Intratumoral Susceptibility Signal Research Articles

IDH mutant and 1p/19q co-deleted oligodendrogliomas: tumor grade stratification using diffusion-, susceptibility-, and perfusion-weighted MRI

PurposeCurrently, isocitrate dehydrogenase (IDH) mutation and 1p/19q co-deletion are proven diagnostic biomarkers for both grade II and III oligodendrogliomas (ODs). Non-invasive diffusion-weighted imaging (DWI), susceptibility-weighted imaging (SWI), and dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI) are widely used to provide physiological information (cellularity, hemorrhage, calcifications, and angiogenesis) of neoplastic histology and tumor grade. However, it is unclear whether DWI, SWI, and DSC-PWI are able to stratify grades of IDH-mutant and 1p/19q co-deleted ODs.MethodsWe retrospectively reviewed the conventional MRI (cMRI), DWI, SWI, and DSC-PWI obtained on 33 patients with IDH-mutated and 1p/19q co-deleted ODs. Features of cMRI, normalized ADC (nADC), intratumoral susceptibility signals (ITSSs), normalized maxim CBV (nCBV), and normalized maximum CBF (nCBF) were compared between low-grade ODs (LGOs) and high-grade ODs (HGOs). Receiver operating characteristic curve and logistic regression were applied to determine diagnostic performances.ResultsHGOs tended to present with prominent edema and enhancement. nADC, ITSSs, nCBV, and nCBF were significantly different between groups (all P < 0.05). The combination of SWI and DSC-PWI for grading resulted in sensitivity and specificity of 100.00 and 93.33%, respectively.ConclusionsIDH-mutant and 1p/19q co-deleted ODs can be stratified by grades using cMRI and advanced magnetic resonance imaging techniques including DWI, SWI, and DSC-PWI. Combined ITSSs with nCBV appear to be a promising option for grading molecularly defined ODs in clinical practice.

Use of Ultrasmall Superparamagnetic Iron Oxide Enhanced Susceptibility Weighted Imaging and Mean Vessel Density Imaging to Monitor Antiangiogenic Effects of Sorafenib on Experimental Hepatocellular Carcinoma.

We investigated effectiveness of ultrasmall superparamagnetic iron oxide enhanced susceptibility weighted imaging (USPIO-enhanced SWI) and mean vessel density imaging (Q) in monitoring antiangiogenic effects of Sorafenib on orthotopic hepatocellular carcinoma (HCC). Thirty-five HCC xenografts were established. USPIO-enhanced SWI and Q were performed on a 1.5 T MR scanner at baseline, 7, 14, and 21 days after Sorafenib treatment. Intratumoral susceptibility signal intensity (ITSS) and Q were serially measured and compared between the treated (n = 15) and control groups (n = 15). Both ITSS and Q were significantly lower in the treated group at each time point (P < 0.05). Measurements in the treated group showed that ITSS persisted at 7 days (P = 0.669) and increased at 14 and 21 days (P < 0.05), while Q significantly declined at 7 days (P = 0.028) and gradually increased at 14 and 21 days. In the treated group, significant correlation was found between Q and histologic microvessel density (MVD) (r = 0.753, P < 0.001), and ITSS correlated well with MVD (r = 0.742, P = 0.002) after excluding the data from baseline. This study demonstrated that USPIO-enhanced SWI and Q could provide novel biomarkers for evaluating antiangiogenic effects of Sorafenib on HCC.

Susceptibility-Weighted Imaging of Glioma: Update on Current Imaging Status and Future Directions.

Susceptibility-weighted imaging (SWI) provides invaluable insight into glioma pathophysiology and internal tumoral architecture. The physical contribution of intratumoral susceptibility signal (ITSS) may correspond to intralesional hemorrhage, calcification, or tumoral neovascularity. In this review, we present emerging evidence of ITSS for assessment of intratumoral calcification, grading of glioma, and factors influencing the pattern of ITSS in glioblastoma. SWI phase imaging assists in identification of intratumoral calcification that aids in narrowing the differential diagnosis. Development of intratumoral calcification posttreatment of glioma serves as an imaging marker of positive therapy response. Grading of tumors with ITSS using information attributed to microhemorrhage and neovascularity in SWI correlates with MR perfusion parameters and histologic grading of glioma and enriches preoperative prognosis. Quantitative susceptibility mapping may provide a means to discriminate subtle calcifications and hemorrhage in tumor imaging. Recent data suggest ITSS patterns in glioblastoma vary depending on tumoral volume and sublocation and correlate with degree of intratumoral necrosis and neovascularity. Increasingly, there is a recognized role of obtaining contrast-enhanced SWI (CE-SWI) for assessment of tumoral margin in high-grade glioma. Significant higher concentration of gadolinium accumulates at the border of the tumoral invasion zone as seen on the SWI sequence; this results from contrast-induced phase shift that clearly delineates the tumor margin. Lastly, absence of ITSS may aid in differentiation between high-grade glioma and primary CNS lymphoma, which typically shows absence of ITSS. We conclude that SWI and CE-SWI are indispensable tools for diagnosis, preoperative grading, posttherapy surveillance, and assessment of glioma.

