Analysis of cervical metastatic lymphadenopathy by ultrasonography

One hundred and eight cervical lymph nodes of 37 patients were evaluated by ultrasonography. All lymph nodes were examined histologically, and among them 63 lymph nodes were metastatic nodes. If submandibular, submental, mid and inferior internal jugular lymph nodes larger than 8 mm, and superior internal jugular lymph nodes larger than 9 mm had been regarded as metastasis, high sensitivity (92%) was demonstrated. All of 31 lymph nodes with unclear or irregular margin were metastatic. Eccentric hyperechoic area, which was considered to be the hilus of the lymph node, was observed in 20 nodes. Those were non-metastatic lymph nodes. Otherwise, all of 48 lymph nodes with inhomogeneous internal echoes or with central hyperechoic area and peripheral hypoechoic zone were metastatic. The in vivo and in vitro ultrasonograms of 25 lymph nodes were compared with histopathological findings. The metastatic region was not differentiated with the remaining area of the lymph node by ultrasonography. Necrosis showed an-, hypo-, iso-, or hyperechoic. Fibrosis showed iso- or hyperechoic. Inhomogeneous internal echoes were proved to be necrosis and fibrosis, and such a lymph node was metastatic. The eccentric hyperechoic area of the non-metastatic lymph node was attributed to fatty tissue. Ultrasonography was a useful examination for evaluating cervical lymph nodes.     

The gray scale sonographic appearance of intra-abdominal mesenchymal sarcomas

Twenty-eight patients with intra-abdominal mesenchymal sarcomas were examined with gray scale ultrasonography. Masses were present in the mesentery, abdominal hollow viscera, liver, and retroperitoneal areas. Four different ultrasonic patterns were observed in the extra hepatic abdominal masses: (a) hyperechoic masses intermixed with anechoic zones; (b) hyperechoic masses with central fluid-filled zones; (c) homogeneous hyperechoic masses; and (d) homogeneous hypoechoic masses. Three of 6 patients with hepatic masses were totally anechoic alongside other more typical metastatic patterns. The presence of a large mass with sonographic signs of necrosis should strongly suggest the possibility of sarcoma. The differential diagnosis is discussed.     

Value of diffusion-weighted imaging to detect small malignant pelvic lymph nodes at 3 T

Objective

To investigate the usefulness of diffusion-weighted imaging (DWI) to discriminate between metastatic and non-metastatic small lymph nodes in pelvic carcinoma.

Materials and Methods

A total of 259 patients (180 normal, 79 metastatic) prospectively underwent DWI at 3 T. We measured the short-axis diameter and the mean apparent diffusion coefficient (ADC) value. Lymph nodes with a short-axis diameter larger than 8 mm were recorded as being suspected metastatic lymph nodes. Imaging data were correlated station by station with histopathological results.

Results

A total of 140 metastatic nodes were accurately matched with histology. On T2w, the short-axis diameter for non-metastatic and metastatic lymph nodes was 6.4 mm?±?2.5 mm and 8.3 mm?±?4.5 mm, respectively. Almost all metastatic or non-metastatic nodes had similar high signal intensity on DWI (except in 5 cases) with a homogeneous pattern. The mean ADC values (10^?3 mm³/s ± standard deviation) of involved lymph nodes, control iliac nodes and control inguinal nodes were 924?±?217, 968?±?182 and 1,036?±?181, respectively. There were no statistically significant differences in the ADC of metastatic and non-metastatic nodes.

Conclusion

Isolated measurement of mean ADC values in a suspected station does not contribute to the diagnosis of metastatic nodes, in patients with small ambiguous nodes.     

Discrimination of metastatic lymph nodes in patients with gastric carcinoma using diffusion‐weighted imaging

Purpose:

To determine the accuracy of diffusion‐weighted imaging (DWI) in discrimination of metastatic lymph nodes (LNs) in gastric carcinoma with rigorous histopathological correlation.

Materials and Methods:

With Institutional Review Board (IRB) approval, 28 patients with gastric carcinoma underwent magnetic resonance imaging (MRI) and DWI before surgery. LNs were resected at surgery and thereafter submitted for histopathological analyses. All histopathologically identified LNs (≥5 mm) that exactly matched the location and size of nodes on MRI/DWI were submitted to lesion‐by‐lesion analyses. Short‐axis diameter, border irregularity, enhanced patterns, and apparent diffusion coefficient (ADC) values of each LN were recorded. Each measurement was compared between metastatic and benign LNs, confirmed by nodal histopathology. A receiver operating characteristic (ROC) curve was generated to evaluate the capability of morphological and ADC measurements in distinguishing metastatic lymph nodes.

