Diffusion-weighted Imaging of Breast Cancer with the Sensitivity Encoding Technique: Analysis of the Apparent Diffusion Coefficient Value

[Investigation of a phantom for diffusion weighted imaging that controlled the apparent diffusion coefficient using gelatin and sucrose]

When studying diffusion weighted imaging(DWI), it is important to create a phantom that has a reliably controlled diffusion coefficient. In this study, we investigated phantoms to control both the diffusion coefficient and the T2-value by changing the concentration of gelatin or sucrose and MnCl(2), respectively. The results showed that the diffusion coefficient decreased linearly with increases in the gelatin or sucrose concentration, and decreasing of their relaxation times was observed. By properly adjusting the MnCl(2) concentrations, we were able to equalize the T2-values between phantoms having different gelatin or sucrose concentrations. Temperature dependence of the diffusion coefficient was also revealed. This phantom can be made stable for a few months by adding a small amount of NaN(3) as an antiseptic agent, has a diffusion coefficient similar to that of neural tissue or clinical tumor, and is able to control the T2-value properly. We consider this phantom suitable for studying SE-type DWI and contributes to elucidation of this technique.

Usefulness of diffusion-weighted imaging in the evaluation of renal masses

OBJECTIVE

The objective of our study was to assess the value of diffusion-weighted imaging in differentiating among the various subgroups of renal masses.

MATERIALS AND METHODS

This retrospective study measured the apparent diffusion coefficients (ADCs) of renal masses. Malignant lesions were confirmed with surgical pathology results. Benign cystic lesions were stable without treatment for a minimum follow-up of 24 months.

RESULTS

There were 20 and 22 patients, respectively, with benign lesions (three abscess, 31 cysts) and malignant lesions (17 clear cell, five papillary, one chromophobe, and two transitional cell cancers). The malignant lesions were larger than the benign lesions (mean diameter, 4.2 vs 2.6 cm, respectively; p = 0.01, Student's t test). The ADC values of the benign lesions were significantly higher than those of the malignant lesions (mean, 2.72 vs 1.88 x 10(-3) mm(2)/s; p < 0.0001). The ADCs of the 31 benign cysts were significantly higher than those of the seven cystic renal cancers (2.77 vs 2.02 x 10(-3) mm(2)/s; p < 0.001). There was no significant difference between the ADCs of clear cell cancers and non-clear cell cancers (1.85 vs 1.97 x 10(-3) mm(2)/s; p = 0.18), but an ADC of less than 1.79 x 10(-3) mm(2)/s was seen only with clear cell cancer. The ADCs of high-grade clear cell cancers (Fuhrman grades III and IV) tended to be lower than those of low-grade clear cell cancers (1.77 vs 1.95 x 10(-3) mm(2)/s; p = 0.12). Among the clear cell cancers, an ADC value of greater than 2.12 x 10(-3) mm(2)/s was seen only with low-grade histology. For differentiating benign from malignant lesions, receiver operating characteristic (ROC) analysis showed an area under the ROC curve of 0.989 (95% CI, 0.919-0.996; p < 0.0001).

CONCLUSION

ADC measurements may aid in differentiating among the various subgroups of renal masses, particularly benign cystic lesions from cystic renal cell cancers.

DWI in breast MRI: role of ADC value to determine diagnosis between recurrent tumor and surgical scar in operated patients

INTRODUCTION

Purpose of our study is to evaluate the role of the apparent diffusion coefficient (ADC) in the diagnosis of recurrent tumor on the scar in patients operated for breast cancer. Assess, therefore, the weight of diagnostic diffusion echo-planar sequence, in association with the morphological and dynamic sequences in the diagnosis of tumor recurrence versus surgical scar.

MATERIALS AND METHODS

From September 2007 to March 2009, 72 patients operated for breast cancer with suspected recurrence on the scar were consecutively subjected to magnetic resonance imaging (MRI), including use of a diffusion sequence. All patients with pathological enhancement in the scar were then subjected to histological typing. MRI was considered negative in the absence of areas of suspicious enhancement. In all cases it was measured the ADC value in the scar area or in the area with pathological enhancement. The ADC values were compared with MRI findings and histological results obtained.

RESULTS

26 cases were positive/doubtful at MRI and then subjected to histological typing: of these recurrences were 20 and benign were 6. 46 cases were judged negative at MRI and therefore not sent to cyto-histology. The average ADC value of recurrences was statistically lower of scarring (p<0.001).

CONCLUSIONS

ADC value can be a specific parameter in differential diagnosis between recurrence and scar. The diffusion sequence, in association with the morphological and dynamic sequences, can be considered a promising tool for the surgical indication in suspected recurrence of breast cancer.

Detection of bone metastases using diffusion weighted magnetic resonance imaging: comparison with (11)C-methionine PET and bone scintigraphy

PURPOSE

We evaluated the ability of diffusion-weighted imaging (DWI) to detect bone metastasis by comparing the results obtained using this modality with those obtained using (11)C-methionine (MET) positron emission tomography (PET) and bone scintigraphy.

MATERIALS AND METHODS

This retrospective study involved 29 patients with bone metastasis. DWI was obtained using a single-shot echo planar imaging (EPI) sequence with fat suppression using a short inversion time inversion recovery sequence. The detection capabilities of DWI for bone metastases were compared with those of whole body MET PET (in 19 patients) and 99mTc-methylene diphosphonate bone scintigraphy (in 15 patients).

RESULTS

Among the 19 patients who were diagnosed using DWI and PET, the PET identified 39 bone metastases, while the DWI identified 60 metastases out of 69 metastases revealed with conventional magnetic resonance imaging (MRI). Among the 15 patients who were diagnosed using DWI and bone scintigraphy, the bone scintigraphy identified 18 bone metastases, while the DWI identified 72 metastases out of 78 metastases revealed with conventional MRI. The overall bone metastasis detection rates were 56.5% for PET, 23.1% for bone scintigraphy and 92.3% for DWI.

CONCLUSION

DWI is a very sensitive method for detecting bone metastasis and is superior to MET PET and bone scintigraphy in terms of its detection capabilities.

Sensitivity and specificity of unenhanced MR mammography (DWI combined with T2-weighted TSE imaging, ueMRM) for the differentiation of mass lesions

OBJECTIVE

This study was performed to assess the sensitivity and specificity for malignant and benign mass lesions of a diagnostic approach combining DWI with T2-weighted images (unenhanced MR mammography, ueMRM) and compare the results with contrast-enhanced MR mammography (ceMRM).

MATERIALS AND METHODS

Consecutive patients undergoing histopathological verification of mass lesions after MR mammography without prior breast interventions (contrast-enhanced T1-weighted, T2-weighted and DWI sequences) were eligible for this retrospective investigation. Two blinded observers first rated ueMRM and then ceMRM according to the BIRADS scale. Lesion size, ADC values and T2-weighted TSE descriptors were assessed.