Contrast-enhanced susceptibility weighted imaging with ultrasmall superparamagnetic iron oxide improves the detection of tumor vascularity in a hepatocellular carcinoma nude mouse model.

To evaluate the effectiveness of contrast-enhanced susceptibility-weighted imaging with ultrasmall superparamagnetic iron oxide (USPIO-enhanced SWI) in the assessment of intratumoral vascularity in hepatocellular carcinoma (HCC). Orthotopic xenograft HCC nude mouse models were established first and magnetic resonance imaging (MRI) examinations were performed on a 1.5T MR scanner 28 days later. Three groups of mice, 10 in each, were imaged using unenhanced and USPIO-enhanced SWI at doses of 4, 8, and 12 mg Fe/kg. Intratumoral susceptibility signal intensity (ITSS) was scored. ITSS-to-tumor contrast-to-noise ratio (ITSST-CNR) was measured. These measurements were compared between unenhanced and USPIO-enhanced SWI at each dose and differences in the measurements between different dose groups were estimated. Correlation between ITSS and tumor microvessel density (MVD) was analyzed. Compared with unenhanced SWI, significantly higher ITSS was identified on USPIO-enhanced SWI at doses of 8 mg Fe/kg (Z = -2.000, P = 0.046) and 12 mg Fe/kg (Z = -2.333, P = 0.020). Significantly higher ITSST-CNR was found on USPIO-enhanced SWI than that on unenhanced SWI (P < 0.05). Significantly higher ITSST-CNR at a dose of 8 mg Fe/kg was observed than that at 4 mg Fe/kg (Z = -3.326, P = 0.001). Positive correlation between ITSS on USPIO-enhanced SWI at a dose of 8 mg Fe/kg and tumor MVD was demonstrated (r = 0.817, P = 0.004). USPIO-enhanced SWI at a dose of 8 mg Fe/kg greatly improves the detection of intratumoral vascularity in a xenograft HCC model. J. Magn. Reson. Imaging 2016;44:288-295.

Susceptibility-weighted imaging and diffusion-weighted imaging findings in central nervous system monomorphic B cell post-transplant lymphoproliferative disorder before and after treatment and comparison with primary B cell central nervous system lymphoma.

The purpose of this article is to review the MRI features of monomorphic central nervous system post-transplant lymphoproliferative disorder (CNS PTLD), including diffusion-weighted and susceptibility-weighted sequences before and after treatment and to compare the imaging findings with those of primary central nervous system B cell lymphoma (PCNS BCL). Retrospective review of the brain MRI characteristics in patients with pathology proven monomorphic CNS PTLD and PCNS BCL was performed. In particular, the enhancement, diffusion-weighted, susceptibility-weighted MRI characteristics of the lesions were evaluated. In addition, the diffusion-weighted, susceptibility-weighted MRI features after treatment for CNS PTLD were evaluated. A total of 12 lesions in six patients with CNS PTLD and 12 lesions in nine patients with PCNS BCL were identified on MRI. Among the CNS PTLD lesions with post-contrast images, 80 % demonstrated peripheral enhancement. All of the CNS PTLD lesions contained foci of intratumoral susceptibility signal (ITSS) and the average mean ADC values and ratios were 0.892 × 10(-3) mm(2)/s (standard deviation: 0.082 × 10(-3) mm(2)/s) and 1.19 (standard deviation: 0.15), respectively. On the other hand, 75 % of the PCNS BCL displayed diffuse enhancement, two cases (16.7 %) contained ITSS, and the mean ADC values and ratios were 0.721 × 10(-3) mm(2)/s (standard deviation: 0.093 × 10(-3) mm(2)/s), and 0.99 (standard deviation: 0.17), respectively. Thus, the presence of heterogeneous lesions with ITSS that do not necessarily have as extensive restricted diffusion as PCNS BCL is suggestive of CNS PTLD in the appropriate clinical setting. The preliminary data in this series suggests that diffusion-weighted imaging may serve as a useful biomarker for monitoring treatment response, in which successful treatment of CNS PTLD may result in increased ADC values. In addition, foci of susceptibility effect in CNS PTLD tend to persist or increase over the course of treatment.

