Added value of diffusion-weighted MR imaging to T2-weighted and dynamic contrast-enhanced MR imaging in T staging of gastric cancer

Value of orthogonal axial MR images in preoperative T staging of gastric cancer

PURPOSE

To assess the value of orthogonal axial images (OAI) of MRI in gastric cancer T staging.

METHODS

This retrospective study enrolled 133 patients (median age, 63 [range, 24-85] years) with gastric adenocarcinoma who underwent both CT and MRI followed by surgery. MRI lacking or incorporating OAI and CT images were evaluated, respectively. Diagnostic performance (accuracy, sensitivity, and specificity) for each T stage, overall diagnostic accuracy and rates of over- and understaging were quantified employing pathological T stage as a reference standard. The McNemar's test was performed to compare the overall accuracy.

RESULTS

Among patients with pT1-pT4 disease, MRI with OAI (accuracy: 88.7-94.7%, sensitivity: 66.7-93.0%, specificity: 91.5-100.0%) exhibited superior diagnostic performance compared to MRI without OAI (accuracy: 81.2-88.7%, sensitivity: 46.2-83.1%, specificity: 85.5-99.1%) and CT (accuracy: 88.0-92.5%, sensitivity: 53.3-90.1%, specificity: 88.7-98.1%). The overall accuracy of MRI with OAI was significantly higher (83.5%) than that of MRI without OAI (67.7%) (p < .001). However, there was no significant difference in the overall accuracy of MRI with OAI and CT (78.9%) (p = .35). The over- and understaging rates of MRI with OAI (12.0, 4.5%) were lower than those of MRI without OAI (21.8, 10.5%) and CT (12.8, 8.3%).

CONCLUSION

OAI play a pivotal role in the T staging of gastric cancer. MRI incorporating OAI demonstrated commendable performance for gastric cancer T-staging, with a slight tendency toward its superiority over CT.

Cross-sectional imaging of gastric cancer: pearls, pitfalls and lessons learned from multidisciplinary conference

Gastric cancer is rising in prevalence associated with high mortality, primarily due to late-stage detection, underscoring the imperative for early and precise diagnosis. Etiology involves an interplay of genetic susceptibilities and environmental factors with a prominent role of Helicobacter pylori infection. Due to its often-delayed symptom presentation, prompt and accurate diagnosis is necessary. A multimodal imaging approach, including endoscopic ultrasound (EUS), multi-detector computed tomography (MDCT), and magnetic resonance imaging (MRI) is critical for accurate staging. Each modality contributes unique advantages and limitations, highlighting the importance of integrating diagnostic strategy. Moreover, multidisciplinary conferences offer a vital collaborative platform, bringing together specialists from diverse fields for treatment planning. This synergistic approach not only enhances diagnostic precision but also improves patient outcome. This review highlights the critical role of imaging in diagnosis, staging, and management and advocates for interdisciplinary collaboration in early detection and comprehensive management of gastric cancer, aiming to reduce mortality.

Imaging in Gastric Cancer: Current Practice and Future Perspectives

Gastric cancer represents one of the most common oncological causes of death worldwide. In order to treat patients in the best possible way, the staging of gastric cancer should be accurate. In this regard, endoscopy ultrasound (EUS) has been considered the reference standard for tumor (T) and nodal (N) statuses in recent decades. However, thanks to technological improvements, computed tomography (CT) has gained an important role, not only in the assessment of distant metastases (M status) but also in T and N staging. In addition, magnetic resonance imaging (MRI) can contribute to the detection and staging of primary gastric tumors thanks to its excellent soft tissue contrast and multiple imaging sequences without radiation-related risks. In addition, MRI can help with the detection of liver metastases, especially small lesions. Finally, positron emission tomography (PET) is still considered a useful diagnostic tool for the staging of gastric cancer patients, with a focus on nodal metastases and peritoneal carcinomatosis. In addition, it may play a role in the treatment of gastric cancer in the coming years thanks to the introduction of new labeling peptides. This review aims to summarize the most common advantages and pitfalls of EUS, CT, MRI and PET in the TNM staging of gastric cancer patients.