RESULTS

This study examined 81 lesions (27 benign, 54 malignant). Sensitivity of ueMRM was 93% (observer 1) and 86% (observer 2), respectively. Sensitivity of ceMRM was 96.5% (observer 1) and 98.3% (observer 2). Specificity was 85.2% (ueMRM) and 92.6% (ceMRM) for both observers. The differences between both methods and observers were not significant (P > or = 0.09). Lesion size measurements did not differ significantly among all sequences analyzed. Tumor visibility was worse using ueMRM for both benign (P < 0.001) and malignant lesions (P = 0.004).

CONCLUSION

Sensitivity and specificity of ueMRM in mass lesions equal that of ceMRM. However, a reduced lesion visibility in ueMRM may lead to more false-negative findings.

[A study of ADC value in PROPELLER DWI]

Diffusion weighted imaging(DWI)is rapidly becoming widespread in MRI, with many reports of the differential diagnosis using the Apparent Diffusion Coefficient(ADC)being seen. We examined the influence of scan parameter on ADC in PROPELLER-DWI. Neither the TR nor T1 value had a major influence on the ADC value. Number of MPG pulse, effective TE, and T2 value were the factors in which the ADC value was changed. In addition, the ADC value has been changed by the scan sequence. The factor that influenced the ADC value was able to be confirmed by this experiment. It is necessary to understand the influence that an individual factor has on ADC.

Diffusion-weighted imaging in breast lesion evaluation

PURPOSE

The purpose of this study was to investigate the ability of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in the detection and characterisation of breast lesions.

MATERIALS AND METHODS

From September 2005 to September 2007, 86 patients with breast lesions who underwent magnetic resonance imaging (MRI) in our department were included in our study. MRI was performed with a 1.5-T unit using a standard protocol including DWI sequence. For each breast lesion, the ADC value was calculated and compared with that of normal breast tissue and to the definitive pathological diagnosis. Mann-Whitney U and Kruskal-Wallis tests were used for statistical analysis.

RESULTS

A total of 126 breast lesions were detected. Pathology results revealed 100 malignant and 26 benign lesions. Mean diameter of lesions was 26.02 mm (range 4-90 mm), including 52 lesions <or=15 mm in size. Mean ADC value of normal glandular tissue was 1.55x10(-3) mm(2)/s. Mean ADC value of malignant lesions was 0.97x10(-3) mm(2)/s. Mean ADC value for benign lesions was 1.66x10(-3) mm(2)/s. Benign lesions showed ADC values significantly higher than malignant lesions (p<0.0001).

CONCLUSIONS

DWI provides reliable information to support MRI diagnosis of breast masses. ADC value appears a promising adjunctive parameter in distinguishing malignant from benign breast lesions.

Candidate biomarkers of extravascular extracellular space: a direct comparison of apparent diffusion coefficient and dynamic contrast-enhanced MR imaging--derived measurement of the volume of the extravascular extracellular space in glioblastoma multiforme

BACKGROUND AND PURPOSE

ADC measurements have been shown to have an inverse relationship with tumor cell density. DCE-MR imaging modeling techniques can produce a measurement of the v(e), which would also be expected to have an inverse relationship with cell density. The objective of this study was to test the hypothesis that areas of increased cellularity, and therefore low ADC, would be expected to have a small EES (low v(e)).

MATERIALS AND METHODS

Nineteen patients with GBM were recruited. All imaging was performed before surgery on a 3T MR imaging scanner. Imaging included diffusion tensor imaging, T1-weighted DCE-MR imaging, and anatomic sequences. Tumor VOIs were defined on the anatomic images and modified to contain only enhancing voxels. Parametric maps of ADC and v(e) were generated. Statistical analysis of ADC and v(e) was performed on both a voxel-by-voxel basis and comparison of median values.

RESULTS

No correlation was demonstrated between ADC and v(e) in either a voxel-by-voxel analysis or comparison of median values (P = .124).

CONCLUSIONS

This study failed to demonstrate a correlation between ADC and v(e). This is important because it suggests that though the mechanisms underlying these parameters are theoretically similar, they actually reflect different aspects of tumor microenvironment. Consequently ADC and v(e) should be considered to provide independent information about the properties of the EES.

Assessment of breast lesions with diffusion-weighted MRI: comparing the use of different b values

OBJECTIVE

Our purpose was to study the utility of diffusion-weighted MRI in differentiating benign from malignant breast lesions by assessing the best b values.

SUBJECTS AND METHODS

Forty-five women (mean age, 46.1 years) with 52 focal mass breast lesions underwent diffusion-weighted imaging with different b values. The apparent diffusion coefficient (ADC) value of each lesion was calculated from the ADC maps done using five b values (0, 250, 500, 750, and 1,000 s/mm(2)) and using b values of 0 s/mm(2) with each other b value separately (0 and 250 s/mm(2), 0 and 500 s/mm(2), 0 and 750 s/mm(2), 0 and 1,000 s/mm(2)). The mean ADC values were correlated with imaging findings and histopathologic diagnoses. The cutoff ADC value, sensitivity, and specificity of diffusion-weighted imaging to differentiate benign and malignant lesions were calculated in all b value combinations. A p value of < 0.05 was considered statistically significant.

RESULTS

The mean ADC value was significantly lower for malignant lesions compared to benign lesions (p < 0.0001) in all b value combinations. No statistical difference was seen between the ADC obtained from different b value combinations (p = 0.2581) in the differentiation between benign and malignant lesions. The ADC calculated from b 0 and 750 s/mm(2) was slightly better than the other b value combinations, showing a sensitivity of 92.3% and a specificity of 96.2%.

CONCLUSION

Diffusion-weighted imaging is a potential resource as a coadjutant of MRI in the differentiation between benign and malignant lesions. Such imaging can be performed without a significant increase in examination time, especially because it can be done with lower b values.

O uso da difusão por ressonância magnética na diferenciação das lesões mamárias benignas e malignas

OBJETIVO: Estudar a utilidade da sequência pesada em difusão na diferenciação das lesões mamárias benignas e malignas. MATERIAIS E MÉTODOS: Quarenta e cinco mulheres (idade média de 46,1 anos) com 52 nódulos de mama foram submetidas a ressonância magnética acrescida da sequência difusão. O coeficiente de difusão aparente (ADC) foi calculado através do mapa de ADC obtido pelo uso de cinco valores de b (0, 250, 500, 750 e 1.000 s/mm²). O valor de ADC médio de cada lesão foi correlacionado com achados de imagem e resultados histopatológicos. Valores de ADC de corte, sensibilidade e especificidade da sequência difusão na diferenciação das lesões benignas e malignas foram calculados. P < 0,05 foi considerado estatisticamente significativo. RESULTADOS: O valor de ADC médio foi significativamente menor para as lesões malignas (0,92 ± 0,26 × 10-3 mm²/s) comparado com as lesões benignas (1,50 ± 0,34 × 10-3 mm²/s) (p < 0,0001). A sequência difusão mostrou altas sensibilidade e especificidade (ambas 92,3%) na diferenciação entre lesões benignas e malignas. CONCLUSÃO: A sequência pesada em difusão representa um recurso potencial como coadjuvante da ressonância magnética das mamas na diferenciação das lesões benignas e malignas. Tal sequência pode ser facilmente inserida no protocolo padrão da ressonância magnética das mamas, sem aumento significativo no tempo de exame.