Primary central nervous system lymphoma: is absence of intratumoral hemorrhage a characteristic finding on MRI?

Background.Previous studies have shown that intratumoral hemorrhage is a common finding in glioblastoma multi-forme, but is rarely observed in primary central nervous system lymphoma. Our aim was to reevaluate whether intratumoral hemorrhage observed on T2-weighted imaging (T2WI) as gross intratumoral hemorrhage and on susceptibility-weighted imaging as intratumoral susceptibility signal can differentiate primary central nervous system lymphoma from glioblastoma multiforme.Patients and methods.A retrospective cohort of brain tumors from August 2008 to March 2013 was searched, and 58 patients (19 with primary central nervous system lymphoma, 39 with glioblastoma multiforme) satisfied the inclusion criteria. Absence of gross intratumoral hemorrhage was examined on T2WI, and an intratumoral susceptibility signal was graded using a 3-point scale on susceptibility-weighted imaging. Results were compared between primary central nervous system lymphoma and glioblastoma multiforme, and values of P < 0.05 were considered significant.Results.Gross intratumoral hemorrhage on T2WI was absent in 15 patients (79%) with primary central nervous system lymphoma and 23 patients (59%) with glioblastoma multiforme. Absence of gross intratumoral hemorrhage could not differentiate between the two disorders (P = 0.20). However, intratumoral susceptibility signal grade 1 or 2 was diagnostic of primary central nervous system lymphoma with 78.9% sensitivity and 66.7% specificity (P < 0.001), irrespective of gross intratumoral hemorrhage.Conclusions.Low intratumoral susceptibility signal grades can differentiate primary central nervous system lymphoma from glioblastoma multiforme. However, specificity in this study was relatively low, and primary central nervous system lymphoma cannot be excluded based solely on the presence of an intratumoral susceptibility signal.

Glioma grading by microvascular permeability parameters derived from dynamic contrast-enhanced MRI and intratumoral susceptibility signal on susceptibility weighted imaging.

BackgroundDynamic contrast-enhanced MRI (DCE-MRI) estimates vascular permeability of brain tumors, and susceptibility-weighted imaging (SWI) may demonstrate tumor vascularity by intratumoral susceptibility signals (ITSS). This study assessed volume transfer constant (Ktrans) accuracy, the volume of extravascular extracellular space (EES) per unit volume of tissue (Ve) derived from DCE-MRI, and the degree of ITSS in glioma grading.MethodsThirty-two patients with different glioma grades were enrolled in this retrospective study. Patients underwent DCE-MRI and non-contrast enhanced SWI by three-tesla scanning. Ktrans values, Ve, and the degree of ITSS in glioma were compared. Receiver operating characteristic (ROC) curve analysis determined diagnostic performances of Ktrans and Ve in glioma grading, and Spearman’s correlation analysis determined the associations between Ktrans, Ve, ITSS, and tumor grade.ResultsKtrans and Ve values were significantly different between low grade gliomas (LGGs) and both high grade gliomas (HGGs) and grade II, III and IV gliomas (P < 0.01). The degree of ITSS of LGGs was lower than HGGs (P < 0.01), and the ITSS of grade II gliomas was lower than grade III or IV gliomas. Ktrans and Ve were correlated with glioma grade (P < 0.01), while ITSS was moderately correlated (P < 0.01). Ktrans values were moderately correlated with ITSS in the same segments (P < 0.01).ConclusionKtrans and Ve values, and ITSS helped distinguish the differences between LGGs and HGGs and between grade II, III and IV gliomas. There was a moderate correlation between Ktrans and ITSS in the same tumor segments.

Variations of ITSS-Morphology and their Relationship to Location and Tumor Volume in Patients with Glioblastoma.

