Dissected sentinel lymph nodes of breast cancer patients: characterization with high-spatial-resolution 7-T MR imaging

The Role of MRI in Breast Cancer and Breast Conservation Therapy

Contrast-enhanced breast MRI has an established role in aiding in the detection, evaluation, and management of breast cancer. This article discusses MRI sequences, the clinical utility of MRI, and how MRI has been evaluated for use in breast radiotherapy treatment planning. We highlight the contribution of MRI in the decision-making regarding selecting appropriate candidates for breast conservation therapy and review the emerging role of MRI-guided breast radiotherapy.

Comparison of Axillary Lymph Nodes on Breast MRI Before and After COVID-19 Booster Vaccination

RATIONALE AND OBJECTIVES

Vaccine-related lymphadenopathy is a frequent finding following initial coronavirus disease 2019 (COVID-19) vaccination, but the frequency after COVID-19 booster vaccination is still unknown. In this study we compare axillary lymph node morphology on breast MRI before and after COVID-19 booster vaccination.

MATERIALS AND METHODS

This retrospective, single-center, IRB-approved study included patients who underwent breast MRI between October 2021 and December 2021 after the COVID-19 booster vaccination. The axillary lymph node with the greatest cortical thickness ipsilateral to the side of vaccination was measured on MRI after booster vaccination and before initial COVID-19 vaccination. Comparisons were made between patients with and without increase in cortical thickness of ≥ 0.2 cm. Continuous covariates were compared using Wilcoxon rank-sum test and categorical covariates were compared using Fisher's exact test. Multiple comparison adjustment was made using the Benjamini-Hochberg procedure.

RESULTS

All 128 patients were included. Twenty-four of 128 (19%) displayed an increase in lymph node cortical thickness of ≥ 0.2 cm. Patients who received the booster more recently were more likely to present cortical thickening, with a median of 9 days (IQR 5, 20) vs. 36 days (IQR 18, 59) (p < 0.001). Age (p = 0.5) and type of vaccine (p = 0.7) were not associated with thickening. No ipsilateral breast cancer or malignant lymphadenopathy were diagnosed on follow-up.

CONCLUSION

Axillary lymphadenopathy on breast MRI following COVID-19 booster vaccination is a frequent finding, especially in the first 3 weeks after vaccination. Additional evaluation or follow-up may be omitted in patients with low concern for malignancy.

Magnetic resonance imaging evaluation of single axillary lymph node metastasis in breast cancer: Emphasis on the location of lymph nodes

To evaluate the frequency and location of abnormal lymph nodes (LNs) in breast cancer patients with a single axillary lymph node (ALN) metastasis on breast magnetic resonance imaging (MRI). We retrospectively reviewed the MRI findings of 219 consecutive patients with breast cancer with single ALN metastasis who were surgically confirmed at our institution between January 2018 and December 2018. The morphological features and locations of the abnormal LN on MRI were analyzed. Pathology reports were reviewed to evaluate the size of the metastases and whether they were sentinel LNs (SLNs). Of the 219 patients with a single ALN metastasis, 56 (25.6%) showed abnormal MRI findings. Of these, 54 (96.4%) had either the lowest or second-lowest LN in the level I axilla. In 184 (91.5%) of 201 patients who underwent SLN biopsy, the metastatic LN were SLN. Macrometastases were found more frequently in cases with abnormal LNs than in those with normal-looking LNs (P = .004). The most frequent morphological feature of metastatic ALNs was a diffuse cortical thickening of 3 to 5 mm (37.5%). Although MRI findings of single ALN metastasis in breast cancer patients are none or minimal, abnormalities are observed in the lowest or second-lowest LN in the lower axilla when present, suggesting the location of the SLNs.

R2* value derived from multi-echo Dixon technique can aid discrimination between benign and malignant focal liver lesions

BACKGROUND

R2* estimation reflects the paramagnetism of the tumor tissue, which may be used to differentiate between benign and malignant liver lesions when contrast agents are contraindicated.

AIM

To investigate whether R2* derived from multi-echo Dixon imaging can aid differentiating benign from malignant focal liver lesions (FLLs) and the impact of 2D region of interest (2D-ROI) and volume of interest (VOI) on the outcomes.

METHODS

We retrospectively enrolled 73 patients with 108 benign or malignant FLLs. All patients underwent conventional abdominal magnetic resonance imaging and multi-echo Dixon imaging. Two radiologists independently measured the mean R2* values of lesions using 2D-ROI and VOI approaches. The Bland–Altman plot was used to determine the interobserver agreement between R2* measurements. Intraclass correlation coefficient (ICC) was used to determine the reliability between the two readers. Mean R2* values were compared between benign and malignant FFLs using the nonparametric Mann–Whitney test. Receiver operating characteristic curve analysis was used to determine the diagnostic performance of R2* in differentiation between benign and malignant FFLs. We compared the diagnostic performance of R2* measured by 2D-ROI and VOI approaches.