Non-mass-like enhancement on contrast-enhanced breast MR imaging: lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

PURPOSE

To evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted MR imaging (DWI) in characterization of lesions showing non-mass-like enhancement on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

MATERIALS AND METHODS

We analyzed consecutive MR images in 45 lesions showing non-mass like enhancement in 41 patients. We analyzed lesion size, distribution, internal enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators for malignancy. In a validation study, 22 non-mass-like enhancement lesions in 21 patients were examined. We calculated diagnostic accuracy when we presume category 4b, 4c, and 5 lesions as malignant or high to moderate suspicion for malignancy, and category 4a and 3 as low suspicion for malignancy or benign.

RESULTS

Segmental distribution (P=0.018), clumped internal enhancement (P=0.005), and ADC less than 1.3 x 10(-3) mm(2)/s (P=0.047) were the strongest MR indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 87% (13/15), 86% (6/7), 93% (13/14), 75% (6/8) and 86% (19/22), respectively.

CONCLUSION

The combination of DCE-MRI and DWI showed high diagnostic accuracy in characterization of non-mass-like enhancement lesions on breast MR images.

1H MR spectroscopy and diffusion-weighted imaging of the breast: are they useful tools for characterizing breast lesions before biopsy?

OBJECTIVE

The objective of our study was to determine whether proton ((1)H) MR spectroscopy (MRS) and diffusion-weighted imaging might be useful tools for characterizing breast lesions before biopsy.

MATERIALS AND METHODS

Single-voxel (1)H MRS and diffusion-weighted imaging were performed in 171 suspicious or highly suspicious lesions. Using the residual water signal as a reference (4.7 ppm), a choline peak at 3.22-3.23 ppm was defined as malignant. If a high-signal-intensity lesion was detected in high-b-value (b = 1,500 s/mm(2)) images, that lesion was defined as positive for malignancy. Among the patients with positive results on diffusion-weighted imaging, the apparent diffusion coefficient (ADC) values of the mass or focus were calculated from two different gradient factors (b(1) = 500 s/mm(2) and b(2) = 1,500 s/mm(2)).

RESULTS

The diagnostic sensitivity and specificity of (1)H MRS were 44% (40/91) and 85% (68/80), respectively (p < 0.001). If (1)H MRS was applied for mass lesions larger than 15 mm, the diagnostic sensitivity and specificity were 82% (28/34) and 69% (11/16), respectively. Of the high-b-value images, 24 benign lesions and eight nonmass ductal carcinoma in situ were visually negative. With the use of a cutoff ADC value of 1.13 x 10(-3) mm(2)/s, a specificity of 67% (43/64) and sensitivity of 97% (61/63) was obtained on diffusion-weighted imaging.

CONCLUSION

(1)H MRS was useful for characterizing breast lesions measuring 15 mm or larger, and diffusion-weighted imaging was useful for characterizing lesions of any size. However, these two techniques still have potential pitfalls in relation to the diagnosis of nonmass breast lesions.

Diffusion-weighted imaging of surgically resected hepatocellular carcinoma: imaging characteristics and relationship among signal intensity, apparent diffusion coefficient, and histopathologic grade

OBJECTIVE

The objective of our study was to determine the relationship between the signal intensity of hepatocellular carcinoma (HCC) assessed with diffusion-weighted imaging (DWI) and T2-weighted imaging and the apparent diffusion coefficient (ADC) with the histopathologic grade of each nodule.

MATERIALS AND METHODS

MR examinations including DWI and T2-weighted imaging of 125 surgically resected hypervascular HCCs in 99 patients were retrospectively reviewed. Pathologic examinations revealed 25 well-, 61 moderately, and 39 poorly differentiated HCCs. Two radiologists reviewed the images and classified the signal intensity of each tumor on DWI and T2-weighted imaging by mutual agreement. The incidence of each signal intensity and the relationship between signal intensity and histopathologic grade were assessed for each sequence. The relationship between the ADC and histopathologic grade was also evaluated.

RESULTS

On DWI, 11 of 125 HCCs appeared hypo- to isointense, 27 tumors appeared slightly hyperintense, and the remaining 87 tumors appeared obviously hyperintense to the surrounding liver. Overall, 91.2% (114/125) of HCCs showed hyperintensity to the surrounding hepatic parenchyma. Statistical analysis showed that this rate on DWI was significantly higher than that on T2 turbo spin-echo (TSE) imaging (p < 0.001). On DWI, the tumors tended to show a brighter signal with rising histopathologic grade (p = 0.031), but this trend was not observed on T2-weighted imaging. ADC measurements revealed that the mean ADCs of well-, moderately, and poorly differentiated HCCs were approximately 1.45, 1.46, and 1.36 x 10(-3) mm(2)/s, respectively. There was no significant correlation between ADC and histopathologic grade.

CONCLUSION

The histopathologic grade of HCC had no correlation with the ADC, but HCC tumors tended to show a higher signal on DWI as the histopathologic grade rose. However, predicting the correct histopathologic grade of each HCC before surgery on the basis of DWI findings was difficult because of the large overlap among histopathologic grades.

[Breast MRI: the usefulness of diffusion-weighted sequences for differentiating between benign and malignant lesions]

OBJECTIVE

To evaluate the usefulness of diffusion-weighted MRI sequences and of the apparent diffusion coefficient (ADC) to differentiate between benign and malignant breast lesions.

MATERIAL AND METHODS

We prospectively studied 88 patients (aged 31 to 79 years) with 94 lesions (80 malignant and 14 benign) who were referred for preoperative local staging. All patients underwent dynamic MRI examination after intravenous contrast administration and a diffusion-weighted sequence with ADC calculation. The results obtained at diffusion-weighted imaging were correlated with those obtained at histological examination.

RESULTS

The mean value of the ADC for malignant lesions (1.12+/-0.25x10(-3)mm(2)/s) was significantly lower (p<0.001) than for benign lesions (1.61+/-0.52x10(-3)mm(2)/s). No significant differences in ADC values were found between the different subtypes of invasive carcinomas or between intraductal carcinoma and invasive carcinoma (p>0.05). Using an ADC lower than 0.95x10(-3)mm(2)/s as a threshold for malignancy, the sensitivity is 52% and the specificity is 100%.

CONCLUSION

Diffusion-weighted sequences provide additional information in breast MRI that is useful for differentiating between benign and malignant lesions, thus improving the specificity of the technique.

FDG-PET Dynamic Contrast-Enhanced CT in the Management of Breast Cancer

Breast cancer is a complex disease and molecular imaging may contribute to better management through providing new insight for early detection. Fluorodeoxyglucose (FDG)-PET/CT has made great strides as a functional anatomic technique and recently gained attention in the diagnosis, staging, and follow-up of breast cancer. FDG-PET and CT complement each other's strengths in integrated FDGPET/CT. One-stop-shop whole-body FDG-PET/CT coupled with integrated FDG-PET/CT mammography has also been advocated.

SSH-EPI diffusion-weighted MR imaging of the spine with low b values: is it useful in differentiating malignant metastatic tumor infiltration from benign fracture edema?