Susceptibility weighted imaging and assessment of intratumoral susceptibility signal (ITSS) morphology is used to identify high-grade glioma (HGG) in patients with suspected brain neoplasm. The aim of this study was to outline variations in ITSS-morphology and their relationship to location as well as volume of the lesion in patients with glioblastoma (GB). Contrast-enhanced SWI (CE-SWI) images of 40 patients with histologically confirmed GB were analyzed retrospectively with particular attention to ITSS-morphology dividing all lesions into two groups. Considering the location of the lesion within brain parenchyma, lesions with and without involvement of the subventricular zone (SVZ+/SVZ-) were discerned. Additionally, the contrast-enhancing tumor volume was evaluated. Statistical analysis was based on a classification analysis resulting in a classification rule (tree) as well as Mann-Whitney-U test. The distribution of ITSS-scores showed differences between the SVZ+ and SVZ- groups. While SVZ-GB showed only fine-linear or dot-like ITSS, in SVZ+ GB the ITSS-morphology changed with the tumor volume, that is, in larger tumors dense and conglomerated ITSS were the predominant finding. Our findings indicate that ITSS-morphology is not a random phenomenon. Location of GB, as well as tumor volume, appear to be factors contributing to ITSS morphology.

Cerebral MR imaging of malignant melanoma

Melanoma is the third leading cancer entity to metastasize to the central nervous system (CNS) after lung and breast cancer. This is often an early event in the disease course and limits survival. Metastasis in the CNS is the cause of death in 10-40 % of melanoma patients and the incidence of brain metastasis is even higher (50-75 %). Cerebral metastases are commonly found in the subcortical white matter. The signal characteristics can vary substantially and may change over time due to hemorrhages or the accumulation of melanin and paramagnetic ions. It is not yet clear whether novel targeted therapies (e.g. immunotherapy and kinase inhibitors) alter imaging characteristics. Also immune-related side effects, such as hypophysitis (in approximately 5 % of patients receiving ipilimumab therapy) or granulomatous disease (neurosarcoid) can occur. Melanoma metastases are usually hyperdense in computed tomography (CT). In magnetic resonance imaging (MRI) T2-weighted (T2-w) fluid-attentuated inversion recovery (FLAIR) and T1-w sequences (with and without i.v. contrast) should be obtained. Coronal and axial imaging planes should be scanned to cross-correlate findings. Susceptibility-weighted imaging is a new sensitive method to detect melanoma metastases. Approximately 66 % of melanoma metastases show intratumoral susceptibility signals (ITSS). This sets them apart from other metastases (e.g. lung and breast cancer show less ITSSs, specificity approximately 81-96 %). Diffusion imaging plays no major role in melanoma brain imaging. Susceptibility-weighted imaging increases the sensitivity to detect metastases but lacks specificity. Differentiating metastases, microbleeding or calcification can be impossible. It is controversial how to interpret susceptibility signals without correlative signs on other sequences (differential diagnosis: metastasis, microbleeding and calcification). CNS metastases are common in melanoma. MRI screening starting in stage IIc should be considered even in asymptomatic patients. Stage IV requires quarterly MRI examinations. Melanotic and amelanotic metastases show different MRI characteristics. The differentiation between metastasis and microbleeding can be impossible and might require a follow-up scan. Susceptibility-weighted imaging increases the sensitivity of metastases detection but lacks specificity. It can help to differentiate between different metastatic entities.

Primary central nervous system lymphoma and atypical glioblastoma: multiparametric differentiation by using diffusion-, perfusion-, and susceptibility-weighted MR imaging.