Results:

The median ADC value of metastatic nodes was significantly lower (1.28 × 10^?3 mm²/sec; interquartile range, 1.20–1.31) than that of benign (1.55; 1.47–1.73) nodes (P < 0.001). DWI showed greater diagnostic accuracy in determining metastatic nodes (AUC = 0.857) than the combined morphological measurements of short‐axis, border irregularity, and enhanced patterns (AUC = 0.746, P = 0.03). Adding ADC values to the combined morphologic criteria demonstrated the greatest predictive power (AUC = 0.889).

Conclusion:

DWI may provide great potential in effective discrimination of metastatic LNs in gastric carcinoma. J. Magn. Reson. Imaging 2013;37:1436–1444. © 2012 Wiley Periodicals, Inc.

     

Can ultrasound elastography distinguish metastatic from reactive lymph nodes in patients with primary head and neck cancers?

Objectives

The purpose of this study was to evaluate the diagnostic utility of real-time elastography (RTE) in differentiating between reactive and metastatic cervical lymph nodes (LN) in patients with primary head and neck cancer in comparison with the conventional B mode and power Doppler parameters.

Methods

A total of 127 lymph nodes in 78 patients with primary head and neck cancer were examined by B-mode sonography, power Doppler ultrasound and elastography. Elastographic patterns were determined on the distribution and percentage of the lymph node area with low elasticity (hard), with pattern 1 being an absent or very small hard area to pattern 5, a hard area occupying the entire lymph node. Patterns 3–5 were considered metastatic. Ultrasound guided aspiration cytology was done for 57 lymph nodes. Excision biopsy was done for 52 lymph nodes. Eighteen lymph nodes responded to conservative treatment, and were considered reactive.

Results

The majority (85.3%) of the metastatic lymph nodes had elastography pattern 3–5. This finding was observed in only 5% of the benign lymph nodes (P < 0.001). The elastography pattern had sensitivity of 85.3%, specificity of 95.5%, PPV of 97.2%, NPV of 78.1% and overall accuracy of 88.9% in differentiation between benign and malignant lymph nodes. On the other hand, for the B mode criteria, the best accuracy was given to abnormal hilum (83%). The accuracy of power Doppler ultrasound pattern was 70.8%.

Conclusions

The accuracy of sonoelastography is higher than usual B mode and power Doppler ultrasound parameters in differentiation between benign and malignant nodes. The integration of lymph node sonoelastography in the follow up of patients with known head and neck cancer may reduce the number of biopsies.     

Discrimination of axillary metastatic from nonmetastatic lymph nodes with PROPELLER diffusion-weighted MR imaging in a metastatic breast cancer model and its correlation with cellularity

Purpose:

To assess the accuracy of apparent diffusion coefficient (ADC) in the differentiation of axillary metastatic from nonmetastatic lymph nodes in rabbits with metastatic breast cancer and to determine the relationship between the ADC and the cellularity of axillary lymph nodes of two different types.

Materials and Methods:

The axillary lymph node models were created by inoculating VX2 cell suspensions in the mammary glands of 30 female rabbits. Conventional MR imaging and multi‐shot fast‐spin‐echo PROPELLER DW imaging were performed approximately 4 weeks after successful inoculation. Images of axillary lymph nodes were analyzed with regard to size and ADC. Differences in the forementioned criteria between the two types of lymph nodes were assessed with reference to histopathologic findings. Cellularity was correlated with the ADC in all selected axillary lymph nodes.

Results:

A total of 41 axillary metastatic and 29 inflammatory lymph nodes were successfully isolated. The size‐based criteria showed no significant difference between the malignant and inflammatory lymph nodes (Ps > 0.05); however, the ADC of metastatic nodes was significantly lower than that of inflammatory nodes (P < 0.001). There was a significant inverse correlation between the ADC and cellularity (r = ?0.674; P < 0.001) regardless of their different tissue types.

Conclusion:

DW imaging is a new promising functional technique for differentiating metastatic from inflammatory lymph nodes. Furthermore, cellularity has a significant influence on the ADC in both malignant and benign lymph nodes. J. Magn. Reson. Imaging 2012;36:624–631. © 2012 Wiley Periodicals, Inc.