RESULTS

This study included 30 benign and 78 malignant FLLs. The interobserver reproducibility of R2* measurements was excellent for the 2D-ROI (ICC = 0.994) and VOI (ICC = 0.998) methods. Bland–Altman analysis also demonstrated excellent agreement. Mean R2* was significantly higher for malignant than benign FFLs as measured by 2D-ROI (P < 0.001) and VOI (P < 0.001). The area under the curve (AUC) of R2* measured by 2D-ROI was 0.884 at a cut-off of 25.2/s, with a sensitivity of 84.6% and specificity of 80.0% for differentiating benign from malignant FFLs. R2* measured by VOI yielded an AUC of 0.875 at a cut-off of 26.7/s in distinguishing benign from malignant FFLs, with a sensitivity of 85.9% and specificity of 76.7%. The AUCs of R2* were not significantly different between the 2D-ROI and VOI methods.

CONCLUSION

R2* derived from multi-echo Dixon imaging whether by 2D-ROI or VOI can aid in differentiation between benign and malignant FLLs.

Prediction of axillary nodal burden in patients with invasive lobular carcinoma using MRI

PURPOSE

To investigate clinical and imaging features associated with a high nodal burden (≥ 3 metastatic lymph nodes [LNs]) and compare diagnostic performance of US and MRI in patients with invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC).

METHODS

Retrospective search revealed 239 patients with ILC and 999 with IDC who underwent preoperative US and MRI between January 2016 and June 2019. Patients with ILC were propensity-score-matched with patients with IDC. Univariate and multivariate logistic regression analyses were performed to determine factors associated with ≥ 3 metastatic LNs.

RESULTS

412 patients (206 ILC and 206 IDC) were evaluated. Of all patients with ILC, 27.2% (56/206) were node-positive and 7.8% (16/206) showed a high nodal burden. In multivariate analysis, the clinical N stage was the only independent factor associated with a high nodal burden in patients with IDC (odds ratio [OR] 6.24; 95% confidence interval [CI] 1.57-24.73; P = 0.009), but not in patients with ILC. Increased cortical thickness with loss of fatty hilum on US was associated with a high nodal burden in patients with ILC (OR 58.40; 95% CI 5.09-669.71; P = 0.001) and IDC (OR 24.14; 95% CI 3.52-165.37; P = 0.001), while suspicious LN findings at MRI were independently associated with a high nodal burden in ILC only (OR 13.94; 95% CI 2.61-74.39; P = 0.002).

CONCLUSION

In patients with ILC, MRI findings of suspicious LNs were helpful to predict a high nodal disease burden.

Magnetic resonance imaging and bioimpedance evaluation of lymphatic abnormalities in patients with breast cancer treatment-related lymphedema

PURPOSE

Breast cancer treatment-related lymphedema (BCRL) evaluation is frequently performed using portable measures of limb volume and bioimpedance asymmetry. Here quantitative magnetic resonance imaging (MRI) is applied to evaluate deep and superficial tissue impairment, in both surgical and contralateral quadrants, to test the hypothesis that BCRL impairment is frequently bilateral and extends beyond regions commonly evaluated with portable external devices.

METHODS

3-T MRI was applied to investigate BCRL topographical impairment. Female BCRL (n = 33; age = 54.1 ± 11.2 years; stage = 1.5 ± 0.8) and healthy (n = 33; age = 49.4 ± 11.0 years) participants underwent quantitative upper limb MRI relaxometry (T₂), bioimpedance asymmetry, arm volume asymmetry, and physical evaluation. Parametric tests were applied to evaluate study measurements (i) between BCRL and healthy participants, (ii) between surgical and contralateral limbs, and (iii) in relation to clinical indicators of disease severity. Two-sided p-value < 0.05 was required for significance.

RESULTS

Bioimpedance asymmetry was significantly correlated with MRI-measured water relaxation (T₂) in superficial tissue. Deep muscle (T₂ = 37.6 ± 3.5 ms) and superficial tissue (T₂ = 49.8 ± 13.2 ms) relaxation times were symmetric in healthy participants. In the surgical limbs of BCRL participants, deep muscle (T₂ = 40.5 ± 4.9 ms) and superficial tissue (T₂ = 56.0 ± 14.8 ms) relaxation times were elevated compared to healthy participants, consistent with an edematous micro-environment. This elevation was also observed in contralateral limbs of BCRL participants (deep muscle T₂ = 40.3 ± 5.7 ms; superficial T₂ = 56.6 ± 13.8 ms).

CONCLUSIONS

Regional MRI measures substantiate a growing literature speculating that superficial and deep tissue, in surgical and contralateral quadrants, is affected in BCRL. The implications of these findings in the context of titrating treatment regimens and understanding malignancy recurrence are discussed.