OBJECTIVE

Conventional MR sequences are sometimes not helpful in differentiating benign from pathologic fractures. Our aim was to evaluate the usefulness of single-shot echo-planar imaging sequences (diffusion-weighted imaging (DWI)/SSH-EPI) with low b value in differentiating malignant metastatic tumor infiltration of vertebral bone marrow from benign vertebral fracture edema.

MATERIALS AND METHODS

A total of 47 patients, 20 with benign fractures and 27 with tumor infiltration, were included in this prospective study. Diffusion-weighted MR images were obtained by single-shot echo-planar imaging technique with diffusion gradient (b = 300 s/mm2; TR/TE, 1,400/100), using a 1.5 T MR scanner. T1- and T2-weighted images and short inversion time inversion-recovery images were available for all 64 lesions. The lesions on DWI/SSH-EPI were categorized as having hypo-, iso-, or hyperintense signal intensity relative to normal vertebrae by two experienced radiologists.

RESULTS

We evaluated signal intensity patterns on DWI/SSH-EPI in 64 lesions, which showed low signal intensity on T1-weighted images in both benign fractures and metastasis. With the exception of sclerotic metastases in two patients, malignant metastatic tumor infiltration was hyperintense with respect to normal bone marrow on diffusion-weighted images; all but four benign vertebral fractures were isointense with respect to normal bone marrow.

CONCLUSION

Single-shot echo-planar imaging sequences (DWI/SSH-EPI) with low b value provided excellent distinction between metastatic tumor infiltration and benign vertebral fracture edema. Hyperintense signal intensity on DWI/SSH-EPI was highly specific for the diagnosis of metastatic tumor infiltration of the spine.

Comparison of diffusion-weighted images using short inversion time inversion recovery or chemical shift selective pulse as fat suppression in patients with breast cancer

PURPOSE

Fat suppression is essential for diffusion-weighted imaging (DWI) in the body. However, the chemical shift selective (CHESS) pulse often fails to suppress fat signals in the breast. The purpose of this study was to compare DWI using CHESS and DWI using short inversion time inversion recovery (STIR) in terms of fat suppression and the apparent diffusion coefficient (ADC) value.

MATERIALS AND METHODS

DWI using STIR, DWI using CHESS, and contrast-enhanced T1-weighted images were obtained in 32 patients with breast carcinoma. Uniformity of fat suppression, ADC, signal intensity, and visualization of the breast tumors were evaluated.

RESULTS

In 44% (14/32) of patients there was insufficient fat suppression in the breasts on DWI using CHESS, whereas 0% was observed on DWI using STIR (P < 0.0001). The ADCs obtained for DWI using STIR were 4.3% lower than those obtained for DWI using CHESS (P < 0.02); there was a strong correlation of the ADC measurement (r = 0.93, P < 0.001).

CONCLUSION

DWI using STIR may be excellent for fat suppression; and the ADC obtained in this sequence was well correlated with that obtained with DWI using CHESS. DWI using STIR may be useful when the fat suppression technique in DWI using CHESS does not work well.

Comparison of diffusion-weighted images using short inversion time inversion recovery or chemical shift selective pulse as fat suppression in patients with breast cancer

PURPOSE

Fat suppression is essential for diffusion-weighted imaging (DWI) in the body. However, the chemical shift selective (CHESS) pulse often fails to suppress fat signals in the breast. The purpose of this study was to compare DWI using CHESS and DWI using short inversion time inversion recovery (STIR) in terms of fat suppression and the apparent diffusion coefficient (ADC) value.

MATERIALS AND METHODS

DWI using STIR, DWI using CHESS, and contrast-enhanced T1-weighted images were obtained in 32 patients with breast carcinoma. Uniformity of fat suppression, ADC, signal intensity, and visualization of the breast tumors were evaluated.

RESULTS

In 44% (14/32) of patients there was insufficient fat suppression in the breasts on DWI using CHESS, whereas 0% was observed on DWI using STIR (P < 0.0001). The ADCs obtained for DWI using STIR were 4.3% lower than those obtained for DWI using CHESS (P < 0.02); there was a strong correlation of the ADC measurement (r = 0.93, P < 0.001).

CONCLUSION

DWI using STIR may be excellent for fat suppression; and the ADC obtained in this sequence was well correlated with that obtained with DWI using CHESS. DWI using STIR may be useful when the fat suppression technique in DWI using CHESS does not work well.

MRI methods for evaluating the effects of tyrosine kinase inhibitor administration used to enhance chemotherapy efficiency in a breast tumor xenograft model

PURPOSE

To evaluate whether quantitative MRI parameters are sensitive to the effects of the tyrosine kinase inhibitor gefitinib and can discriminate between two different treatment protocols.

MATERIALS AND METHODS

Untreated mice with BT474 breast tumor xenografts were characterized in a preliminary study. Subsequently, tumor volume, apparent diffusion coefficient (ADC), transendothelial permeability (K(ps)), and fractional plasma volume (fPV) were measured in three groups of mice receiving: 1) control vehicle for 10 days, or gefitinib as 2) a single daily dose for 10 days or 3) a 2-day pulsed dose.

RESULTS

Gefitinib treatment resulted in significant tumor growth inhibition (pulsed: 439 +/- 93; daily: 404 +/- 53; control: 891 +/- 174 mm(3), P < 0.050) and lower cell density (pulsed: 0.15 +/- 0.01, daily: 0.17 +/- 0.01, control: 0.24 +/- 0.01, P < 0.050) after 9 days. Tumor ADC increased in treated groups but decreased in controls (P > 0.050). Tumor K(ps) decreased with pulsed treatment but rebounded afterwards and increased with daily treatment (P > 0.050). Tumor fPV increased in both treated groups, decreasing afterwards with pulsed treatment (P > 0.050).

CONCLUSION

Quantitative MRI can provide a sensitive measure of gefitinib-induced tumor changes, potentially distinguish between treatment regimens, and may be useful for determining optimal treatment scheduling for enhancing chemotherapy delivery.

Diagnostic utility of diffusion-weighted magnetic resonance imaging in diabetic mastopathy

We report the clinical findings in a 36-year-old woman with diabetic mastopathy. The lesion showed heterogeneous segmental enhancement on magnetic resonance imaging (MRI), resembling a malignant lesion, but diffusion-weighted imaging (DWI) showed no abnormalities and the apparent diffusion coefficient value did not decrease. This case emphasizes the utility of DWI for differentiating diabetic mastopathy from malignant breast lesions. The value of DWI lies in its ability to exclude the possibility of malignant breast lesions and thus to avoid unnecessary biopsy.

Diffusion-weighted MR imaging with background body signal suppression (DWIBS) for the diagnosis of malignant and benign breast lesions

The purpose of this study was to evaluate the efficacy of diffusion-weighted MR imaging with background body signal suppression (DWIBS) and a conventional DWI (cDWI) sequence for the detection of breast lesions. Fifty consecutive patients with suspected breast lesions underwent DWIBS and cDWI at 1.5 T. The routine protocol consisted of a short TI inversion recovery (STIR) sequence and a dynamic contrast-enhanced T1-weighted sequence. Apparent diffusion coefficient (ADC) and exponential ADC (eADC) values of the lesions were calculated. Receiver operating characteristic (ROC) analyses and qualitative evaluation of lesion detectability and conspicuity were performed. Thirty-six lesions were detected in 30 patients by using the routine protocol. DWIBS detected 34 lesions (94%) and cDWI detected 26 lesions (72%). The conspicuity of fibroadenomas was significantly (P = 0.007) better for DWIBS. ADC and eADC values of tumour were significantly different between DWIBS and cDWI. DWIBS is superior to cDWI in the visualization of malignant and benign lesions in the breast.