Differentiating T1a-T1b from T2 in gastric cancer lesions with three different measurement approaches based on contrast-enhanced T1W imaging at 3.0 T

Background

To explore the diagnostic value of three different measurement approaches in differentiating T1a–T1b from T2 gastric cancer (GC) lesions.

Methods

A total of 95 consecutive patients with T1a–T2 stage of GC who performed preoperative MRI were retrospectively enrolled between January 2017 and November 2020. The parameters MRI T stage (subjective evaluation), thickness, maximum area and volume of the lesions were evaluated by two radiologists. Specific indicators including AUC, optimal cutoff, sensitivity, specificity, accuracy, positive likelihood ratio (PLR), negative likelihood ratio (NLR), positive predictive value (PPV) and negative predictive value (NPV) of MRI T stage, thickness, maximum area and volume for differentiating T1a–T1b from T2 stage lesions were calculated. The ROC curves were compared by the Delong test. Decision curve analysis (DCA) was used to evaluate the clinical benefit.

Results

The ROC curves for thickness (AUC = 0.926), maximum area (AUC = 0.902) and volume (AUC = 0.897) were all significantly better than those of the MRI T stage (AUC = 0.807) in differentiating T1a–T1b from T2 lesions, with p values of 0.004, 0.034 and 0.041, respectively. The values corresponding to the thickness (including AUC, sensitivity, specificity, accuracy, PPV, NPV, PLR and NLR) were all higher than those corresponding to the MRI T stage, maximum area and volume. The DCA curves indicated that the parameter thickness could provide the highest clinical benefit if the threshold probability was above 35%.

Conclusions

Thickness may provide an efficient approach to rapidly distinguish T1a–T1b from T2 stage GC lesions.

Quantitative study of preoperative staging of gastric cancer using intravoxel incoherent motion diffusion-weighted imaging as a potential clinical index

PURPOSE

To determine the utility of intravoxel incoherent motion (IVIM) diffusion-weighted imaging in quantitative analysis of preoperative tumor (T) and node (N) stages of gastric cancer, and to quantify the diagnostic threshold of IVIM parameters for serosal invasion and lymphatic metastasis.

MATERIALS AND METHODS

From October 2016 to February 2020, 98 patients with gastric cancer who were receiving treatment in Zhongshan Hospital, China, were subject to an IVIM sequence imaging analysis. The IVIM sequence data were imported into software for post-processing of tumor regions of interest, and the IVIM parameters (the microvascular volume fraction (f), the molecular diffusion coefficient (D) and perfusion-related incoherent microcirculation (D*) were calculated. The variation of these IVIM parameters with different tumor-node metastasis (TNM) stages were analyzed by one-way analysis of variance. The IVIM parameters of serosal invasion and lymphatic metastasis were examined by receiver operating characteristic curve analysis and t-tests.

RESULTS

A total of 98 gastric cancer patients (65 males and 33 females) with an average age of 61.9 years were enrolled in this study. There were 14 patients in stage T1, 14 in stage T2, 10 in stage T3 and 60 in stage T4_a+b. There were 37 patients in stage N0, 19 in stage N1, 18 in stage N2 and 24 in stage N3. Statistically significant associations were found between the D values and T stages of gastric cancer. The D values of stage T4 cancers were significantly different from those of stage T2, T3 and T4 cancers. The D value decreased with increasing T stage. The mean D values of stages were 1.432 × 10^-3 mm²/s (T1), 1.225 × 10^-3 mm²/s (T2), 1.154 × 10^-3 mm²/s (T3) and 0.9468 × 10^-3 mm²/s (T4). The extent of the invasion of serosa was found to be significantly correlated with D value, with the diagnostic threshold for D being 1.107 × 10^-3 mm²/s. In addition, different pathological N stages of gastric cancer lesions showed statistically significantly variations in f values, but no correlation was found with different N stages. Finally, the extent of lymphatic metastasis was found to be correlated with D values, with the diagnostic threshold being 1.1739 × 10^-3 mm²/s. There was no statistically significant correlation between the IVIM MRI parameters and tumor size. The grade of tumor was found to be significantly correlated with D* value, with the diagnostic threshold for D* being 1.516 × 10^-2 mm²/s. There was no statistically significant correlation between the ADC value and tumor size. There was a significant difference in the ADC values among different T and N stage cancers. ADC value had statistically significant to distinguish gastric cancer with or without serosal invasion, its detection efficiency was not as high as that of D value, with an AUC of 0.628 and 0.830, respectively. The ADC value was not statistically significant in distinguishing gastric cancer with or without lymphatic metastasis (P ≥ 0.05). The ADC value had not statistically significant in distinguishing gastric cancer between low and medium-high grade (P ≥ 0.05).