Imaging-Based Approach to Axillary Lymph Node Staging and Sentinel Lymph Node Biopsy in Patients With Breast Cancer

OBJECTIVE. This review provides historical and current data to support the role of imaging-based axillary lymph node staging and sentinel lymph node biopsy as the standard of care for axillary management in women with a diagnosis of breast cancer, before and after neoadjuvant systemic therapy. CONCLUSION. The implications of surgical trials (American College of Surgeons Oncology Group [ACOSOG] Z011 and ACOSOG Z1071) on imaging protocols for the axilla are reviewed, in conjunction with the American Joint Committee on Cancer nodal staging guidelines.

MRI evaluation of axillary and intramammary lymph nodes in the postoperative period

Our study aimed to evaluate if breast‐conserving surgery and adjuvant treatment could affect the morphological features of axillary and intramammary lymph nodes on magnetic resonance imaging (MRI) in patients with invasive breast cancer and clinically negative axilla. In this single‐center study, we retrospectively evaluated 50 patients who had (a) breast‐conserving surgery, (b) clinically negative axilla, (c) preoperative MRI within 3 months before surgery, and (d) postoperative MRI within 12 months after surgery. Axillary and intramammary lymph nodes on postoperative MRI were identified and then compared with preoperative MRI by two breast radiologists with regards to the following: enlargement, cortical thickening, presence of fatty hilum, irregularity, heterogeneity, matting, and axillary lymph node asymmetry. Three hundred and two axillary and eight intramammary lymph nodes were evaluated. Enlargement and cortical thickening were seen in 5/50 (10%) patients in three axillary and two intramammary lymph nodes. None of the lymph nodes on postoperative MRI demonstrated occurrence of lack of fatty hilum, irregularity, heterogeneity, matting or axillary lymph node asymmetry. No evidence of recurrence was observed on 2‐year follow‐up. Lymph node enlargement and cortical thickening may be observed in a few patients in the postoperative period. Nevertheless, in patients with clinically negative axilla, these changes in morphology are often related to treatment rather than malignancy and favor short‐term follow‐up as an alternative to lymph node biopsy.

Susceptibility Perturbation MRI Maps Tumor Infiltration into Mesorectal Lymph Nodes

Noninvasive characterization of lymph node involvement in cancer is an enduring onerous challenge. In rectal cancer, pathologic lymph node status constitutes the most important determinant of local recurrence and overall survival, and patients with involved lymph nodes may benefit from preoperative chemo and/or radiotherapy. However, knowledge of lymph node status before surgery is currently hampered by limited imaging accuracy. Here, we introduce Susceptibility-Perturbation MRI (SPI) as a novel source of contrast to map malignant infiltration into mesorectal lymph nodes. SPI involves multigradient echo (MGE) signal decays presenting a nonmonoexponential nature, which we show is sensitive to the underlying microstructure via susceptibility perturbations. Using numerical simulations, we predicted that the large cell morphology and the high cellularity of tumor within affected mesorectal lymph nodes would induce signature SPI decays. We validated this prediction in mesorectal lymph nodes excised from total mesorectal excision specimens of patients with rectal cancer using ultrahigh field (16.4 T) MRI. SPI signals distinguished benign from malignant nodal tissue, both qualitatively and quantitatively, and our histologic analyses confirmed cellularity and cell size were the likely underlying sources for the differences observed. SPI was then adapted to a clinical 1.5 T scanner, added to patients' staging protocol, and compared with conventional assessment by two expert radiologists. Nonmonoexponential decays, similar to those observed in the ex vivo study, were demonstrated, and SPI classified lymph nodes more accurately than standard high-resolution T₂-weighted imaging assessment. These findings suggest this simple, yet highly informative, method can improve rectal cancer patient selection for neoadjuvant therapy. SIGNIFICANCE: These findings introduce an MRI methodology tailored to detect magnetic susceptibility perturbations induced by subtle alterations in tissue microstructure.

3.0 T relaxation time measurements of human lymph nodes in adults with and without lymphatic insufficiency: Implications for magnetic resonance lymphatic imaging