To compare multiparametric diagnostic performance with diffusion-weighted, dynamic susceptibility-weighted contrast material-enhanced perfusion-weighted, and susceptibility-weighted magnetic resonance (MR) imaging for differentiating primary central nervous system lymphoma (PCNSL) and atypical glioblastoma. This retrospective study was institutional review board-approved and informed consent was waived. Pretreatment MR imaging was performed in 314 patients with glioblastoma, and a subset of 28 patients with glioblastoma of atypical appearance (solid enhancement with no visible necrosis) was selected. Parameters of diffusion-weighted (apparent diffusion coefficient [ADC]), susceptibility-weighted (intratumoral susceptibility signals [ITSS]), and dynamic susceptibility-weighted contrast-enhanced perfusion-weighted (relative cerebral blood volume [rCBV]) imaging were evaluated in these 28 patients with glioblastoma and 19 immunocompetent patients with PCNSL. A two-sample t test and χ(2) test were used to compare parameters.The diagnostic performance for differentiating PCNSL from glioblastoma was evaluated by using logistic regression analyses with leave-one-out cross validation. Minimum, maximum, and mean ADCs and maximum and mean rCBVs were significantly lower in patients with PCNSL than in those with glioblastoma (P < .01, respectively), whereas mean ADCs and mean rCBVs allowed the best diagnostic performance. Presence of ITSS was significantly lower in patients with PCNSL (32% [six of 19]) than in those with glioblastoma (82% [23 of 28]) (P < .01). Multiparametric assessment of mean ADC, mean rCBV, and presence of ITSS significantly increased the probability for differentiating PCNSL and atypical glioblastoma compared with the evaluation of one or two imaging parameters (P < .01), thereby correctly predicting histologic results in 95% (18 of 19) of patients with PCNSL and 96% (27 of 28) of patients with atypical glioblastoma. Combined evaluation of mean ADC, mean rCBV, and presence of ITSS allowed reliable differentiation of PCNSL and atypical glioblastoma in most patients, and these results support an integration of advanced MR imaging techniques for the routine diagnostic workup of patients with these tumors.

Prediction of nuclear grade of clear cell renal cell carcinoma with MRI: intratumoral susceptibility signal intensity versus necrosis

End-stage renal disease and dialysis patients have a higher incidence of renal cell carcinoma (RCC) than the general population. Preoperatively evaluating the biological behavior of RCC plays an important role in treatment decision-making. Susceptibility-weighted imaging (SWI) can visualize the distribution of microvenous structures and hemorrhage without contrast materials. To evaluate the feasibility of SWI in grading clear cell RCCs (CRCC) and compare the ability of SWI and necrosis for grading CRCCs. Retrospective reviews of 35 patients with pathologically-proven CRCCs were performed. All patients underwent both conventional magnetic resonance imaging (MRI) and SWI examinations. The morphology of the intratumoral susceptibility signal intensities (ITSS) was classified into hemorrhage and microvessels. The differences of ITSSs on SWI and necrosis between low- and high-grade CRCCs were assessed. The diagnostic values of ITSSs and necrosis in differentiating low- from high-grade CRCCs were compared by receiver-operating characteristics. ITSSs were seen in 31 of 35 patients. No ITSSs were seen in four patients with low-grade CRCCs. Mean scores of ITSSs on SWI were significantly lower for low-grade CRCCs (1.24 ± 0.72) than that for the high-grade CRCCs (2.70 ± 0.48). No significant necrosis was seen in 10 patients with low-grade CRCCs. There was a significant difference of the presence of intratumoral necrosis between low- and high-grade CRCCs. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were for ITSSs: 70%, 100%, 100%, and 89.3%, respectively; for necrosis: 100%, 40%, 40%, and 100%. SWI can evaluate ITSSs without contrast materials and can be an alternative to grading CRCCs preoperatively for some special patients.

Non-invasive assessment of intratumoral vascularity using arterial spin labeling: A comparison to susceptibility-weighted imaging for the differentiation of primary cerebral lymphoma and glioblastoma

Using conventional MRI methods, the differentiation of primary cerebral lymphomas (PCNSL) and other primary brain tumors, such as glioblastomas, is difficult due to overlapping imaging characteristics.This study was designed to discriminate tumor entities using normalized vascular intratumoral signal intensity values (nVITS) obtained from pulsed arterial spin labeling (PASL), combined with intratumoral susceptibility signals (ITSS) from susceptibility-weighted imaging (SWI).Thirty consecutive patients with glioblastoma (n=22) and PCNSL (n=8), histologically classified according to the WHO brain tumor classification, were included. MRIs were acquired on a 3T scanner, and included PASL and SWI sequences. nVITS was defined by the signal intensity ratio between the tumor and the contralateral normal brain tissue, as obtained by PASL images. ITSS was determined as intratumoral low signal intensity structures detected on SWI sequences and were divided into four different grades.Potential differences in the nVITS and ITSS between glioblastomas and PCNSLs were revealed using statistical testing. To determine sensitivity, specificity, and diagnostic accuracy, as well as an optimum cut-off value for the differentiation of PCNSL and glioblastoma, a receiver operating characteristic analysis was used.We found that nVITS (p=0.011) and ITSS (p=0.001) values were significantly higher in glioblastoma than in PCNSL. The optimal cut-off value for nVITS was 1.41 and 1.5 for ITSS, with a sensitivity, specificity, and accuracy of more than 95%. These findings indicate that nVITS values have a comparable diagnostic accuracy to ITSS values in differentiating glioblastoma and PCNSL, offering a completely non-invasive and fast assessment of tumoral vascularity in a clinical setting.