     

Hepatocellular carcinoma: US evolution in the early stage

To study the sonographic evolution of hepatocellular carcinoma (HCC) in its early stage, 26 HCCs in 24 patients were observed regularly with real-time ultrasound for a period of 90 to 691 days. In the beginning, 21 tumors were hypoechoic, two isoechoic, and three diffusely hyperechoic. On follow-up, two of the 21 initially hypoechoic HCCs remained the same echodensity, 12 increased in internal echoes but were still hypoechoic, one became isoechoic, four changed to hyperechoic, and the remaining two shifted from hypoechoic to isoechoic and then to hyperechoic. The two initially isoechoic HCCs also gained echogenicity and became hyperechoic. By contrast, the three initially hyperechoic HCCs kept the same echo patterns. The "acquired" hyperechoic HCCs were inhomogeneous in echodensity and larger in size whereas the three originally hyperechoic HCCs were homogeneous and smaller. It is concluded that most small HCCs evolve progressively from hypoechoic to isoechoic and then to inhomogeneously hyperechoic patterns as they grow; a few HCCs have diffusely high echogenicity from the beginning and retain the same features thereafter.     

Quantitative evaluation of vascularity within cervical lymph nodes using Doppler ultrasound in patients with oral cancer: relation to lymph node size

Objectives

The aim of this study was to quantitatively evaluate the relationship between vascularity within lymph nodes and lymph node size on Doppler ultrasound images of patients with oral cancer.

Methods

A total of 310 lymph nodes (86 metastatic, 224 benign) from 63 patients with oral cancer were classified into 4 groups according to their short axis diameters: Group 1, short axis diameters of 4–5 mm; Group 2, 6–7 mm; Group 3, 8–9 mm; and Group 4, ≥10 mm. Vascular and scattering indices of lymph nodes on Doppler ultrasound images were analysed quantitatively. The vascular index was defined as the ratio of blood flow area to the whole lymph node area and the scattering index was defined as the number of isolated blood flow signal units.

Results

For metastatic lymph nodes, the vascular index was highest in Group 1 and decreased as lymph node size increased. The vascular index of benign lymph nodes did not differ significantly among the four groups. The vascular index of metastatic lymph nodes was significantly higher than that of benign lymph nodes in Group 1. For metastatic lymph nodes, the scattering index increased as lymph node size increased and was significantly higher than that of benign lymph nodes in Groups 2–4.

Conclusions

An increase in vascularity is a characteristic of Doppler ultrasound findings in small metastatic lymph nodes. As the metastatic lymph node size increases, blood flow signals become scattered, and the scattering index increases.     

Evolution of the echographic picture in primary liver tumor associated with cirrhosis

To study the sonographic (US) evolution of hepatocellular carcinoma, 53 tumors in 45 untreated patients were observed regularly with real-time US for a period of 6 to 56 months. At the beginning, 25 tumors were hypoechoic, 18 isoechoic, 4 hyperechoic, and 6 had mixed hypo/hyper echo patterns. At the follow-up, 7 initially hypoechoic tumors had changed to hyperechoic or to mixed echo patterns; 8 hypoechoic tumors had become isoechoic; 9 of the 25 initially hypoechoic neoplastic lesions had maintained the same echo density. Ten of the 15 initially isoechoic tumors had changed to mixed echo patterns, and 5 had remained unchanged. Three initially isoechoic lesions and a hypoechoic one had turned into diffuse patterns; 2 initially hyperechoic neoplastic lesions had remained unchanged; 1 had switched into hypoechoic, and 1 changed to mixed echo pattern; 4 out of 6 tumors with echo pattern had remained unchanged, 1 had become hyperechoic and 1 hypoechoic. The current study has proven various tumors less than or equal to 3 cm phi to be isoechoic, and most tumors greater than 3 cm phi to have mixed hypo/hyper echo patterns. The echogenicity of small hepatocellular carcinomas increases with the tumor growth, and remains unchanged when they do not increase in size.     

Diffusion-weighted magnetic resonance imaging in the characterization of axillary lymph nodes in patients with breast cancer

Purpose:

To assess prospectively the accuracy of diffusion‐weighted magnetic resonance imaging (DWI) in differentiating between metastatic and benign axillary lymph nodes in patients with breast cancer.