The purpose of this work was to quantify 3.0 T (i) T1 and T2 relaxation times of in vivo human lymph nodes (LNs) and (ii) LN relaxometry differences between healthy LNs and LNs from patients with lymphatic insufficiency secondary to breast cancer treatment-related lymphedema (BCRL). MR relaxometry was performed over bilateral axillary regions at 3.0 T in healthy female controls (105 LNs from 20 participants) and patients with BCRL (108 LNs from 20 participants). Quantitative T1 maps were calculated using a multi-flip-angle (20, 40, 60°) method with B1 correction (dual-TR method, TR1 /TR2  = 30/130 ms), and T2 maps using a multi-echo (TE  = 9-189 ms; 12 ms intervals) method. T1 and T2 were quantified in the LN cortex and hilum. A Mann-Whitney U-test was applied to compare LN relaxometry values between patients and controls (significance, two sided, p < 0.05). Linear regression was applied to evaluate how LN relaxometry varied with age, BMI, and clinical indicators of disease. LN substructure relaxation times (mean ± standard deviation) in healthy controls were T1 cortex, 1435 ± 391 ms; T1 hilum, 714 ± 123 ms; T2 cortex, 102 ± 12 ms, and T2 hilum, 119 ± 21 ms. T1 of the LN cortex was significantly reduced in the contralateral axilla of BCRL patients compared with the axilla on the surgical side (p < 0.001) and compared with bilateral control values (p < 0.01). The LN cortex T1 asymmetry discriminated cases from controls (p = 0.004) in a multiple linear regression, accounting for age and BMI. Human 3.0 T T1 and T2 relaxation times in axillary LNs were quantified for the first time in vivo. Measured values are relevant for optimizing acquisition parameters in anatomical lymphatic imaging sequences, and can serve as a reference for novel functional and molecular LN imaging methods that require quantitative knowledge of LN relaxation times.

Axillary Sentinel Lymph Nodes in Breast Cancer: Quantitative Evaluation at Dual-Energy CT

Purpose To evaluate the diagnostic performance of quantitative parameters derived from dual-energy CT for the preoperative diagnosis of metastatic sentinel lymph nodes (SLNs) in participants with breast cancer. Materials and Methods For this prospective study, dual-phase contrast agent-enhanced CT was performed in female participants with breast cancer from June 2015 to December 2017. Quantitative dual-energy CT parameters and morphologic parameters were compared between metastatic and nonmetastatic SLNs. The quantitative parameters were fitted to univariable and multivariable logistic regression models. The diagnostic role of morphologic and quantitative parameters was analyzed by receiver operating characteristic curves and compared by using the McNemar test. Results This study included 193 female participants (mean age, 47.6 years ± 10.1; age range, 22-79 years). Quantitative dual-energy CT parameters including slope of the spectral Hounsfield unit curve (λ_Hu) measured at both arterial and venous phases, normalized iodine concentration at both arterial and venous phase, and normalized effective atomic number at the venous phase were higher in metastatic than in nonmetastatic SLNs (P value range, ≤.001 to .031). Univariable and multivariable logistic regression analyses showed that venous phase λ_Hu (in Hounsfield units per kiloelectron-volt) was the best single parameter for the detection of metastatic SLNs. The accuracy of the venous phase λ_Hu for detecting metastatic SLNs was 90.5% on a per-lymph node basis and 87.0% on a per-patient basis. The accuracy and specificity at venous phase λ_Hu was higher than their counterparts in the morphologic parameters (P < .001). Conclusion Dual-energy CT is a complementary means for the preoperative identification of sentinel lymph nodes metastases in participants with breast cancer. © RSNA, 2018 Online supplemental material is available for this article.

Supine MRI for regional breast radiotherapy: imaging axillary lymph nodes before and after sentinel-node biopsy

Regional radiotherapy (RT) is increasingly used in breast cancer treatment. Conventionally, computed tomography (CT) is performed for RT planning. Lymph node (LN) target levels are delineated according to anatomical boundaries. Magnetic resonance imaging (MRI) could enable individual LN delineation. The purpose was to evaluate the applicability of MRI for LN detection in supine treatment position, before and after sentinel-node biopsy (SNB). Twenty-three female breast cancer patients (cTis-3N0M0) underwent 1.5 T MRI, before and after SNB, in addition to CT. Endurance for MRI was monitored. Axillary levels were delineated. LNs were identified and delineated on MRI from before and after SNB, and on CT, and compared by Wilcoxon signed-rank tests. LN locations and LN-based volumes were related to axillary delineations and associated volumes. Although postoperative effects were visible, LN numbers on postoperative MRI (median 26 LNs) were highly reproducible compared to preoperative MRI when adding excised sentinel nodes, and higher than on CT (median 11, p  <  0.001). LN-based volumes were considerably smaller than respective axillary levels. Supine MRI of LNs is feasible and reproducible before and after SNB. This may lead to more accurate RT target definition compared to CT, with potentially lower toxicity. With the MRI techniques described here, initiation of novel MRI-guided RT strategies aiming at individual LNs could be possible.

Bilateral Changes in Deep Tissue Environment After Manual Lymphatic Drainage in Patients with Breast Cancer Treatment-Related Lymphedema

BACKGROUND

Breast cancer treatment-related lymphedema (BCRL) arises from a mechanical insufficiency following cancer therapies. Early BCRL detection and personalized intervention require an improved understanding of the physiological processes that initiate lymphatic impairment. Here, internal magnetic resonance imaging (MRI) measures of the tissue microenvironment were paired with clinical measures of tissue structure to test fundamental hypotheses regarding structural tissue and muscle changes after the commonly used therapeutic intervention of manual lymphatic drainage (MLD).