Detection of Intratumoral Susceptibility Signals Using T2*-Weighted Gradient Echo MRI in Patients with Clear Cell Renal Cell Carcinoma

ObjectiveTo retrospectively evaluate whether T2*-weighted imaging can be used to grade clear cell renal cell carcinomas (ccRCC) based on intratumoral susceptibility signals (ISSs).Materials and MethodsMR imaging from 37 patients with pathologically-proven ccRCCs was evaluated. ISSs on T2*WI were classified as linear or conglomerated linear structures (type I) and dot-like or patchy foci (type II). Two radiologists assessed the likelihood of the presence of ISS, dominant structure of ISS and ratio of ISS area to tumor area. Results were analyzed by nonparametric Mann-Whitney test.ResultsISSs were seen in all patients except for four patients with low-grade ccRCCs and two patients with high-grade ccRCCs. There was no significant difference of the likelihood of the presence of ISS between low- and high-grade ccRCCs. More type I ISSs and less type II ISSs were predictive of low-grade tumors, whereas more conspicuity type II ISSs correlated with higher occurrence of high-grade tumors (P<0.05). The ratio of ISS area to tumor area was also significantly higher for the high-grade group (1.27±0.79) than that for the low-grade group (0.81±0.40) (P<0.05).ConclusionISSs on T2*-weighted gradient-echo MR images can help grade ccRCCs before operations.

Combined value of susceptibility-weighted and perfusion-weighted imaging in assessing who grade for brain astrocytomas.

To assess the value of combining susceptibility-weighted imaging (SWI) and dynamic susceptibility weighted contrast-enhanced (DSC) perfusion-weighted MRI (PWI) in assessing World Health Organization (WHO)grade for brain astrocytoma . A total of 94 patients with pathologically confirmed astrocytomas underwent SWI and DSC scans. The evaluation included intratumoral susceptibility signal intensity (ITSS) and relative cerebral blood volume (rCBV) max. The receiver operating characteristic curve (ROC) was used to assess the efficacy of combining two sequences in astrocytoma grading. ITSS within astrocytomas showed significant correlations with rCBV max (r ¼ 0.72; P < 0.01) and with tumor grades (r ¼ 0.92; P < 0.01), and there was also a significant correlation between rCBV and tumor grade (r= 0.77; P < 0.001). The area under the ROC, SWI, PWI,SWI, and PWI, in differentiation of the grades II and III astrocytomas were 0.995, 0.942, and 1.000, respectively;identifying grades III and IV were 0.773, 0.919, and 0.978, respectively; and identifying high and low-grade astrocytomas were 0.999, 0.992, 1.000, respectively. ITSS was useful for assessing the WHO tumor grade in this cohort of patients with astrocytoma.The combination of SWI and PWI may improve the diagnostic accuracy of astrocytoma grading.

Benefits of contrast-enhanced SWI in patients with glioblastoma multiforme

SWI can help to identify high-grade gliomas (HGG). The objective of this study was to analyse SWI and CE-SWI characteristics, i.e. the relationship between contrast-induced phase shifts (CIPS) and intratumoral susceptibility signals (ITSS) and their association with tumour volume in patients with glioblastoma multiforme (GBM). MRI studies of 29 patients were performed to evaluate distinct susceptibility signals comparing SWI and CE-SWI characteristics. The relationship between these susceptibility signals and CE-T1w tumour volume was analysed by using Spearman's rank correlation coefficient and Kruskal-Wallis-test. Tumour biopsies of different susceptibility signals were performed in one patient. Comparison of SWI and CE-SWI demonstrated different susceptibility signals. Susceptibility signals visible on SWI images are consistent with ITSS; those only seen on CE-SWI were identified as CIPS. Correlation with CE-T1w tumour volume revealed that CIPS were especially present in small or medium-sized GBM (Spearman's rho r = 0.843, P < 0.001). Histology identified the area with CIPS as the tumour invasion zone, while the area with ITSS represented micro-haemorrhage, highly pathological vessels and necrosis. CE-SWI adds information to the evaluation of GBM before therapy. It might have the potential to non-invasively identify the tumour invasion zone as demonstrated by biopsies in one case. • MRI is used to help differentiate between low- and high-grade gliomas. • Contrast-enhanced susceptibility-weighted MRI (CE-SWI) helps to identify patients with glioblastoma multiforme. • CE-SWI delineates the susceptibility signal (CIPS and ITSS) more than the native SWI. • CE-SWI might have the potential to non-invasively identify the tumour invasion zone.