Diffusion-weighted magnetic resonance imaging for characterization of focal liver masses: impact of parallel imaging (SENSE) and b value

PURPOSE

To evaluate the impact of parallel imaging (sensitivity encoding [SENSE] technique) on diffusion-weighted (DW) magnetic resonance imaging, compare DW imaging techniques with 2 different b values for characterization of focal hepatic lesions, and determine apparent diffusion coefficient cutoff values.

MATERIALS AND METHODS

Seventy-eight patients with 86 lesions were examined with 4 different DW techniques with 2 different b values (400 and 1000 s/mm2) and with/without the use of SENSE. The differences in signal-noise ratio values and image quality between DW images obtained with different techniques were compared using repeated-measures analysis of variance and Friedman test, respectively. A receiver operating characteristic analysis was applied to evaluate the apparent diffusion coefficient values as a discriminating variable to differentiate malignant lesions from benign ones; sensitivity and specificity were calculated.

RESULTS

There was no significant difference in the signal-noise ratio value and image quality between DW images obtained with b = 400 s/mm2 without SENSE (DW400) and b = 1000 s/mm2 with SENSE (DW1000SENSE). DW1000SENSE had the highest Az values for discriminating malignant from benign hepatic lesions (0.97) and hemangioma from metastasis (0.89). Using 1.63 x 10(-3) mm2/s as the cutoff value, DW1000SENSE had a sensitivity of 95.2% (40/42) and a specificity of 91.0% (40/44) for differentiating benign from malignant hepatic lesions. Using a cutoff value of 1.45 x 10(-3) mm2/s, DW1000SENSE had a sensitivity of 90.5% (19/21) and a specificity of 93.7% (15/16) for differentiating metastases from hemangiomas.

CONCLUSIONS

Diffusion-weighted imaging with a b value of 1000 s/mm2 and SENSE has the potential to differentiate hepatic focal lesions with improved sensitivity and specificity.

Diagnostic utility of diffusion-weighted MR imaging and apparent diffusion coefficient value for the diagnosis of adrenal tumors

PURPOSE

To determine the utility of diffusion-weighted MR imaging (DWI) for the diagnosis of adrenal tumors.

MATERIALS AND METHODS

Forty-two patients (24 men and 18 women; age, 61.5 +/- 12.7 years old; range, 34-86 years) with 43 adrenal tumors (11 functioning cortical adenomas, 20 nonfunctioning cortical adenomas, 7 metastatic tumors, and 5 pheochromocytomas) were retrospectively investigated. DWIs were obtained by single-shot spin-echo type echo-planar imaging sequence (1.5 Tesla [T]; TR = 8000 ms, TE = 72, b-factor = 0 and 1000 s/mm(2)), and apparent diffusion coefficient (ADC) value was calculated. Chemical shift images were obtained by gradient echo sequence (TR = 161, TE = 2.38 [out-of-phase, OP] and 4.76 [in-phase, IP], FA = 60), and the signal intensity index (SII; [IP-OP]/IP *100%) was calculated.

RESULTS

There was no difference in ADC values between adenomas (1.09 +/- 0.29*10(-3) mm(2)/s; range, 0.52-1.64) and metastatic tumors (0.85 +/- 0.26*10(-3); 0.51-1.23; p = 0.14). Pheochromocytomas showed the higher mean ADC value (1.59 +/- 0.34*10(-3); 1.04-1.96) compared with those of adenomas or metastatic tumors (P < 0.05 and P < 0.005, respectively). The mean SII of adenomas (62.1 +/- 17.9%; 14.5-88.4) was significantly higher than those of pheochromocytomas (4.0 +/- 10.0%; -19.6-3.3; P < 0.005) or metastatic tumors (-1.5 +/- 11.7%; -18.3-8.2; P < 0.01). There was no correlation between ADC values and SII.

CONCLUSION

Although pheochromocytomas showed higher ADC values, we did not find that ADC value had diagnostic utility for differentiating adenomas and metastatic tumors.

Advances in breast MRI: diffusion-weighted imaging of the breast

DWI, which is less affected by the state of the background mammary gland, has sufficient capability to diagnose invasive, noninvasive, and invasive lobular carcinoma. DWI is different from conventional methods based on blood flow data and has the potential to provide useful information for the evaluation of NAC, which is considered to be insufficient at present. Having the ability to provide steady, high-resolution tissue images, DWI is expected to play an important role in future breast cancer diagnosis. DWI, however, is not a complete method of diagnosis. Limits exist in spatial resolution and problems with ADC. In consideration of these shortcomings, we need to apply DWI to clinical practice while taking advantage of its high contrast resolution.

Enhanced mass on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

PURPOSE

To evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted MR imaging (DWI) in characterization of enhanced mass on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

MATERIALS AND METHODS

We analyzed consecutive breast MR images in 270 patients; however, 13 lesions in 93 patients were excluded based on our criteria. We analyzed tumor size, shape, margin, internal mass enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators of malignancy and calculate a predictive probability for malignancy. We added the corresponding categories to these prediction probabilities for malignancy and calculated diagnostic accuracy when we consider category 4b, 4c, and 5 lesions as malignant and category 4a, 3, and 2 lesions as benign. In a validation study, 75 enhancing lesions in 71 patients were examined consecutively.

RESULTS

Irregular margin, heterogeneous internal enhancement, rim enhancement, plateau time-intensity curve (TIC) pattern, and washout TIC pattern were the strongest indicators of malignancy as well as past studies, and ADC values less than 1.1x10(-3) mm2/s were also the strongest indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 92% (56/61), 86% (12/14), 97% (56/58), 71% (12/17), and 91% (68/75), respectively.

CONCLUSION

The combination of DWI and DCE-MRI could produce high diagnostic accuracy in the characterization of enhanced mass on breast MR imaging.

The value of diffusion-weighted imaging in assessing the ADC changes of tissues adjacent to breast carcinoma

Background

To define a threshold value of apparent diffusion coefficient (ADC) with which malignant breast lesions can be distinguished from benign lesions, and to evaluate the ADC change of peri-tumor tissue in breast carcinoma by echo planar-diffusion weighted imaging (EPI-DWI).

Methods

57 breast lesions were scanned by routine MRI and EPI-DWI. The ADC values were compared between malignant and benign lesions. The sensitivity and specificity of EPI-DWI and the threshold ADC value were evaluated by Receiver Operating Characteristic curve (ROC). The ADC values of malignant lesion and layered peri-tumor tissues (from innermost layer 1 to outermost layer 4 with 5 mm every layer) in different directions were compared and the ADC values among different layers were compared.