METHODS AND RESULTS

Measurements to identify lymphatic dysfunction in healthy volunteers (n = 29) and patients with BCRL (n = 16) consisted of (1) limb volume, tissue dielectric constant, and bioelectrical impedance (i.e., non-MRI measures); (2) qualitative 3 Tesla diffusion-weighted, T₁-weighted and T₂-weighted MRI; and (3) quantitative multi-echo T₂ MRI of the axilla. Measurements were repeated in patients immediately following MLD. Normative control and BCRL T₂ values were quantified and a signed Wilcoxon Rank-Sum test was applied (significance: two-sided p < 0.05). Non-MRI measures yielded significant capacity for discriminating between arms with versus without clinical signs of BCRL, yet yielded no change in response to MLD. Alternatively, a significant increase in deep tissue T₂ on the involved (pre T₂ = 0.0371 ± 0.003 seconds; post T₂ = 0.0389 ± 0.003; p = 0.029) and contralateral (pre T₂ = 0.0365 ± 0.002; post T₂ = 0.0395 ± 0.002; p < 0.01) arms was observed. Trends for larger T₂ increases on the involved side after MLD in patients with stage 2 BCRL relative to earlier stages 0 and 1 BCRL were observed, consistent with tissue composition changes in later stages of BCRL manifesting as breakdown of fibrotic tissue after MLD in the involved arm. Contrast consistent with relocation of fluid to the contralateral quadrant was observed in all stages.

CONCLUSION

Quantitative deep tissue T₂ MRI values yielded significant changes following MLD treatment, whereas non-MRI measurements did not vary. These findings highlight that internal imaging measures of tissue composition may be useful for evaluating how current and emerging therapies impact tissue function.

Lymphedema evaluation using noninvasive 3T MR lymphangiography

PURPOSE

To exploit the long 3.0T relaxation times and low flow velocity of lymphatic fluid to develop a noninvasive 3.0T lymphangiography sequence and evaluate its relevance in patients with lymphedema.

MATERIALS AND METHODS

A 3.0T turbo-spin-echo (TSE) pulse train with long echo time (TE_effective  = 600 msec; shot-duration = 13.2 msec) and TSE-factor (TSE-factor = 90) was developed and signal evolution simulated. The method was evaluated in healthy adults (n = 11) and patients with unilateral breast cancer treatment-related lymphedema (BCRL; n = 25), with a subgroup (n = 5) of BCRL participants scanned before and after manual lymphatic drainage (MLD) therapy. Maximal lymphatic vessel cross-sectional area, signal-to-noise-ratio (SNR), and results from a five-point categorical scoring system were recorded. Nonparametric tests were applied to evaluate study parameter differences between controls and patients, as well as between affected and contralateral sides in patients (significance criteria: two-sided P < 0.05).

RESULTS

Patient volunteers demonstrated larger lymphatic cross-sectional areas in the affected (arm = 12.9 ± 6.3 mm² ; torso = 17.2 ± 15.6 mm² ) vs. contralateral (arm = 9.4 ± 3.9 mm² ; torso = 9.1 ± 4.6 mm² ) side; this difference was significant both for the arm (P = 0.014) and torso (P = 0.025). Affected (arm: P = 0.010; torso: P = 0.016) but not contralateral (arm: P = 0.42; torso: P = 0.71) vessel areas were significantly elevated compared with control values. Lymphatic cross-sectional areas reduced following MLD on the affected side (pre-MLD: arm = 8.8 ± 1.8 mm² ; torso = 31.4 ± 26.0 mm² ; post-MLD: arm = 6.6 ± 1.8 mm² ; torso = 23.1 ± 24.3 mm² ). This change was significant in the torso (P = 0.036). The categorical scoring was found to be less specific for detecting lateralizing disease compared to lymphatic-vessel areas.

CONCLUSION

A 3.0T lymphangiography sequence is proposed, which allows for upper extremity lymph stasis to be detected in ∼10 minutes without exogenous contrast agents.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1349-1360.

T2* mapping combined with conventional T2-weighted image for prostate cancer detection at 3.0T MRI: a multi-observer study

BACKGROUND

T2* relaxation is a primary determinant of image contrast with Gradient echo (GRE) sequences, and it has been widely used across body regions.

PURPOSE

To compare the diagnostic performance of T2* mapping in combination with T2-weighted (T2W) imaging to T2W imaging alone for prostate cancer (PCa) detection.

MATERIAL AND METHODS

The study included 31 patients (mean age, 62 ± 3 years; age range, 45-78 years) who underwent magnetic resonance imaging (MRI) at 3.0T and histological examination. Three observers with varying experience levels reviewed T2W imaging alone, T2* mapping alone, and T2W imaging combined with T2* mapping. A five-point scale was used to assess the probability of PCa in each segment on MR images. Statistical analysis was performed using Z tests after adjusting for data clustering.