Materials and Methods:

In all, 215 patients with histologically proven breast cancer, prior to axillary dissection, underwent breast and axillary 1.5 T MRI. In 102 patients in whom at least one axillary lymph node with a short axis of 6 mm or more was found the apparent diffusion coefficient (ADC) was measured in one lymph node per patient by means of an echo planar, parallel imaging DWI sequence. Forty‐three lymph nodes were finally included which, on histological examination, either contained a metastasis larger than 5 mm or were metastasis‐free; nodes with metastases smaller than 5 mm were excluded.

Results:

From histological examination, 19/43 lymph nodes had a metastasis at least 5 mm, while in 24/43 no malignant cells were found. The ADC values of the lymph nodes with metastases (mean: 0.878 × 10^?3 mm²/s; range: 0.30 –1.20) were significantly lower (P < 0.001) than those of the benign lymph nodes (mean: 1.494; range: 0.60 –2.50). Adopting a threshold value of 1.09 × 10^?3 mm²/s DWI resulted in 94.7% sensitivity, 91.7% specificity, and 93.0% accuracy in the identification of metastasis in this series of lymph nodes.

Conclusion:

From these preliminary data DWI seems a promising method in the differential diagnosis between metastatic and benign axillary lymph nodes in patients with breast cancer. J. Magn. Reson. Imaging 2012;36:858–864. © 2012 Wiley Periodicals, Inc.

     

Hepatic tumors: US contrast enhancement with CO2 microbubbles

Enhancement of hepatic tumors on sonograms by injection of carbon dioxide microbubbles into the hepatic artery as a contrast material (enhanced ultrasonography) was performed in 43 patients with various histologically confirmed hepatic tumors. Enhanced sonograms were classified into five patterns according to the relative changes of the echo levels between the tumor and the nontumorous parenchyma of the liver as a result of enhancement: hyperechoic change, isoechoic change, hypoechoic change with hyperechoic rim (rim sign), marginal spotty hyperechoic change, and internal spotty hyperechoic change. Eighty-eight percent of hepatocellular carcinomas showed hyperechoic change, 70% of metastatic tumors exhibited hypoechoic change with the rim sign. The marginal spotty hyperechoic change and the internal spotty hyperechoic change were specific for cavernous hemangioma and fibrous granuloma, respectively. This method of enhancement is useful in assessing the nature of liver tumors and in the detection of small nodules in the liver.     

Echo pattern of lymph nodes in colorectal cancer: an in vitro study.

Surgical specimens from 75 patients with colorectal cancer were examined within 15 min of removal with a 7.5 MHz linear-array transducer. The echo pattern of 139 lymph nodes was analysed to evaluate previous criteria of malignancy and to establish other possible criteria, which could be tested in vivo. The pathologist examined each node without knowledge of the sonographic finding. Malignant nodes were larger than benign nodes. Of 21 nodes less than 5 mm in diameter, 20 were benign. Round nodes were malignant more often (45/78) than ovoid nodes (6/61). A homogeneous echo pattern was associated with malignancy in 39 of 82 nodes in contrast to 12 of 57 with a heterogeneous pattern. Thirty-one nodes were ovoid as well as heterogeneous and all of these were benign. A hyperechoic centre was found in 14 nodes of which two were malignant. The highest predictive value for malignancy (59%) was obtained by combining the discriminative properties of shape, homogeneity and echogenicity.     

Mediastinal lymph nodes: Assessment with diffusion‐weighted MR imaging

Purpose

To prospectively determine whether the diffusion‐weighted magnetic resonance imaging is useful to distinguish between malignant and benign mediastinal lymph nodes.

Materials and Methods

Thirty‐five patients (14 women, 21 men; mean age 52 years) with 91 lymph nodes in the mediastinum detected by computed tomography underwent 1.5 Tesla (T) diffusion‐weighted MR imaging before mediastinoscopy (n = 29) and mediastinotomy (n = 6). Diffusion‐weighted MR images were acquired with a b factor of 50, and 400 s/mm² using single‐shot echo‐planar sequence.