Results

The ADC value of 35 malignant lesions was statistically lower than that of 22 benign lesions (P < 0.05). In ROC curve, the threshold value was 1.24 +/- 0.25*10E-3 mm²/s (b = 500) or 1.20 +/- 0.25*10E-3 mm²/s (b = 1000). The ADC value of malignant lesions was statistically lower than that of peri-tumor tissues in different directions (P < 0.05). For peri-tumor tissues, the ADC values increased gradually from layer 1 to layer 4 and there was a significant difference between the ADC values of layer 1 and layer 2 (P < 0.05); while from layer 2 outwards, there was no statistical difference among different layers.

Conclusion

ADC value was a sensitive and specific parameter that could help to differentiate benign and malignant breast lesions. ADC changes in tissues adjacent to breast carcinoma could be detected by EPI-DWI, which made EPI-DWI a promising method for helping to determine surgical scope of breast carcinoma.

Longitudinal study of the assessment by MRI and diffusion-weighted imaging of tumor response in patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy

Measurements of tumor apparent diffusion coefficient (ADC), volume and diameter in assessing the response of patients with locally advanced breast cancer (LABC) (n = 56) undergoing neoadjuvant chemotherapy (NACT) at four time periods (before treatment and after three cycles of NACT) were carried out at 1.5 T using diffusion-weighted imaging (DWI) and MRI. Ten benign tumors and 15 controls were also investigated. The MR tumor response was compared with the clinical response. Mean ADC before treatment of malignant breast tissue was significantly lower than that of controls, disease-free contralateral tissue of the patients, and benign lesions, and gradually increased during the course of NACT. Analysis of the percentage change in ADC, volume and diameter after each cycle of NACT between clinical responders and non-responders showed that the change in ADC after the first cycle was statistically significant compared with volume and diameter, indicating its potential in assessing early response. After the third cycle, the sensitivity for differentiating responders from non-responders was 89% for volume and diameter and 68% for ADC, and the respective specificities were 50%, 70% and 100%. A sensitivity of 84% (specificity of 60% with an accuracy of 76%) was achieved when all three variables were taken together to predict the response. A cut-off value of ADC was also calculated using receiver operator characteristics analysis to discriminate between normal, benign and malignant breast tissue. Similarly, a cut-off value for ADC, volume and diameter was obtained after the second and third cycles of NACT to predict tumor response. The results show that ADC is more useful for predicting early tumor response to NACT than morphological variables, suggesting its potential in effective treatment management.

Recent advances in breast MRI and MRS

Breast MRI is an area of intense research and is fast becoming an important tool for the diagnosis of breast cancer. This review covers recent advances in breast MRI, MRS, and image post-processing and analysis. Several studies have explored a multi-parametric approach to breast imaging that combines analysis of traditional contrast enhancement patterns and lesion architecture with novel methods such as diffusion, perfusion, and spectroscopy to increase the specificity of breast MRI studies. Diffusion-weighted MRI shows some potential for increasing the specificity of breast lesion diagnosis and is even more promise for monitoring early response to therapy. MRS also has great potential for increasing specificity and for therapeutic monitoring. A limited number of studies have evaluated perfusion imaging based on first-pass contrast bolus tracking, and these clearly identify that vascular indices have great potential to increase specificity. The review also covers the relatively new acquisition technique of MR elastography for breast lesion characterization. A brief survey of image processing algorithms tailored for breast MR, including registration of serial dynamic images, segmentation and extraction of morphological features of breast lesions, and contrast uptake modeling, is also included. Recent advances in MRI, MRS, and automated image analysis have increased the utility of breast MR in diagnosis, screening, management, and therapy monitoring of breast cancer.

Monitoring response to chemotherapy of non-Hodgkin's lymphoma xenografts by T(2)-weighted and diffusion-weighted MRI

An effective method for in vivo detection of early therapeutic response of patients with non-Hodgkin's lymphoma would enable personalized clinical management of cancer therapy and facilitate the design of optimal treatment regimens. This study evaluates the feasibility of T(2)-weighted MRI (T2WI) and diffusion-weighted MRI (DWI) for in vivo detection of response of human diffuse large B-cell lymphoma xenografts in severe combined immunodeficient mice to chemotherapy. Each cycle of combination chemotherapy with cyclophosphamide, hydroxydoxorubicin, Oncovin, prednisone, and bryostatin 1 (CHOPB) was administered to tumor-carrying mice weekly for up to four cycles. T2WI and DWI were performed before the initiation of CHOPB and after each cycle of CHOPB. In order to corroborate the MRI results, histological analyses were carried out on control tumors and treated tumors after completion of all MRI studies. DWI revealed a significant (P < 0.03) increase in the mean apparent diffusion coefficient in CHOPB-treated tumors as early as 1 week after initiation of CHOPB. However, a significant (P < 0.03) decrease in mean T(2) was observed only after two cycles of CHOPB. Both MRI methods produced high-resolution (0.1 x 0.1 x 1.0 mm(3)) maps of regional therapeutic response in the treated tumors based on local apparent diffusion coefficient and T(2). Only a specific region of the tumors (in 3 of the 5 tumors) corresponding to about one third of the tumor volume exhibited a response-associate increase in ADC and decrease in T(2). An adjacent region exhibited an increase in T(2) and no change in ADC. The rest of the tumor was indistinguishable from sham-treated controls by MRI criteria. The therapeutic response of the treated tumors detected by MRI was accompanied by changes in tumor cell density, proliferation and apoptosis revealed by histological studies performed upon completion of the longitudinal study. The mechanism producing the regional response of the tumor remains to be elucidated.

Apparent diffusion coefficients of breast tumors: clinical application

PURPOSE

To evaluate the usefulness of apparent diffusion coefficient (ADC) for the differential diagnosis of breast tumors and to determine the relation between ADC and tumor cellularity.

MATERIALS AND METHODS

One hundred and thirty-six female patients (age range, 17-83 years; average age, 51.7 years) with 140 histologically proven breast tumors underwent diffusion-weighted magnetic resonance (MR) imaging (DWI) using the spin-echo echo-planar technique, and the ADCs of the tumors were calculated using 3 different b values, 0, 500, and 1000 s/mm(2). The diagnoses consisted of fibroadenoma (FA, n=16), invasive ductal carcinoma, not otherwise specified (IDC, n=117), medullary carcinoma (ME, n=3) and mucinous carcinoma (MU, n=4). Tumor cellularity was calculated from surgical specimens. The ADCs of breast tumors and cellularity were compared between different histological types by analysis of variance and Scheffe's post hoc test. The correlation between tumor cellularity and ADC was analyzed by Pearson correlation test.

RESULTS

Significant differences were observed in ADCs between FA and all types of cancers (P<0.05) and between MU and other types of cancers (P<0.01) and in cellularity between FA and cancers except MU (P<0.01) and between MU and other types of cancers (P<0.01). There was an inverse correlation between ADC and tumor cellularity (P<0.01, r(2)=0.451).

CONCLUSIONS

The ADC may potentially help in differentiating benign and malignant breast tumors. Tumor ADC correlates inversely with tumor cellularity.