RESULTS

The area under the curve (AUC) of T2W imaging and T2* mapping data (observer 1, 0.93; observer 2, 0.90; observer 3, 0.77) was higher than T2W imaging (observer 1, 0.84; observer 2, 0.79; observer 3, 0.69) for all observers (P < 0.01 in all comparisons). The AUC of T2W imaging and T2* mapping data was higher for observers 1 and 2 than for observer 3 (P < 0.01). The sensitivity and specificity of T2W imaging and T2* mapping data (observer 1, 95%, 85%; observer 2, 90%, 83%; and observer 3, 82%, 63%, respectively) was higher than T2W imaging (observer 1, 78%, 79%; observer 2, 76%, 72%; observer 3, 74%, 51%, respectively) for all observers (P < 0.01 for observer 1; P < 0.01 for observers 2 and 3).

CONCLUSION

The addition of T2* mapping to T2W imaging improved the diagnostic performance of MRI in PCa detection.

Comparison of T2(*) mapping with diffusion-weighted imaging in the characterization of low-grade vs intermediate-grade and high-grade prostate cancer

OBJECTIVE

To evaluate the diagnostic value of T2(*) mapping compared with apparent diffusion coefficient (ADC) mapping in the characterization of low-grade (Gleason score, ≤6) vs intermediate-grade and high-grade (Gleason score ≥7) prostate cancer (PCa).

METHODS

62 patients who underwent MRI before prostatectomy were evaluated. Two readers independently scored the probabilities of tumours in 12 regions of the prostate on T2(*) and ADC images. The data were divided into two groups, i.e. low- vs intermediate- and high-grade PCa, and correlated with the histopathological results. The diagnostic performance parameters, areas under the receiver-operating characteristic curves and interreader agreements were calculated.

RESULTS

For Reader 2, ADC mapping exhibited a greater accuracy for intermediate-grade PCas than for high-grade PCas (0.77 vs 0.83, p < 0.05). For both readers, T2(*) mapping exhibited a greater accuracy for intermediate-grade PCas than for high-grade PCas (Reader 1, 0.86 vs 0.81; Reader 2, 0.83 vs 0.78; p < 0.05). The areas under the curve of T2(*) mappings were greater than those of the ADC mappings for the intermediate- and high-grade PCas (Reader 1, 0.83 vs 0.78; Reader 2, 0.80 vs 0.75; p < 0.05) but not for the low-grade PCas (Reader 1, 0.86 vs 0.84; Reader 2, 0.83 vs 0.82; p > 0.05). The weighted κ value of T2(*) mapping was 0.59.

CONCLUSION

T2(*) mapping improves the accuracy of the characterization of intermediate- and high-grade PCas but not low-grade PCas compared with ADC mapping.

ADVANCES IN KNOWLEDGE

T2(*) mapping exhibited greater diagnostic accuracy than ADC mapping in the characterization of intermediate- and high-grade PCas. T2(*) mapping exhibited limited value in the characterization of low-grade PCa.

Meta analysis of lymph node metastasis of breast cancer patients: Clinical value of DWI and ADC value

OBJECTIVES

To evaluate the diagnostic utility of DWI in the assessment of node metastases and investigate whether the ADC value could be used to discriminate between metastatic and non-metastatic lymph nodes in breast cancer patients.

MATERIALS AND METHODS

13 studies with a total of 676 metastatic and 811 non-metastatic lymph nodes were included.

RESULTS

(1) The pooled sensitivity, specificity, PPV and NPV of DWI were 0.83, 0.82, 0.83 and 0.85, respectively. The PLR and NLR were 4.95 and 0.23, respectively. The AUC and Q* index were 0.91 and 0.85, respectively. (2) The ADC value of metastatic lymph nodes was lower than non-metastatic lymph nodes (WMD=-0.213, 95% CI -0.349 to -0.076, Z=3.05, P<0.05). (3) Subgroup meta-analysis of the group of b(0800): The pooled sensitivity, specificity, PPV and NPV of DWI were 0.86, 0.86, 0.82 and 0.90, respectively. The PLR and NLR were 6.76 and 0.18, respectively. The AUC and Q* index were 0.93 and 0.87. The ADC value of metastatic lymph nodes was lower than non-metastatic lymph nodes(WMD=-0.267, 95% CI -0.348 to -0.185, Z=6.40, P<0.05).

CONCLUSIONS

DWI and ADC value appear to be a reliable method to differentiate metastatic and non-metastatic lymph nodes. The combination of b=0 and 800s/mm(2) resulted in higher diagnostic accuracy and more pronounced ADC value difference. If only a couple of b values are used, those of b=0 and 800s/mm(2) are recommended.

T2* relaxation time in the detection and assessment of aggressiveness of peripheral zone cancer in comparison with diffusion-weighted imaging

AIM

To investigate the feasibility of T2* relaxation time for distinguishing benign from malignant regions, as well as tumour aggressiveness, within the peripheral zone (PZ) of the prostate in comparison with diffusion-weighted imaging (DWI).