Results

Of the 35 patients, 18 had diagnosis of malignant tumor. Of the 18 patients with tumor, 8 had nonsmall cell carcinoma, and 10 had small cell carcinoma. Ninety‐one mediastinal lymph nodes were detected in the 35 untreated patients: 19 were pathologically diagnosed as metastatic lymph nodes, and 72 lymph nodes were diagnosed as nonmetastatic lymph nodes, including 50 sarcoidosis, 14 reactive lymphoid hyperplasia, and 8 necrotizing granulamatous lymphadenitis. The apparent diffusion coefficient (ADC) was significantly lower in metastatic lymph nodes (1.012 ± 0.025 × 10^?3 mm²/s; P < 0.0005) than in benign lymph nodes (1.511 ± 0.075 × 10^?3 mm²/s). On the ADC map, malignant nodes showed hyperintense (n = 2, 10.52%), hypointense (n = 14, 73.68%), and mixed intensity (n = 3; 15.78%), whereas benign nodes showed hyperintense (n = 57; 79.16%), hypointense (n = 3; 41.6%), isointense (n = 6; 8.33%), and mixed intensity (n = 6; 8.33%).

Conclusion

Diffusion‐weighted MR with ADC value and signal intensity can be useful in differentiation of malignant and benign mediastinal lymph nodes. J. Magn. Reson. Imaging 2009;30:292–297. © 2009 Wiley‐Liss, Inc.

     

Is Diffusion-Weighted MRI Useful for Differentiation of Small Non-Necrotic Cervical Lymph Nodes in Patients with Head and Neck Malignancies?

Objective

To evaluate the usefulness of measuring the apparent diffusion coefficient (ADC) in diffusion-weighted magnetic resonance imaging to distinguish benign from small, non-necrotic metastatic cervical lymph nodes in patients with head and neck cancers.

Materials and Methods

Twenty-six consecutive patients with head and neck cancer underwent diffusion-weighted imaging (b value, 0 and 800 s/mm²) preoperatively between January 2009 and December 2010. Two readers independently measured the ADC values of each cervical lymph node with a minimum-axial diameter of ≥ 5 mm but < 11 mm using manually drawn regions of interest. Necrotic lymph nodes were excluded. Mean ADC values were compared between benign and metastatic lymph nodes after correlating the pathology.

Results

A total of 116 lymph nodes (91 benign and 25 metastatic) from 25 patients were included. Metastatic lymph nodes (mean ± standard deviation [SD], 7.4 ± 1.6 mm) were larger than benign lymph nodes (mean ± SD, 6.6 ± 1.4 mm) (p = 0.018). Mean ADC values for reader 1 were 1.17 ± 0.31 × 10^-3 mm²/s for benign and 1.25 ± 0.76 × 10^-3 mm²/s for metastatic lymph nodes. Mean ADC values for reader 2 were 1.21 ± 0.46 × 10^-3 mm²/s for benign and 1.14 ± 0.34 × 10^-3 mm²/s for metastatic lymph nodes. Mean ADC values between benign and metastatic lymph nodes were not significantly different (p = 0.594 for reader 1, 0.463 for reader 2).

Conclusion

Measuring mean ADC does not allow differentiating benign from metastatic cervical lymph nodes in patients with head and neck cancer and non-necrotic, small lymph nodes.     

Differential Diagnosis of Axillary Inflammatory and Metastatic Lymph Nodes in Rabbit Models by Using Diffusion-Weighted Imaging: Compared with Conventional Magnetic Resonance Imaging

Objective

This experiment aims to determine the diagnostic value of diffusion-weighted imaging (DWI) in the differentiation of axillary inflammatory lymph nodes from metastatic lymph nodes in rabbit models in comparison with conventional magnetic resonance imaging (MRI).

Materials and Methods

Conventional MRI and DWI were performed at 4 weeks after successful inoculation into the forty female New Zealand white rabbits'' mammary glands. The size-based and signal-intensity-based criteria and the relative apparent diffusion coefficient (rADC) value were compared between the axillary inflammatory lymph nodes and metastatic lymph nodes, with histopathological findings as the reference standard. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic performance of the aforementioned criteria and rADC value in differentiating the axillary inflammatory lymph nodes from metastatic lymph nodes.

Results

Thirty-two axillary inflammatory lymph nodes and 46 metastatic ones were successfully isolated and taken into pathological analysis. The differences of the aforementioned criteria between the two groups were not statistically significant (p > 0.05). However, the rADC value of the inflammatory lymph nodes (0.9 ± 0.14) was higher than that of metastatic ones (0.7 ± 0.18), with significant difference (p = 0.016). When the rADC value was chosen as 0.80, the area under the ROC curve is greater than all other criteria, and the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for differentiating two groups were 86.2%, 79.3%, 81.2%, 84.2%, and 85.6%, respectively.

