Can tumor contrast enhancement be used as a criterion for differentiating tumor grades of oligodendrogliomas?

BACKGROUND AND PURPOSE: The association of high-grade oligodendrogliomas with tumor contrast material enhancement on MR images has been reported. Some authors have even used contrast enhancement as a criterion for their oligodendroglioma grading system. The purpose of our study was to evaluate if tumor contrast enhancement is a specific finding for anaplastic oligodendroglioma. METHODS: Pretreatment MR images of 24 oligodendrogliomas were reviewed retrospectively, and findings were compared with the histologic grade. The presence or absence and the pattern of tumor contrast enhancement were evaluated qualitatively. A contrast enhancement ratio (CER), a quantitative criterion, was calculated to assess the difference in degree of enhancement between the low-grade and anaplastic tumors. Tumor grade was diagnosed at pathologic examination according to the World Health Organization classification system. RESULTS: Contrast enhancement was noted in nine (56%) of 16 low-grade tumors and in five (62%) of eight anaplastic tumors. A characteristic enhancement pattern, nodular-like enhancement, was found in eight tumors. The CERs were 2.12-40.88 (mean, 20.08) in low-grade tumors and were 3.20-62.52 (mean, 28.73) in anaplastic tumors (P > .05). CONCLUSION: Tumor contrast enhancement was not statistically significantly different between the tumor groups. We believe that the presence or absence of tumor contrast enhancement is not a specific finding for simply discriminating low-grade from anaplastic oligodendrogliomas. Histologic confirmation is necessary even in tumors without contrast enhancement.     

Can diffusion weighted image and apparent diffusion coefficient (ADC) differentiate benign from malignant cervical adenopathy?

Background

Cervical adenopathy is a common problem and the differentiation of benign and malignant node is of crucial importance for therapy management.

Objective

This prospective study aimed to know if Diffusion weighted images (DWI) and apparent diffusion coefficient (ADC) can differentiate benign from malignant cervical lymphadenopathy.

Patients and methods

Thirty patients with cervical adenopathy were included in this study. Doppler ultrasound, DWI and ADC maps were automatically reconstructed and used for the measurement of ADC values.

Results

The sensitivity and specificity of the RI cut-off value <0.69 in differentiation between benign and malignant cervical L.Ns was 88.8% and 71.4%, respectively. The optimal ADC cut off value for differentiation between benign and malignant lymph nodes was ?1.0 × 10⁻³ mm²/s with an accuracy 96.7%, a sensitivity 100%, a specificity 88.9%, PPV 95.4% and NPV 100% and statistically significant P-value = 0.000.

Conclusion

DWI and ADC were useful for differentiation between benign and malignant cervical lymphadenopathy and recommended to decrease the need of invasive biopsies. However, CDUS techniques can be used as preliminary technique but, they had potential pitfalls in diagnosis of malignant cervical lymphadenopathy cases.     

Assessment of tumor heterogeneity by CT texture analysis: Can the largest cross-sectional area be used as an alternative to whole tumor analysis?

Objective

To determine if there is a difference between contrast enhanced CT texture features from the largest cross-sectional area versus the whole tumor, and its effect on clinical outcome prediction.

Methods

Entropy (E) and uniformity (U) were derived for different filter values (1.0–2.5: fine to coarse textures) for the largest primary tumor cross-sectional area and the whole tumor of the staging contrast enhanced CT in 55 patients with primary colorectal cancer. Parameters were compared using non-parametric Wilcoxon test. Kaplan–Meier analysis was performed to determine the relationship between CT texture and 5-year overall survival.

Results

E was higher and U lower for the whole tumor indicating greater heterogeneity at all filter levels (1.0–2.5): median (range) for E and U for whole tumor versus largest cross-sectional area of 7.89 (7.43–8.31) versus 7.62 (6.94–8.08) and 0.005 (0.004–0.01) versus 0.006 (0.005–0.01) for filter 1.0; 7.88 (7.22–8.48) versus 7.54 (6.86–8.1) and 0.005 (0.003–0.01) versus 0.007 (0.004–0.01) for filter 1.5; 7.88 (7.17–8.54) versus 7.48 (5.84–8.25) and 0.005 (0.003–0.01) versus 0.007 (0.004–0.02) for filter 2.0; and 7.83 (7.03–8.57) versus 7.42 (5.19–8.26) and 0.005 (0.003–0.01) versus 0.006 (0.004–0.03) for filter 2.5 respectively (p ≤ 0.001). Kaplan–Meier analysis demonstrated better separation of E and U for whole tumor analysis for 5-year overall survival.

