*), true diffusion coefficient (D), and apparent diffusion coefficient (ADC). Model‐free DCE‐MR parameters included time to peak (TTP), upslope, and initial area under the curve at 60 seconds (IAUC60). A dual input single compartmental perfusion model yielded arterial flow (Fa), portal venous flow (Fp), arterial fraction (ART), mean transit time (MTT), and distribution volume (DV). The diagnostic performances for diagnosis of cirrhosis were evaluated for each modality alone and in combination using logistic regression and receiver operating characteristic analyses. IVIM and DCE‐MR parameters were compared using a generalized estimating equations model.

Results:

PF, D*, D, and ADC values were significantly lower in cirrhosis (P = 0.0056–0.0377), whereas TTP, DV, and MTT were significantly increased in cirrhosis (P = 0.0006–0.0154). There was no correlation between IVIM‐ and DCE‐MRI parameters. The highest Az (areas under the curves) values were observed for ADC (0.808) and TTP‐DV (0.952 for each). The combination of ADC with DV and TTP provided 84.6% sensitivity and 100% specificity for diagnosis of cirrhosis.

Conclusion:

The combination of DW‐MRI and DCE‐MRI provides an accurate diagnosis of cirrhosis. J. Magn. Reson. Imaging 2010;31:589–600. © 2010 Wiley‐Liss, Inc.     

Late stimulation of the sphenopalatine‐ganglion in ischemic rats: Improvement in N‐acetyl‐aspartate levels and diffusion weighted imaging characteristics as seen by MR

Purpose:

To assess, by MR spectroscopy (MRS) and diffusion weighted imaging (DWI), the ability of electrical stimulation of the sphenopalatine ganglion (SPG) to augment stroke recovery in transient middle cerebral artery occluded (t‐MCAO) rats, when treatment is started 18 ± 2 h post‐occlusion.

Materials and Methods:

¹H‐MRS imaging (¹H‐MRSI) and DWI were used to evaluate ischemic brain tissue after SPG stimulation in rats subjected to 2 h of t‐MCAO. Rats were examined by ¹H‐MRSI, DWI, and behavioral tests at 16 ± 2 h, 8 days, and 28 days post‐MCAO.

Results:

N‐Acetyl‐aspartate (NAA) levels of the stimulated and control rats were the same 16 ± 2 h post‐MCAO (0.52 ± 0.03, 0.54 ± 0.03). At 28 days post‐occlusion, NAA levels were significantly higher in the treated group (0.60 ± 0.04) compared with those of the untreated animals (0.50 ± 0.04; P < 0.05). This effect was more pronounced for regions with low NAA values (0.16 ± 0.03) that changed to 0.32 ± 0.03 (P = 0.04) for the treated group and to 0.10 ± 0.03 (P = 0.20) for the controls. DWI data showed better ischemic tissue condition for the treated rats, but the measured parameters showed only a trend of improvement. The MR results were corroborated by behavioral examinations.

Conclusion:

Our findings suggest that SPG stimulation may ameliorate MR tissue characteristics following t‐MCAO even if treatment is started 18 h post‐occlusion. J. Magn. Reson. Imaging 2010;31:1355–1363. © 2010 Wiley‐Liss, Inc.