Assessment of Intratumoral Micromorphology for Patients with Clear Cell Renal Cell Carcinoma Using Susceptibility-Weighted Imaging

BackgroundMultiple treatment options exist for the management of renal cell carcinomas. Preoperative evaluation of clear cell renal cell carcinoma (CRCC) grades is important for deciding upon the appropriate method of therapy. We hypothesize that susceptibility weighted imaging (SWI) is sensitive enough to detect intratumoral microvessles and microbleeding in renal cell carcinoma, which can be used to grade CRCC.Material and MethodsRetrospective reviews of 37 patients with pathologically proven CRCCs were evaluated. All patients underwent SWI examinations. The characteristics of intratumoral susceptibility signal intensity (ITSS) includes the likelihood of the presence of ITSS, morphology of ITSS, dominant structure of ITSS and ratio of ITSS area to tumor area, which were all assessed on SWI. The results were compared using the nonparametric Mann-Whitney test.ResultsITSS was seen in all patients except 4 patients with low-grade CRCCs. There was no significant difference between low and high-grade CRCCs when looking at the likelihood of the presence of ITSS. There was a significant difference in the mean score of dominant structures between low and high-grade CRCCs. Specifically, more dominant vascular structures and less hemorrhage were seen in low-grade tumors (2.15±1.05) compared to high-grade tumors (1.27±0.47) (P<0.005). The ratio of ITSS area to tumor area was also significantly higher for the high-grade group (1.55±0.52) than that for the low-grade group (0.88±0.43) on SWI (P<0.005).ConclusionSWI is useful for grading CRCCs.

Combined value of susceptibility weighted imaging and dynamic susceptibility-weighted contrast-enhanced MR perfusion-weighted imaging in brain astrocytoma grading

Objective To assess the value of combination of susceptibility weighted imaging (SWI)and dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion-weighted magnetic resonance imaging in astrocytoma grading.Methods SWI and DSC scans were performed in 82 patients with pathologically confirmed astrocytoma.The patient group consisted of grade Ⅱ (15),grade Ⅲ (10),and grade Ⅳ (57).The intratumoral susceptibility signal intensity (ITSS) and relative cerebral blood volume (rCBV) max were used to determine the grade of astrocytomas by Kruskal Wallis test,Welch test,Spearman correlation coefficients,Pearson correlation coefficients,and receiver operating characteristic curve (ROC)statistic methods.Results There were no ITSS in 14 cases of low-grade astrocytomas,the degree of ITSS were grade 1 to 3 in anaplastic astrocytomas,the degree of ITSS were grade 3 in all of the glioblastomas,the degree of ITSS were significant difference in all grades (H =71.96,P ＜ 0.01).rCBV max in grade Ⅱ,grade Ⅲ and grade Ⅳ astrocytomas were 1.26 ± 0.42,3.59 ± 2.09 and 8.34 ± 1.16 respectively,rCBV max were significant difference in all grades (F' =681.72,P ＜ 0.01).ITSS showed significant correlation with rCBV max (r =0.72,P ＜0.01) and tumor grades (r =0.89,P ＜0.01),and rCBV and tumor grades showed significant correlation (r =0.78,P ＜ 0.01).Area under the ROC curve application SWI,DSC,SWI and DSC in differentiation of the grade Ⅱ and grade Ⅲ astrocytomas were 0.99,0.93,1.00,differentiate grade Ⅲ from grade Ⅳ were 0.70,0.94,0.94,and differentiate high-grade from low-grade astrocytomas were 1.00,0.99,1.00.Conclusions ITSS is helpful to determine the grade of astrocytomas.The use of SWI in combination with DSC may improve the diagnostic accuracy of astrocytoma grading. Key words: Astrocytoma; Magnetic resonance imaging; Perfusion ; Diagnosis, differential

Differentiation of brain metastases by percentagewise quantification of intratumoral-susceptibility-signals at 3 Tesla