Relation between cancer cellularity and apparent diffusion coefficient values using diffusion-weighted magnetic resonance imaging in breast cancer

PURPOSE

The purpose of this study was to examine the relation between cancer cellularity and the apparent diffusion coefficient (ADC) value using diffusion-weighted magnetic resonance imaging in breast cancer.

MATERIALS AND METHODS

The subjects were 27 women who had undergone operation for breast cancer. There were 27 breast cancer lesions, 24 of which were invasive ductal carcinoma (IDC) and 3 of which were noninvasive ductal carcinoma (NIDC).

RESULTS

The mean ADC values of IDC, NIDC, and normal breasts were 1.07 +/- 0.19 .10(-3), 1.42 +/- 0.17 .10(-3), and 1.96 +/- 0.21 .10(-3) mm(2)/s, respectively. The mean ADC values of IDC and NIDC were significantly different from that of normal breasts (P < 0.001 each). The mean ADC values were also significantly different between IDC and NIDC (P < 0.001). There was no correlation between the ADC value and cancer cellularity.

CONCLUSION

The mean ADC values for breast cancer were significantly different from that of normal breasts. The mean ADC value for breast cancer did not significantly correlate with cancer cellularity but did correlate with histological types.

Technology insight: water diffusion MRI--a potential new biomarker of response to cancer therapy

Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that displays information about the extent and direction of random water motion in tissues. Water movement in tissues is modified by interactions with hydrophobic cellular membranes, intracellular organelles and macromolecules. DW-MRI provides information on extracellular-space tortuosity, tissue cellularity and the integrity of cellular membranes. Images can be sensitive to large or small displacements of water, therefore, macroscopic water flows and microscopic water displacements in the extracellular space can be depicted. Preclinical and clinical data indicate a number of potential roles of DW-MRI in the characterization of malignancy, including determination of lesion aggressiveness and monitoring response to therapy. This Review outlines the biological basis of observations made on DW-MRI and describes how measurements are acquired and quantified, and discusses the interpretation of images and limitations of the technique. The strength of evidence for adoption of DW-MRI as a biomarker for the assessment of tumor response is presented.

Comparison of 3.0-and 1.5-tesla diffusion-weighted imaging in the visibility of breast cancer

PURPOSE

The aim of this study was to compare diffusion-weighted imaging (DWI) at 3.0 T and 1.5 T by evaluating the apparent diffusion coefficient (ADC) value and visibility of breast cancer in the same patients.

MATERIALS AND METHODS

A total of 13 patients (16 lesions) with breast cancer underwent DWI at 3.0 T and 1.5 T. Tumors were classified into two groups based on the lesion size. The ADC values were measured, and visibility of the tumors was scored blindly.

RESULTS

No significant difference was found for ADC values between 3.0 T and 1.5 T in either group (P > 0.05). All of the large lesions were visible clearly at both magnetic field strengths, and image scores were not different (P > 0.05). In contrast, small lesions were more clearly visible and had better image scores at 3.0 T than at 1.5 T (P < 0.001).

CONCLUSION

Small cancers were more clearly visible on DWI at 3.0 T than 1.5 T.

Optimization of b value in diffusion-weighted MRI for the differential diagnosis of benign and malignant vertebral fractures

OBJECTIVE

The objective was to explore the optimal b value in diffusion-weighted imaging (DWI) of MRI for differential diagnosis of benign and malignant vertebral fractures.

MATERIALS AND METHODS

Thirty-four consecutive patients with vertebral compression fractures underwent sagittal diffusion-weighted imaging (DWI) with different b values. The group included 14 patients with 18 benign vertebral fractures due to osteoporosis and/or trauma and 20 patients with 27 malignant vertebral fractures due to malignancy. The quality of the images was analyzed qualitatively on a three-point scale and quantitatively by measurement of the signal-to-noise ratio (SNR). Apparent diffusion coefficient (ADC) values were also calculated.

RESULTS

Smaller b values correlated with better DW image quality. We found significant differences in the qualitative points values among the DW images with different b values (F=302.18, p<0.001). The mean SNR of the images ranged from 21.75+/-3.64 at a b value of 0 s/mm2 to 5.31+/-3.17 at a b value of 800 s/mm2. The SNR of DWI with a b value of 300 s/mm2 (18.62+/-2.47) was significantly different from that with other b values (p<0.01). The mean combined ADC values of malignant fractures were significantly lower than those of benign ones on DWI with a b value of 300 s/mm2 (t=9.097, p<0.01). Four cases of benign vertebral fractures were misdiagnosed as being malignant when b values of 0 s/mm2 and 100 s/mm2 were used.

CONCLUSIONS

When DWI with multiple b values is used to differentiate benign from malignant vertebral compression fractures, b values within the range of around 300 s/mm2 are recommended, taking into account both SNR and diffusion weighting of water molecules.

Hepatic pseudo-anisotropy: a specific artifact in hepatic diffusion-weighted images obtained with respiratory triggering

PURPOSE

Hepatic pseudo-anisotropy is an artifact observed in hepatic diffusion-weighted imaging under respiratory triggering (RT-DWI). To determine the clinical significance of this phenomenon, hepatic RT-DW images were reviewed.

METHODS

One hundred and five MR examinations, including RT-DWI, were assessed. The patient group included 62 non-cirrhotic and 43 cirrhotic individuals. All images were evaluated by mutual agreement of two radiologists from the viewpoints of incidence of pseudo-anisotropy and correlation between pseudo-anisotropy and the quality of trace images. The ADC of normal hepatic parenchyma of non-cirrhotic livers were measured in both areas with and without pseudo-anisotropy.

RESULTS

Pseudo-anisotropy was observed in 60% of non-cirrhotic (37/62) and 30% of cirrhotic (13/43) images. The difference between the two groups was statistically significant (P < 0.001). The quality of trace images showed a tendency to worsen as pseudo-anisotropy became significant. However, the quality of trace images was generally satisfactory, with only two patients whose trace images were difficult to interpret due to pseudo-anisotropy. The areas with pseudo-anisotropy showed higher ADC than those without pseudo-anisotropy (P < 0.001).

CONCLUSION

Pseudo-anisotropy is a type of artifact that originates from respiratory movement. Even though respiratory triggering is employed, ADC measurement of the liver is inaccurate because of pseudo-anisotropy, especially in non-cirrhotic patients.

Diffusion weighted imaging in breast MRI: comparison of two different pulse sequences

RATIONALE AND OBJECTIVES

Comparison of two different diffusion weighted (DW) sequences in breast MRI regarding the differentiation between benign and malignant lesions.

MATERIALS AND METHODS

Breast MRI including two different DW sequences was performed in 165 consecutive women. Inclusion criteria for DW imaging and ADC evaluation were histologically proven focal mass lesions with a diameter of more than 5 mm in dynamic contrast-enhanced MRI. The DW sequences were pre-contrast echo-planar imaging with spectral fat saturation (EPI fs) and DW EPI with inversion recovery (EPI STIR) (b-values: 50, 400, and 800). Lesions were analyzed regarding visibility in DW sequences and ADC values.