CONCLUSION

We found that significant differences existed between whole-volume IVIM parameters of different T or N stages in gastric cancers, and were able to quantify different T or N stages of gastric cancer by the values of these parameters. The results of this quantitative study provide new tools for evaluating the prognosis of gastric cancer and will be valuable for the development of an new imaging method for determining the morphological stages of gastric cancer.

Esophagus and Stomach: Is There a Role for MR Imaging?

MR imaging has been increasingly used in the diagnostic work-up of benign and malignant conditions of the gastroesophageal tract. The use of an adequate MR imaging protocol is crucial, although standardization of imaging studies is still far from being implemented. Research on MR imaging-based biomarkers show promising results in assessing tumor aggressiveness and prognosis, and in the evaluation of response to treatment, both in esophageal and gastric cancers.

The role of MRI in the diagnosis and treatment of gastric cancer

Gastric cancer is the fifth most common malignancies and the third leading cause of cancer-related death worldwide, with more than 40% of new cases occurring in China. With the advancement of treatment methods, the application of adjuvant therapy and targeted drugs, the prognosis of patients with gastric cancer has been significantly improved. In recent years, more and more studies have reported that magnetic resonance imaging (MRI) showed great value in the clinical application among patients with gastric cancer, including preoperative staging, treatment response evaluation, predicting prognosis and histopathological features, treatment guidance, and molecular imaging. The remarkable research progress of MRI in gastric cancer will provide new evaluation and treatment approaches for clinical diagnosis and treatment. This article aims to review the current status of the application and research progress of MRI in patients with gastric cancer.

Diagnostic performance in T staging for patients with esophagogastric junction cancer using high-resolution MRI: a comparison with conventional MRI at 3 tesla

BACKGROUND

To investigate and compare the diagnostic performance in T staging for patients with esophagogastric junction cancer using high-resolution magnetic resonance imaging (HR MRI), as compared with conventional MRI at 3 Tesla.

METHODS

A total of 118 patients with pathologically confirmed esophagogastric junction cancer were included and underwent multiparameter HR MRI (Cohort 1, 62 patients) or conventional MRI (Cohort 2, 56 patients). T2-weighted, T1-weighted, diffusion-weighted and contrast-enhanced T1-weighted images of each patient were evaluated by two radiologists who determined the preoperative T staging by consensus. Using pathologic staging as the gold standard, the consistency between HR MRI and pathology and between conventional MRI and pathology in T staging was calculated and compared. The overall accuracy, overstatement and understatement of HR MRI and conventional MRI in T staging of patients with esophagogastric junction cancer were computed and compared. Moreover, the diagnostic performance of HR MRI and conventional MRI in T staging (≤ T1 and ≥ T4) of patients with esophagogastric junction cancer were evaluated.

RESULTS

There were no significant differences in age (p = 0.465) and sex (p = 0.175) between Cohorts 1 and 2. Excellent agreement was observed in the T staging of patients with esophagogastric junction cancer between pathology and HR MRI (kappa = 0.813), while moderate agreement was observed between pathology and conventional MRI (kappa = 0.486). Significant differences were observed in overall accuracy (88.7% vs 64.3%, p = 0.002) and understatement (1.6% vs 26.8%, p < 0.001) but not for overstatement (9.7% vs 8.9%, p = 0.889) in T staging between HR MRI and conventional MRI techniques. For differentiating the T stages of ≤ T1 from ≥ T2 and the T stages of ≤ T3 from ≥ T4, no significant differences were observed between the imaging techniques.

CONCLUSIONS

HR MRI has good diagnostic performance and may serve as an alternative technique in the T staging of patients with esophagogastric junction cancer in clinical practice.