Conclusion

Whole tumor analysis appears more representative of tumor heterogeneity.     

Can preoperative lymphoscintigraphy be used as a guide in treatment planning of breast cancer?

PURPOSE: The purpose of this study was to map the lymphatic drainage patterns of breast cancer with lymphoscintigraphy to evaluate the variability of drainage and to determine whether lymphatic mapping can help to increase the certainty of breast cancer staging. MATERIALS AND METHODS: Fifty women with breast cancer (mean age, 49 years) were included in the study. Lymphoscintigraphy was performed with 1 mCi Tc-99m rhenium sulfide colloid in a 2-ml volume injected into the four quadrants of the peritumoral area using a 25-gauge needle. Ten-minute dynamic images and 2-hour delayed static images were obtained in the anterior and lateral positions using a gamma camera with a high-resolution collimator. All patients had a modified radical mastectomy and axillary dissection. The results were evaluated with histopathologic findings of the axilla. RESULTS: Six patients had excision biopsies before surgery. Of 13 patients with centrally located tumors, 84% had axillary lymphatic drainage, whereas 53% drained to internal mammary lymphatics. Of 23 patients with outer quadrant tumors, 4 showed no lymphatic drainage and all of them had metastatic tumor in the axillary lymph nodes. Axillary drainage was seen in 82% of patients and internal mammary lymphatic drainage in 23%. Of eight patients with inner quadrant tumors, one patient with no lymphatic drainage was found to have metastases in the axilla. In this group, 62% had axillary and 50% had internal mammary lymphatic drainage, and one patient had supraclavicular drainage. CONCLUSIONS: Lymphoscintigraphy indicates that drainage routes may vary, and thus it may play a guiding role in patients with breast cancer who need radiotherapy. In patients with internal mammary lymphatic drainage, the accuracy of radiotherapy planning may increase if internal mammary lymphoscintigraphy is added to the protocol. In patients with internal mammary drainage, obtaining an internal mammary lymphatic biopsy during surgery will also increase the accuracy of staging.     

Can the ZoMBieS method be used to characterise scintillator non-linearity?

Measurements of the detection efficiency as a function of deposited electron energy in a liquid scintillation cocktail between 4 keV and 49 keV are obtained using the ZoMBieS method. Comparison is made between the measured data and the Poisson–Birks detection efficiency model. Measurements of the Birks non-linearity parameter, kB, and the linearised scintillation response of each photomultiplier, ω_i, were made using these data. However, the value of kB that best linearises the scintillator response is found to vary depending upon which photomultiplier is used in its determination, and the measured kB and ω_i vary depending on the external source geometry. The cause of this behaviour is unknown. The triple-coincident detection efficiency appears to be unaffected by any systematic errors.     

Measurement of the apparent diffusion coefficient in the liver: is it a reliable index for hepatic disease diagnosis?

Purpose The aim of this study was to determine the validity of the hepatic apparent diffusion coefficient (ADC) measurement. The influence of differences in measured location and administration of Buscopan (hyoscine butylbromide) for ADC were assessed. Materials and methods SENSE-DWI (b = 0, 500) was obtained before and after Buscopan administration to 30 patients suspected of having a liver tumor. In this sequence, respiration gating was employed, but cardiac triggering was not. ADC measurement was performed in the hepatic parenchyma of both right and left lobes in selected slices. A statistical analysis was performed to estimate the correlation among ADC, measured location, Buscopan, and pulse rate. The images were visually evaluated to categorize the subcardiac signal loss in the left lobe. Results The ADC showed higher values in the left lobe than in the right lobe in both pre- and postloaded studies (P < 0.001). In a comparison between ADCs in the pre- and postloaded studies, the differences were not significant in the left lobe (P = 0.93) or the right lobe (P = 0.41). No correlation was noted between ADCs and the pulse rate. Visual evaluation revealed that the subcardiac signal loss was more prominent in the postloaded study. Conclusion ADC measurement of the left hepatic lobe was far more incorrect than that of the right lobe if cardiac gating was not employed. The administration of Buscopan worsened the image quality of the left lobe and made visual evaluation difficult. This article was presented at the Japan Radiological Society meeting in 2005.     

Can FDG PET be used to successfully direct preoperative biopsy of soft tissue tumours?