Conclusion

Diffusion-weighted imaging is a promising new technique for differentiating axillary inflammatory lymph nodes from metastatic lymph nodes. Compared with routine magnetic resonance sequences, DWI could provide more useful physiological and functional information for diagnosis.     

Diagnostic accuracy of apparent diffusion coefficient value in differentiating metastatic form benign axillary lymph nodes in cancer breast

Purpose

To detect axillary lymph node metastasis based on diffusion Weighted MR and apparent diffusion coefficient (ADC) in the known breast cancer cases.

Patient and methods

Forty-four patients were included in this study for preoperative MRI staging of the breast cancer and axillary lymph node assessment. The lymph node criteria (long/short-axis ratio, T2WI, DWI and ADC value) were included in the analysis. Images were obtained with diffusion sensitizing gradients of 0 and 750 mm²/s. The ADC was calculated.

Results

Thirty-two patients had metastatic axillary lymph nodes and 12 cases had no malignant LN involvement. There was no significant difference between both in S/L ratio, T2WISI (p < 0.140 & p = 0.079, respectively), while statistically significant difference between benign and malignant lymph nodes in both DWI and ADC mean values (p < 0.0001 & p < 0.007, respectively). The optimal ADC cut off value was ?.8 × 10⁻³ mm²/s for differentiation between benign and malignant lymph nodes with accuracy 96.7%, sensitivity 100%, specificity 87%, PPV 95.4% and NPV 100%.

Conclusion

Compared with lymph node size or routine magnetic resonance sequences, DWI and ADC are promising techniques for differentiating metastatic and non metastatic axillary lymph nodes in known breast cancer patients.     

Effectiveness of the STIR turbo spin–echo sequence MR imaging in evaluation of lymphadenopathy in esophageal cancer

Purpose

We have investigated the utility of the STIR TSE sequence in the differentiation of benign from malignant mediastinal lymph nodes in patients with esophageal cancer.

Patients and methods

This study included 35 consecutive patients who were diagnosed as esophageal cancer and were undergone surgery. STIR TSE sequences were obtained as the ECG trigger. The signal intensity of the benign and malign lymph nodes, normal esophagus, and pathologic esophagus can be calculated on STIR sequence.

Results

Pathologically, the number of total lymph nodes in 35 operated cases was 482. Approximately 152 lymph nodes were detected with MR imaging. Of these, 28 were thought to be malignant, and 124 were thought to be benign, although 32 were malignant and 120 were benign according pathological results. The ratio of benign lymph node intensity value to normal esophagus intensity value was 0.73 ± 0.3. The ratio of malignant lymph node intensity value to normal esophagus intensity value ratio was 2.03 ± 0.4. According to these results, the sensitivity of MR was 81.3%, the specificity was 98.3%.

Conclusion

We think that if motionless images can be obtained with MRI, we may be able to differentiate benign lymph nodes from malignant ones.     

Assessment of Lymph Node Metastases by Contrast-Enhanced MR Imaging in a Head and Neck Cancer Model

Objective

We wanted to investigate the accuracy of contrast-enhanced MR imaging for the detection of lymph node metastases in a head and neck cancer rabbit model.

Materials and Methods

The metastatic lymph node model we used was created by inoculating VX2 tumors into the auricles of six New Zealand White rabbits. T1-weighted MR images were obtained before and after injecting gadopentetate dimeglumine at three weeks after tumor cell inoculation. The sizes, signal intensity ratios (i.e., the postcontrast signal intensities of the affected nodes relative to the adjacent muscle) and the enhancement patterns of 36 regional lymph nodes (parotid and caudal mandibular nodes) were evaluated on MR images and then compared with the histopathologic findings.

Results

No statistical difference was found between the sizes of 12 metastatic (10.5±3.2 mm) and 24 hyperplastic (8.0±3.6 mm) lymph nodes (p > 0.05). On the contrast-enhanced T1-weighted MR images, nine metastatic and four hyperplastic lymph nodes had peripheral high and central low signal intensity, whereas three metastatic and 20 hyperplastic lymph nodes had homogeneous high signal intensity. Using a signal intensity ratio less than one as a diagnostic criterion for a metastatic lymph node, the sensitivity, specificity and positive and negative predictive values of the enhanced MR images were 75% (9/12), 83% (20/24), 69% (9/13) and 87% (20/23), respectively, with areas under receiver-operating-characteristic curve values of 0.81.