Imaging strategies in the management of gastric cancer: current role and future potential of MRI

Accurate preoperative staging of gastric cancer and the assessment of tumor response to neoadjuvant treatment is of importance for treatment and prognosis. Current imaging techniques, mainly endoscopic ultrasonography (EUS), computed tomography (CT) and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET), have their limitations. Historically, the role of magnetic resonance imaging (MRI) in gastric cancer has been limited, but with the continuous technical improvements, MRI has become a more potent imaging technique for gastrointestinal malignancies. The accuracy of MRI for T- and N-staging of gastric cancer is similar to EUS and CT, making MRI a suitable alternative to other imaging strategies. There is limited evidence on the performance of MRI for M-staging of gastric cancer specifically, but MRI is widely used for diagnosing liver metastases and shows potential for diagnosing peritoneal seeding. Recent pilot studies showed that treatment response assessment as well as detection of lymph node metastases and systemic disease might benefit from functional MRI (e.g. diffusion weighted imaging and dynamic contrast enhancement). Regarding treatment guidance, additional value of MRI might be expected from its role in better defining clinical target volumes and setup verification with MR-guided radiation treatment.

Magnetic Semiconductor Gd-Doping CuS Nanoparticles as Activatable Nanoprobes for Bimodal Imaging and Targeted Photothermal Therapy of Gastric Tumors

Targeted delivery of enzyme-activatable probes into cancer cells to facilitate accurate imaging and on-demand photothermal therapy (PTT) of cancers with high spatiotemporal precision promises to advance cancer diagnosis and therapy. Here, we report a tumor-targeted and matrix metalloprotease-2 (MMP-2)-activatable nanoprobe (T-MAN) formed by covalent modification of Gd-doping CuS micellar nanoparticles with cRGD and an MMP-2-cleavable fluorescent substrate. T-MAN displays a high r₁ relaxivity (∼60.0 mM^-1 s^-1 per Gd³⁺ at 1 T) and a large near-infrared (NIR) fluorescence turn-on ratio (∼185-fold) in response to MMP-2, allowing high-spatial-resolution magnetic resonance imaging (MRI) and low-background fluorescence imaging of gastric tumors as well as lymph node (LN) metastasis in living mice. Moreover, T-MAN has a high photothermal conversion efficiency (PCE, ∼70.1%) under 808 nm laser irradiation, endowing it with the ability to efficiently generate heat to kill tumor cells. We demonstrate that T-MAN can accumulate preferentially in gastric tumors (∼23.4% ID%/g at 12 h) after intravenous injection into mice, creating opportunities for fluorescence/MR bimodal imaging-guided PTT of subcutaneous and metastatic gastric tumors. For the first time, accurate detection and laser irradiation-initiated photothermal ablation of orthotopic gastric tumors in intraoperative mice was also achieved. This study highlights the versatility of using a combination of dual biomarker recognition (i.e., α_vβ₃ and MMP-2) and dual modality imaging (i.e., MRI and NIR fluorescence) to design tumor-targeting and activatable nanoprobes with improved selectivity for cancer theranostics in vivo.

Gastric cancer and imaging biomarkers: Part 1 - a critical review of DW-MRI and CE-MDCT findings

Abstract

The current standard of care for gastric cancer imaging includes heterogeneity in image acquisition techniques and qualitative image interpretation. In addition to qualitative assessment, several imaging techniques, including diffusion-weighted magnetic resonance imaging (DW-MRI), contrast-enhanced multidetector computed tomography (CE-MDCT), dynamic-contrast enhanced MRI and 18F-fluorodeoxyglucose positron emission tomography, can allow quantitative analysis. However, so far there is no consensus regarding the application of functional imaging in the management of gastric cancer. The aim of this article is to specifically review two promising biomarkers for gastric cancer with reasonable spatial resolution: the apparent diffusion coefficient (ADC) from DW-MRI and textural features from CE-MDCT. We searched MEDLINE/ PubMed for manuscripts published from inception to 6 February 2018. Initially, we searched for (gastric cancer OR gastric tumour) AND diffusion weighted magnetic resonance imaging. Then, we searched for (gastric cancer OR gastric tumour) AND texture analysis AND computed tomography. We collated the results from the studies related to this query. There is evidence that: (1) the ADC is a promising biomarker for the evaluation of the aggressiveness (T and N stage), treatment response and prognosis of gastric cancer; (2) textural features are related to the degree of differentiation, Lauren classification, treatment response and prognosis of gastric cancer. We conclude that these imaging biomarkers hold promise as effective additional tools in the diagnostic pathway of gastric cancer and may facilitate the multidisciplinary work between the radiologist and clinician, and across different institutions, to provide a greater biological understanding of gastric cancer.