Magnetic resonance imaging (MRI) has been the most useful tool in the anatomical definition of soft tissue sarcoma, although there remains the problem of defining the lesions as benign or malignant. The management of such lesions requires biopsy prior to surgical resection. If the most malignant area could be defined more accurately, then this area could be targeted for biopsy. Fluorodeoxyglucose positron emission tomography (FDG PET) has been found to be useful in identifying malignancy and variations in grade in soft tissue masses. The aim of this study was to assess the use of FDG PET scanning with or without co-registered MRI to indicate the most appropriate biopsy site. Twenty consecutive patients presented with soft tissue masses with clinical signs of malignancy. All patients underwent MRI and FDG PET scanning and the two images were co-registered. A biopsy site that was the most likely to be malignant was defined on the PET scan. All patients underwent an initial biopsy and then complete surgical resection of the mass. The histological results from the mass were compared with those from the biopsy specimen obtained from the site suggested by the PET scan. In malignant masses the biopsy site suggested by the FDG PET scan was found to be representative of the most malignant site on the whole mass histology. Benign lesions had low or no FDG uptake. In no case did the co-registered image add significantly to the appropriate biopsy site. FDG PET can be used to appropriately direct biopsy in soft tissue sarcoma and potentially may lead to computed tomography/MRI directed outpatient biopsy prior to definitive treatment.     

Can diffusion-weighted imaging be used to differentiate benign from pathologic fractures? A meta-analysis

OBJECTIVE: Conventional MR sequences are sometimes nonspecific in differentiating benign from pathologic fractures. To address this difficulty, diffusion-weighted images were conjectured to aid in this discrimination with variable results. As each of these studies contained somewhat small numbers of patients, we performed a meta-analysis to determine if this sequence may be used for this important diagnostic problem. MATERIALS AND METHODS: We reviewed and statistically analyzed the results of eight studies, performed between 1998 and 2003, comparing diffusion-weighted magnetic resonance signal intensity characteristics of benign and pathologic vertebral body fractures. Diffusion-weighted imaging (DWI) signal characteristics and apparent diffusion coefficient (ADC) values of 104 benign fractures and 161 combined malignant vertebral body lesions and pathologic fractures were statistically evaluated in terms of mean ADC, as well as percentage classified as either hypointense or isointense. The meta-analysis to compare benign fractures with the combined pathologic fractures and metastatic lesions in terms of mean ADC used Hedge's g statistic with a small sample bias adjustment; the comparison of the percentage hypo- or isointense used the Mantel-Haenszel method to calculate a weighted summary odds ratio. All summary effect sizes were computed under a random effects model to account for study heterogeneity. RESULTS: The mean ADC was significantly higher (p < 0.01) among benign fractures, with a standardized mean difference (SMD) of 2.8 and a 95% confidence interval (CI) for the SMD of 2.1 to 3.5. Lesions classified as hypointense were significantly more likely to be benign (p < 0.01), based on a summary odds ratio (OR) of 24.5 and 95% confidence that the OR exceeds 1.7. Lesions classified as isointense were not significantly more likely to be benign or malignant (p > 0.1), based on a summary OR of 3.6 and a 95% CI for the OR of 0.35 to 36.6. CONCLUSION: Even though the literature has been inconsistent, ADC maps appear to be a reliable method to differentiate benign from malignant fractures.     

Is apparent diffusion coefficient reliable and accurate for monitoring effects of antiangiogenic treatment in a longitudinal study?

Purpose:

To evaluate the reliability and accuracy of the apparent diffusion coefficient (ADC) for monitoring antiangiogenic treatment in a longitudinal study.

Materials and Methods:

Tumor volume and ADC were monitored by T2‐weighted magnetic resonance imaging (MRI) and diffusion‐weighted MRI, respectively, in 18 mice with angiogenesis‐dependent tumors (U118MG) before (day 0) and after 2, 7, 14, and 21 days of administration of the antiangiogenic agent sunitinib maleate (n = 12) or vehicle (n = 6). Percent changes in tumor volume and ADC were calculated and correlations between tumor volume and ADC were evaluated.

Results:

Tumor volume and ADC showed a negative correlation at 69 of the 72 (96%) follow‐up measurements. In the 13 mice with tumor regrowth, ADC started to decrease before (27%) or at the same time (73%) as tumor regrowth. Pretreatment ADC and percent change in ADC change on days 0–2 were similar in mice with positive and negative responses to treatment (0.851 vs. 0.999, 24% vs. 16%). Percent change of ADC showed significant negative correlation with percent change in tumor volume in both the control (r = ?0.69) and treated (r = ?0.65) groups.