RESULTS

Inclusion criteria were fulfilled in 56 women with 69 lesions. Five lesions could not be evaluated for different reasons. Finally, DW sequences were evaluated in 51 women with 64 focal mass lesions (15 benign, 49 malignant). The visibility of the lesions was significantly better in the EPI fs sequence (P<0.05). The ADC values (10(-3) mm(2)/s) in the EPI fs were 1.76, 2.58, and 1.21 (mean, maximum, minimum, respectively) for benign lesions and 0.90, 1.19, and 0.34 for malignant lesions. Respective values in the EPI STIR sequence were 1.92, 3.20, 1.10, and 0.91, 1.43, 0.35. Only in the EPI fs sequence there was no overlap in ADC values between benign and malignant lesions.

CONCLUSION

The DW MRI of the breast with EPI fs and EPI STIR sequences has a high potential to differentiate between benign and malignant breast lesions. Due to better lesion visibility and selectivity, the EPI fs sequence should be preferred.

Comparison of breast cancer detection by diffusion-weighted magnetic resonance imaging and mammography

PURPOSE

Breast cancer-detecting ability of diffusion-weighted magnetic resonance imaging (DW-MRI) was investigated by comparing the breast cancer detection rates of DW-MRI and mammography (MMG).

MATERIALS AND METHODS

The subjects were 48 women who had breast cancer (53 cancer lesions) who underwent DW-MRI before surgery. Altogether, 41 lesions were invasive ductal carcinoma (IDC), 7 were noninvasive ductal carcinoma (NIDC) and 5 were "others."

RESULTS

The breast cancer detection rates by MMG and DW-MRI were 84.9% and 94.3% (P < 0.001), respectively. In each classification of histology and size, the detection rate by DW-MRI was higher than that by MMG. In relation to the mammary gland density, the detection rates of fatty, scattered, heterogeneously dense, and extremely dense mammary glands were 100%, 100%, 92.0%, and 83.3%, respectively. The mean apparent diffusion coefficient values of the histologic types were 1.07 +/- 0.17 x 10(-3), 1.50 +/- 0.24 x 10(-3), 1.12 +/- 0.25 x 10(-3), and 2.01 +/- 0.29 x 10(-3) mm(2)/s for IDC, NIDC, others, and normal breast, respectively, showing that the values of IDC and NIDC were significantly different from that of the normal breast (P < 0.001 each). A significant difference was also noted between IDC and NIDC (P < 0.001).

CONCLUSION

DW-MRI may be useful for detecting breast cancer in a wide age group of women, including young women with dense mammary glands.

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.

Prostate cancer screening: the clinical value of diffusion-weighted imaging and dynamic MR imaging in combination with T2-weighted imaging

PURPOSE

To evaluate the clinical value of diffusion-weighted imaging (DWI) and dynamic MRI in combination with T2-weighted imaging (T2W) for the detection of prostate cancer.

MATERIALS AND METHODS

A total of 83 patients with elevated serum prostate specific antigen (PSA) levels (>4.0 ng/mL) were evaluated by T2W, DWI, and dynamic MRI at 1.5 T prior to needle biopsy. The data from the results of the T2W alone (protocol A), combination of T2W and DWI (protocol B), and the combination of T2W+DWI and dynamic MRI (protocol C) were entered into a receiver operating characteristic (ROC) curve analysis, under results of systemic biopsy as the standard of reference.

RESULTS

Prostate cancer was pathologically detected in 44 of the 83 patients. The sensitivity, specificity, accuracy, and the area under the ROC curve (Az) for the detection of prostate cancer were as follows: 73%, 54%, 64%, and 0.711, respectively, in protocol A; 84%, 85%, 84%, and 0.905, respectively, in protocol B; and 95%, 74%, 86%, and 0.966, respectively, in protocol C. The sensitivity, specificity, and accuracy were significantly different between the three protocols (P < 0.01).

CONCLUSION

In patients with elevated serum PSA levels, the combination of T2W, DWI, and dynamic MRI may be a valuable tool for detecting prostate cancer and avoiding an unnecessary biopsy without missing prostate cancer.

The effect of simultaneous use of respiratory triggering in diffusion-weighted imaging of the liver

OBJECTIVE

To determine the effect of simultaneous use of respiratory triggering in hepatic diffusion-weighted imaging (DWI), we compared DWI with respiratory triggering (RT-DWI) and DWI under free breathing (FB-DWI) in terms of relative contrast between hepatic tumor and surrounding liver parenchyma, apparent diffusion coefficient (ADC) measurement, and frequency of respiratory misregistration.

MATERIALS AND METHODS

Thirty patients (21 men, 9 women, aged 25 to 80 years) with liver metastasis or hepatocellular carcinoma in the right hepatic lobe were examined with RT- and FB-DWI. In patients having multiple tumors, up to 3 lesions were selected by mutual agreement of 2 diagnostic radiologists. Finally, 59 nodules were selected for evaluation. Relative contrast ratio (RCR) between the lesions and surrounding parenchyma and ADC were measured in each hepatic lesion in each sequence. The differences in RCR and ADC between RT- and FB-DWI were statistically analyzed using Wilcoxon's signed rank test. The frequency of respiratory misregistration advents in each sequence was visually evaluated by the 2 diagnostic radiologists and assessed using McNemar's test.

RESULTS

RCRs were significantly higher in RT- than in FB-DWI (P<0.001). The difference in ADC between the 2 sequences was not significant. However, ADCs tended to be more scattered in FB- than in RT-DWI. The frequency of respiratory misregistration advents was significantly higher in FB- than in RT-DWI.

CONCLUSION

FB- was inferior to RT-DWI in both contrast between tumors and surrounding liver parenchyma and in accuracy of ADC measurement as far as the numbers of excitation in each sequence were the same. For preoperative examination of hepatic resection, RT- is more suitable than FB-DWI.

Detecting Breast Cancer with Non-contrast MR Imaging: Combining Diffusion-weighted and STIR Imaging

We combined diffusion-weighted (DWI) and short TI inversion recovery (STIR) imaging to evaluate the diagnostic capability of non-contrast magnetic resonance (MR) imaging to detect breast cancer. Seventy women patients underwent mammography and MR imaging with combined DWI (b factor: 1000) and STIR that revealed malignancy, and postoperative pathological examination confirmed breast cancer. Interpreted images were evaluated for sensitivity, false negative rate (FN), sensitivity by pT, and sensitivity by background density of the mammary gland. Of the 70 cases, 68 were diagnosed as cancer by DWI and STIR (sensitivity, 97% [68/70]; FN, 2.9% [2/70]). Sensitivities by pT were: pTis, 67% (4/6); pT1, 100% (33/33); and pT2-4, 100% (31/31). No significant differences were observed in sensitivity between pT1 and pT2-4 (P<0.001). Sensitivities by background density of mammary gland were: fatty/scattered fibroglandular tissue, 95% (20/21) and heterogeneous fibroglandular tissue/mostly fibroglandular tissue, 98% (48/49). No significant differences were observed (P<0.001). Two cases, an intraductal and an apocrine carcinoma, were incorrectly diagnosed by MR imaging. Precise diagnosis of breast cancer is possible with combined DWI and STIR, even in non-contrast MR imaging, regardless of the diameter or background density of mammary gland. It is hoped that non-contrast MR imaging that combines DWI and STIR will become an established clinical screening method.