Key Points

• Quantitative imaging is the extraction of quantifiable features from medical images for the assessment of normal or pathological conditions and represents a promising area for gastric cancer.

• Quantitative analysis from CE-MDCT and DW-MRI allows the extrapolation of multiple imaging biomarkers.

• ADC from DW-MRI and CE- MDCT-based texture features are non-invasive, quantitative imaging biomarkers that hold promise in the evaluation of the aggressiveness, treatment response and prognosis of gastric cancer.

Prognostic significance of low miR-144 expression in gastric cancer

BACKGROUND

An overwhelming amount of evidence has emerged suggesting that dysregulated microRNAs (miRNAs) play crucial roles in tumorigenesis.

OBJECTIVE

The study was to analyze tissue/serum miR-144 expression in gastric cancer and then evaluate their potential to predict the prognosis of gastric cancer.

METHODS

We examined miR-144 levels in tissues and peripheral blood samples from 96 gastric cancer patients using real-time PCR. Then the association between tissue/serum miR-144 levels and clinicopathological parameters was determined.

RESULTS

The expression levels of miR-144 were significantly down-regulated in the cancerous tissue and serum samples from gastric cancer patients. Serum miR-144 was able to differentiate the gastric cancer patients from healthy controls with high accuracy. In addition, tissue and serum miR-144 levels were both associated with clinical stage and lymph node metastasis. Moreover, patients with lower tissue or serum miR-144 suffered worse 5 year overall survival and disease free survival.

CONCLUSIONS

Taken together, our data support the potential clinical value of tissue and serum miR-144 as prognostic biomarkers in gastric cancer.

Role of intravoxel incoherent motion MR imaging in preoperative assessing HER2 status of gastric cancers

Purpose

To explore the role of intravoxel incoherent motion (IVIM) magnetic resonance (MR) imaging in evaluating human epidermal growth factor receptor 2 (HER2) status of gastric cancers preoperatively.

Results

The apparent diffusion coefficient (ADC) and pure diffusion coefficient (D) values correlated positively with HER2 scores of gastric cancers significantly (r = 0.276, P = 0.048; r = 0.481, P < 0.001, respectively). The ADC and D values of HER2 positive gastric cancers were significantly higher than those of HER2 negative tumors (P = 0.033, 0.007, respectively). With a cut-off value of 1.321 and 1.123 × 10⁻³ mm²/sec, the ADC and D values could distinguish HER2 positive gastric cancers from HER2 negative ones with an area under the curve of 0.733 and 0.762, respectively (P = 0.023, 0.011, respectively).

Materials and methods

Fifty-three patients with gastric cancers underwent IVIM MR imaging preoperatively. The values of ADC, D, pseudo diffusion coefficient (D*) and perfusion related fraction (f) of the lesions were obtained. Partial correlation test including tumor volume was performed to analyze correlations between IVIM values and HER2 scores excluding the impact of tumor size. IVIM parameters of gastric cancers with different HER2 status were compared using independent samples t test. Diagnostic performance of IVIM parameters in distinguishing HER2 positive gastric cancers from negative ones was tested with receiver operating characteristic analysis.

Conclusions

We confirmed the feasibility of IVIM MR imaging in preoperative assessment of HER2 status of gastric cancers, which might make up the shortfall of biopsy and facilitate personalized treatment for patients with gastric cancers.

Predicting the nodal status in gastric cancers: The role of apparent diffusion coefficient histogram characteristic analysis

PURPOSE

To explore the application of histogram analysis in preoperative T and N staging of gastric cancers, with a focus on characteristic parameters of apparent diffusion coefficient (ADC) maps.