Conclusion:

Percent change in ADC is a reliable and accurate marker for monitoring the effects of antiangiogenic treatment, whereas pretreatment ADC and early changes in ADC (ie, days 0–2) are limited in predicting treatment outcome. J. Magn. Reson. Imaging 2012;35:1430–1436. © 2012 Wiley Periodicals, Inc.

     

Can the MRI signal of aggressive fibromatosis be used to predict its behavior?

Purpose

Aggressive fibromatosis is an invasive non-metastasizing soft-tissue tumor. Until recently, the standard treatment combined surgery and radiation therapy, but new studies reported that conservative strategies with or without medical treatment could be the best management. The aim of this study was to analyze and correlate the size and MR imaging signal features of aggressive fibromatosis with its behavior in order to choose the best treatment.

Materials and methods

Between March 1985 and December 2005, 27 patients with at least 2 consecutive MRI examinations and no surgery or radiation therapy in between were recorded. There were 9 men and 18 women, and median age was 31 years. They underwent 107 MRI examinations of 47 lesions, 29 of which were medically treated, while the remaining 18 did not receive any drug administration. The size and signal changes of each lesion were studied over time on T2- and/or T1-weighted sequences after injection of contrast medium. RECIST criteria were used for size: only a 30% decrease or a 20% increase in the size of the main dimension was considered significant. We classified the appearance of the signal into six categories in order of increasing intensity and then we established the related variations over time.

Results

The size of 79% of the lesions in the treated group and 82% in the untreated group remained stable. The initial signal of stable lesions or those exhibiting an increase in size was most frequently high. There was a high rate of signal stability over time, whatever the initial signal and size changes. Changes in size were not correlated with the initial MR signal. A decrease in size associated with a decreased signal was observed in three cases exclusively in the treated group.

Conclusion

Fibromatoses are a group of soft-tissue tumors with variable characteristics on MRI, but it is not possible to predict their behavior based on the MRI signal.     

Can evoked phonomyography be used to recognize fast and slow muscle in man?

The present study is aimed at ascertaining if muscle sound might be used as a detector of the contractile properties of individual human muscles "in vivo". In order to test this hypothesis, Soleus muscle (slow) and Vastus Lateralis Femoris muscle (fast) were investigated in three healthy subjects during electrically elicited contractions. Evoked phonomyograms were obtained from isometric single twitch contractions using a microphonic apparatus. Time and frequency domain analysis were performed. Evoked phonomyogram rising time values obtained from the two muscles are significantly different (p less than .01) and this difference is clearly due to their different mechanical properties. The power spectrum of all signals was obtained by means of harmonic analysis routine and mean frequency thus obtained was taken into account. Power spectrum values are approximately 1.5 times greater in fast muscle than in slow muscle (p less than .01). These findings lead us to the conclusion that evoked phonomyography can be considered a useful technique for the assessment of mechanical properties of individual human muscles.     

Clinical utility of apparent diffusion coefficient (ADC) values in patients with prostate cancer: Can ADC values contribute to assess the aggressiveness of prostate cancer?

Purpose

To retrospectively evaluate the relationship between apparent diffusion coefficient (ADC) values and Gleason score (GS) in prostate cancer.

Methods

A total of 60 patients who underwent radical prostatectomy for clinically localized prostate cancer were selected for this study. Diffusion‐weighted magnetic resonance (MR) images were obtained using a 1.5 T system. ADC values were analyzed between three groups: GS of 6 or less (n = 7); GS of 7 (n = 37); and GS of 8 or higher (n = 16). ADC values of the three GS groups were statistically analyzed in order to determine the relationship with GS. In the 37 patients with GS = 7 the difference in ADC values between GS 3+4 and GS 4+3 was analyzed.

Results

Median ADC values (10^?3 mm²/s) of the three GS groups were 1.04 (GS = 6 or less), 0.867 (GS = 7), and 0.729 (GS = 8 or higher). Although there was considerable overlap among the groups, the differences in ADC were statistically significant (P < 0.0001). There was a significant inverse correlation between GS and ADC values (z = ?0.437, P < 0.0005). Median ADC values (10^?3 mm²/s) of GS 3+4 and GS 4+3 patients were 0.88 and 0.814, respectively (P < 0.05).

Conclusion

ADC values showed a negative correlation with GS. Pathologically, however, there was considerable intrasubject heterogeneity. J. Magn. Reson. Imaging 2011;33:167–172. © 2010 Wiley‐Liss, Inc.