MATERIALS AND METHODS

Fifty-eight patients with prostate cancer underwent 3 T magnetic resonance imaging using multi-echo T2* and DWI (maximum b-value, 2000 s/mm(2)). Parametric maps were obtained for apparent diffusion coefficient (ADC) and T2* values. Two radiologists reviewed these maps and measured ADC and T2* values in sextants positive for cancer at biopsy. Data were analysed using mixed-model analysis of variance and receiver operating characteristic curves.

RESULTS

Ninety-three sextants exhibited a Gleason score of 6; 59 exhibited a Gleason score of 7 or 8. The T2* value was significantly lower in cancerous sextants than in the benign PZ (48.69+0.60 versus 74.14+0.56, p<0.001), as well as in cancerous sextants with higher rather than lower Gleason scores (43.18+0.89 versus 52.18+0.55, p<0.001). The T2* value showed significantly greater specificity for differentiating cancerous sextants from benign PZ than ADC (93.1% versus 89.7%, p<0.001), with equal sensitivity (82.8% versus 81%, p>0.05). The T2* value exhibited significantly greater sensitivity and specificity for differentiating sextants with low- and high-grade cancer than ADC (79.6% versus 64.5% and 81.4% versus 72.9%, respectively; p<0.05). The T2* value had a significantly greater area under the receiver operating characteristic curve for differentiating sextants with low- and high-grade cancer than ADC (0.77 versus 0.71, p<0.01).

CONCLUSION

Preliminary findings suggest that the T2* relaxation time has increased diagnostic value compared with DWI in prostate PZ cancer assessment.

The Potential of High Resolution Magnetic Resonance Microscopy in the Pathologic Analysis of Resected Breast and Lymph Tissue

Pathologic evaluation of breast specimens requires a fixation and staining procedure of at least 12 hours duration, delaying diagnosis and post-operative planning. Here we introduce an MRI technique with a custom-designed radiofrequency resonator for imaging breast and lymph tissue with sufficient spatial resolution and speed to guide pathologic interpretation and offer value in clinical decision making. In this study, we demonstrate the ability to image breast and lymphatic tissue using 7.0 Tesla MRI, achieving a spatial resolution of 59 × 59 × 94 μm³ with a signal-to-noise ratio of 15–20, in an imaging time of 56 to 70 minutes. These are the first MR images to reveal characteristic pathologic features of both benign and malignant breast and lymph tissue, some of which were discernible by blinded pathologists who had no prior training in high resolution MRI interpretation.

Assessment of axillary lymph nodes in patients with breast cancer with diffusion-weighted MR imaging in combination with routine and dynamic contrast MR imaging

PURPOSE

To assess axillary lymph nodes in patients with breast cancer with diffusion-weighted MR imaging in combination with routine and dynamic contrast MR imaging.

MATERIALS AND METHODS

Prospective study was conducted on 65 enlarged axillary lymph nodes in 34 consecutive female patients (28-64 years: mean 51 years) with breast cancer. They underwent T2-weighted, dynamic contrast-enhanced and diffusion-weighted MR imaging of the breast and axilla using a single-shot echo-planar imaging with a b factor of 0500 and 1000 s/mm². Morphologic and quantitative parameters included ADC value of the axillary lymph node which was calculated and correlated with surgical findings.

RESULTS

The mean ADC value of metastatic axillary lymph nodes was 1.08 ± 0.21 × 10⁻³ mm²/s and of benign lymph nodes was 1.58 ± 0.14 × 10⁻³ mm²s. There was statistically difference in mean ADC values between metastatic and of benign axillary lymph nodes (P = 0.001). Metastatic nodes were associated with low ADC ≤ 1.3 (OR = 8.0), short axis/long axis (TS/LS) > 0.6 (OR = 7.0) and absent hilum (OR = 6.21). When ADC of 1.3 × 10⁻³ mm²/s was used as a threshold value for differentiating metastatic from benign axillary lymph nodes, the best result was obtained with an accuracy of 95.6%, sensitivity of 93%, specificity of 100%, positive predictive value of 100 %, negative predictive value of 87.5 % and area under the curve of 0.974. Multivariate model involving combined ADC value and TS/LS improved the diagnostic performance of MR imaging with AUC of 1.00.

CONCLUSION

We concluded that combination of diffusion-weighted MR imaging with morphological and dynamic MR imaging findings helps for differentiation of metastatic from benign axillary lymph nodes.

Feasibility and preliminary experience of quantitative T2* mapping at 3.0 T for detection and assessment of aggressiveness of prostate cancer

RATIONALE AND OBJECTIVES

To assess the feasibility of quantitative T2* mapping at 3.0 T for prostate cancer detection and to investigate the use of T2* values to characterize tumor aggressiveness, with whole-mount step-section pathologic analysis as the reference standard.