Conclusion

This experimental study confirms that metastatic and hyperplastic lymph nodes can be differentiated using MR images on the basis of the contrast uptake patterns, but that they cannot be differentiated using any particular size criteria.     

Diffusion-weighted MR imaging in primary rectal cancer staging demonstrates but does not characterise lymph nodes

Objectives

To evaluate the performance of diffusion-weighted MRI (DWI) for the detection of lymph nodes and for differentiating between benign and metastatic nodes during primary rectal cancer staging.

Methods

Twenty-one patients underwent 1.5-T MRI followed by surgery (± preoperative 5?×?5 Gy). Imaging consisted of T2-weighted MRI, DWI (b0, 500, 1000), and 3DT1-weighted MRI with 1-mm isotropic voxels. The latter was used for accurate detection and per lesion histological validation of nodes. Two independent readers analysed the signal intensity on DWI and measured the mean apparent diffusion coefficient (ADC) for each node (ADC_node) and the ADC of each node relative to the mean tumour ADC (ADC_rel).

Results

DWI detected 6 % more nodes than T2W-MRI. The signal on DWI was not accurate for the differentiation of metastatic nodes (AUC 0.45–0.50). Interobserver reproducibility for the nodal ADC measurements was excellent (ICC 0.93). Mean ADC_node was higher for benign than for malignant nodes (1.15?±?0.24 vs. 1.04?±?0.22 *10^-3 mm²/s), though not statistically significant (P?=?0.10). Area under the ROC curve/sensitivity/specificity for the assessment of metastatic nodes were 0.64/67 %/60 % for ADC_node and 0.67/75 %/61 % for ADC_rel.

Conclusions

DWI can facilitate lymph node detection, but alone it is not reliable for differentiating between benign and malignant lymph nodes.

Key Points

? Diffusion-weighted (DW) magnetic resonance imaging (MRI) offers new information in rectal cancer. ? DW MRI demonstrates more lymph nodes than standard T2-weighted MRI. ? Visual DWI assessment does not discriminate between benign and metastatic nodes. ? Apparent diffusion coefficients do not discriminate between benign and metastatic nodes.     

Ratio of Mediastinal Lymph Node SUV to Primary Tumor SUV in <Superscript>18</Superscript>F-FDG PET/CT for Nodal Staging in Non-Small-Cell Lung Cancer

Purpose

Following determination of the maximum standardized uptake values (SUVmax) of the mediastinal lymph nodes (SUV-LN) and of the primary tumor (SUV-T) on ¹⁸F-FDG PET/CT in patients with non-small-cell lung cancer (NSCLC), the aim of the study was to determine the value of the SUV-LN/SUV-T ratio in lymph node staging in comparison with that of SUV-LN.

Methods

We retrospectively reviewed a total of 289 mediastinal lymph node stations from 98 patients with NSCLC who were examined preoperatively for staging and subsequently underwent pathologic studies of the mediastinal lymph nodes. We determined SUV-LN and SUV-R for each lymph node station on ¹⁸F-FDG PET/CT and then classified each station into one of three groups based on SUV-T (low, medium and high SUV-T groups). Diagnostic performance was assessed based on receiver operating characteristic (ROC) curve analysis, and the optimal cut-off values that would best discriminate metastatic from benign lymph nodes were determined for each method.

Results

The average of SUV-R of malignant lymph nodes was significantly higher than that of benign lymph nodes (0.79?±?0.45 vs. 0.36?±?0.23, P?<?0.0001). In the ROC curve analysis, the area under the curve (AUC) of SUV-R was significantly higher than that of SUV-LN in the low SUV-T group (0.885 vs. 0.810, P?=?0.019). There were no significant differences between the AUCs of SUV-LN and of SUV-R in the medium and high SUV-T groups. The optimal cut-off value for SUV-R in the low SUV-T group was 0.71 (sensitivity 87.5 %, specificity 85.9 %).

Conclusions

The SUV-R performed well in distinguishing between metastatic and benign lymph nodes. In particular, SUV-R was found to have a better diagnostic performance than SUV-LN in the low SUV-T group.