IntroductionEvaluation of intratumoral-susceptibility-signals (ITSS) in susceptibility-weighted-imaging (SWI) has been reported to improve diagnostic performance for solitary enhancing brain lesions. Due to the distinct morphologic variability of ITSS, standardized evaluation proved to be difficult. We analyzed, if a new postprocessing method using percentagewise quantification (PQ) of ITSS enables differentiation between different entities of cerebral metastases and may thus improve differential diagnosis in cases of unknown primary. Materials and methodsSWI and contrast enhanced T1-weighted MR images were acquired from 84 patients with intracerebral metastases (20 patients with mamma carcinoma (MC), 15 patients with malignant melanoma (MM), 49 patients with bronchial carcinoma (BC)) at 3Tesla MR. Images were co-registered and enhancing lesions were delineated on T1-weighted images and the outline transferred to the corresponding SWI map. All voxels within the lesion presenting values below a reference value placed in the ventricular system were determined and percentagewise calculated. ResultsDiagnostic performance of percentagewise quantification (PQ) of ITSS, as determined with area under the receiver operating characteristic curve (AUC) was excellent (AUC=0.96; 95% confidence interval (CI) 0.90, 1.00) to discriminate MM from MC, good for the discrimination of MM and BC (AUC=0.81, 95% CI 0.70, 0.92) and poor for the discrimination of MC and BC (AUC=0.60; 95% CI 0.47, 0.73). ConclusionPQ is a new approach for the assessment of SWI that can be used for differential diagnosis of intracerebral metastases. Metastases of MM and MC or BC can be distinguished with high sensitivity and specificity.

Glioblastomas vs. Lymphomas: More Diagnostic Certainty by Using Susceptibility-Weighted Imaging (SWI)

It can be difficult to differentiate glioblastomas from lymphomas using only standard MR images. There are references suggesting that it might be possible to differentiate these tumors using susceptibility-weighted imaging (SWI). The purpose of this study is to prove the diagnostic benefit using susceptibility-weighted images. Three neuroradiologists tried to differentiate 4 histologically verified lymphomas from 11 glioblastomas in retrospect. They first viewed the conventional MR images and declared a diagnosis with a grade of certainty. Afterwards they additionally reviewed the susceptibility-weighted images. Glioblastomas have a clearly higher grade of susceptibility signals than lymphomas. By additionally using susceptibility-weighted images, the radiologists determined the correct diagnosis in 82.2 % of the cases. Without susceptibility-weighted images, the diagnosis was correct in 75.5 % of the cases. The subjective gain of certainty was 16.5 %. If there were no intratumoral susceptibility signals (ITSS) (grade 1), the sensitivity for diagnosing a lymphoma was 70 % and the specificity was 100 %. The sensitivity for diagnosing a glioblastoma was 90.5 % and the specificity was 100 % if there was a high rate of intratumoral susceptibility signals (grade 3). Susceptibility-weighted images are an additional tool in clinical practice for determining the correct diagnosis. The differentiation between glioblastomas and lymphomas and the certainty of the determined diagnosis are better. Therefore, we recommend adding susceptibility-weighted imaging to the clinical MR tumor protocol.

Precontrast and postcontrast susceptibility-weighted imaging in the assessment of intracranial brain neoplasms at 1.5 T

The goal of this study was to estimate pre- and post-gadolinium-enhanced high-spatial resolution susceptibility-weighted imaging (SWI) in patients with brain neoplasms. A total of 17 patients (8 women, 9 men) with brain neoplasms participated in this study. In addition to conventional magnetic resonance imaging, pre- and post-gadolinium-enhanced SWI was performed. The contrast-to-noise ratio (CNR) and major diameters of the brain tumor were measured for quantitative analyses, and intratumoral susceptibility signal intensity (ITSS) was graded for semiquantitative analysis. Both bright and dark enhancement were observed at the pathological lesion on postcontrast SWI. Some postcontrast SWI results suggested leakage of contrast material due to breakdown of the blood-brain barrier. There were no statistical differences (Student's t-test) between postcontrast SWI and three-dimensional (3D) T1-weighted images regarding the major diameters of the brain tumors. CNR of postcontrast 3D T1-weighted images was statistically superior to that of postcontrast SW images (P < 0.01, Wilcoxon signed-rank test). Malignant tumors tended to have a higher ITSS score. SWI clearly visualized the architecture of brain neoplasms. This imaging technique may be useful for evaluating tumor characterization in clinical use.