MATERIALS AND METHODS

Prostate multiecho T2* was performed in 55 consecutive patients with prostate cancer using a multishot fast-field echo sequence at 3.0 T magnetic resonance imaging. T2* mapping was obtained by exponentially fitting the multiecho T2* images pixel by pixel with different echo times for each slice. Generalized estimating equations were used to test the T2* value difference between normal and malignant prostate regions and the association between T2* value and tumor Gleason scores.

RESULTS

The T2* values of the cancerous prostatic regions (mean: 42.51 ± 0.65 milliseconds) were significantly lower (P < .001) than those of the normal prostatic regions (mean: 74.87 ± 0.99 milliseconds). Adopting a threshold value of 59.27 milliseconds, T2* mapping resulted in 94.8% sensitivity and 77.3% specificity in the identification of prostate cancer. A lower mean T2* value was significantly associated with a higher tumor Gleason score (mean T2* values of 53.53, 43.75, 33.66, and 22.95 milliseconds were associated with Gleason score of 3 + 3, 3 + 4, 4 + 3, and ≥8, respectively P < .05).

CONCLUSIONS

From these preliminary data, quantitative T2* mapping seems to be a potential method in the characterization of prostate cancer. T2* mapping may provide additional quantitative information that significantly correlated with prostate cancer aggressiveness.

The value of T2* in differentiating metastatic from benign axillary lymph nodes in patients with breast cancer--a preliminary in vivo study

BACKGROUND

Accurate detection and determination of axillary lymph node metastasis are crucial for the clinical management of patients with breast cancer. Noninvasive imaging methods including ultrasound (US), computed tomography (CT), or conventional magnetic resonance imaging (MRI) are not yet accurate enough. The purpose of this study was to investigate the value of in vivo T2* in differentiating metastatic from benign axillary lymph nodes in patients with breast cancer.

METHODOLOGY/PRINCIPAL FINDINGS

In this institutional review board approved study, 35 women with breast cancer underwent multi-echo T2* weighted imaging (T2*WI) of the axillary area on a 3.0 T clinical magnetic resonance (MR) imaging system. T2* values of pathologically proven benign and metastatic axillary lymph nodes were calculated and compared. Receiver operating characteristics (ROC) analysis was conducted to evaluate the diagnostic ability. The areas under the ROC curve (AUCs) and the confidence intervals (CIs) were assessed. In total, 56 metastatic and 65 benign axillary lymph nodes were identified in this study. For metastatic lymph nodes, the average T2* value (55.96±11.87 ms) was significantly longer than that of the benign lymph nodes (26.00±5.51 ms, P<0.05). The AUC of T2* in differentiating benign from metastatic lymph nodes was 0.993. The cut-off value of 37.5 milliseconds (ms) gave a sensitivity of 94.6%, a specificity of 98.5%, a positive predictive value of 98.17 and a negative predictive value 95.54.

CONCLUSIONS

In vivo T2* can differentiate benign from metastatic axillary lymph nodes in patients with breast cancer. The high sensitivity and specificity as well as the easiness suggest its high potential for use in clinical practice.

The value of 3.0Tesla diffusion-weighted MRI for pelvic nodal staging in patients with early stage cervical cancer

OBJECTIVE

The purpose of this study is to investigate the diagnostic accuracy of 3.0Tesla (3T) diffusion-weighted magnetic resonance imaging (MRI) in addition to conventional MRI for the detection of lymphadenopathy in patients with early stage cervical cancer compared to histopathological evaluation of the systematically removed pelvic lymph nodes as reference standard.

METHODS

68 fédération internationale de gynécologie obstétrique (FIGO) stage Ia2 to IIb cervical cancer patients were included. Sensitivity and specificity rates for two experienced observers were computed for the detection of lymphatic metastasis. Reproducibility of conventional MRI was tested by kappa statistics. The variables included in the analysis were: size of the long axis, short axis, ratio short to long axis and apparent diffusion coefficient (ADC).

RESULTS

Nine patients had 15 positive pelvic nodes at histopathological examination. The sensitivity and specificity of lymphatic metastasis detection by predefined conventional MRI characteristics was 33% (95% Confidence Interval (CI) 3-64) and 83% (95% CI 74-93) on patient level, and 33% (95% CI 7-60) and 97% (95% CI 95-99) on regional level respectively for observer 1. For observer 2 the sensitivity was 33% (95% CI 3-64) and the specificity 93% (95% CI 87-100) on patient level, and 25% (95% CI 1-50) and 98% (95% CI 97-100) on regional level, respectively. The kappa-value for reproducibility of metastasis detection on regional level was 0.50. The short axis diameter showed the highest diagnostic accuracy (area under the curve (AUC)=0.81 95% CI 0.70-0.91); ADC did not improve diagnostic accuracy (AUC=0.83 95% CI 0.73-0.93).

CONCLUSIONS

Diffusion-weighted MRI did not result in additional diagnostic value compared to conventional MRI.