MATERIALS AND METHODS

Eighty-seven patients with gastric cancers underwent diffusion weighted magnetic resonance imaging (b=0, 1000s/mm²), which generated ADC maps. Whole-volume histogram analysis was performed on ADC maps and 7 characteristic parameters were obtained. All those patients underwent surgery and postoperative pathologic T and N stages were determined.

RESULTS

Four parameters, including skew, kurtosis, s-sD_av and sample number, showed significant differences among gastric cancers at different T and N stages. Most parameters correlated with T and N stages significantly and worked in differentiating gastric cancers at different T or N stages. Especially skew yielded a sensitivity of 0.758, a specificity of 0.810, and an area under the curve (AUC) of 0.802 for differentiating gastric cancers with and without lymph node metastasis (P<0.001). All the parameters, except AUC_low, showed good or excellent inter-observer agreement with intra-class correlation coefficients ranging from 0.710 to 0.991.

CONCLUSION

Characteristic parameters derived from whole-volume ADC histogram analysis could help assessing preoperative T and N stages of gastric cancers.

Whole-volume apparent diffusion coefficient-based entropy parameters for assessment of gastric cancer aggressiveness

PURPOSE

To explore the role of whole-volume apparent diffusion coefficient (ADC)-based entropy parameters in the preoperative assessment of gastric cancer's aggressiveness.

MATERIALS AND METHODS

In all, 64 patients with gastric cancers who underwent 3.0T magnetic resonance imaging (MRI) were retrospectively included. Regions of interest were drawn manually using in-house software, around gastric cancer lesions on each slice of the diffusion-weighted images and ADC maps. Entropy-related parameters based on ADC maps were calculated automatically: (1) first-order entropy; (2-5) second-order entropies, including entropy(H)₀ , entropy(H)₄₅ , entropy(H)₉₀ , and entropy(H)₁₃₅ ; (6) entropy(H)_mean ; and (7) entropy(H)_range . Correlations between entropy-related parameters and pathological characteristics were analyzed with the Spearman correlation test. The parameters were compared among different pathological characteristics with independent-samples Kruskal-Wallis or Mann-Whitney U-test. Additionally, diagnostic performances of parameters in differentiating different pathological characteristics were analyzed by receiver operating characteristic (ROC) curve analysis.

RESULTS

All the entropy-related parameters significantly correlated with T, N, and overall stages, especially the first-order entropy (r = 0.588, 0.585, and 0.677, respectively, all P < 0.05). All the entropy-related parameters showed significant differences in gastric cancers at different T, N, and overall stages, as well as at different status of vascular invasion (P < 0.001-0.027). And four parameters, including entropy, entropy(H)₀ , entropy(H)₄₅ , and entropy(H)₉₀ , showed significant differences between gastric cancers with and without perineural invasion (P 0.006-0.040).

CONCLUSION

Entropy-related parameters derived from whole-volume ADC texture analysis could help assess the aggressiveness of gastric cancers via analyzing intratumoral heterogeneity quantitatively, especially the first-order entropy.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:168-175.

Apparent diffusion coefficient by diffusion-weighted magnetic resonance imaging as a sole biomarker for staging and prognosis of gastric cancer

Objective

To investigate the role of apparent diffusion coefficient (ADC) from diffusion-weighted magnetic resonance imaging (DW-MRI) when applied to the 7th TNM classification in the staging and prognosis of gastric cancer (GC).

Methods

Between October 2009 and May 2014, a total of 89 patients with non-metastatic, biopsy proven GC underwent 1.5T DW-MRI, and then treated with radical surgery. Tumor ADC was measured retrospectively and compared with final histology following the 7th TNM staging (local invasion, nodal involvement and according to the different groups — stage I, II and III). Kaplan-Meier curves were also generated. The follow-up period is updated to May 2016.

Results

Median follow-up period was 33 months and 45/89 (51%) deaths from GC were observed. ADC was significantly different both for local invasion and nodal involvement (P<0.001). Considering final histology as the reference standard, a preoperative ADC cut-off of 1.80×10^–3 mm²/s could distinguish between stages I and II and an ADC value of ≤1.36×10^–3 mm²/s was associated with stage III (P<0.001). Kaplan-Meier curves demonstrated that the survival rates for the three prognostic groups were significantly different according to final histology and ADC cut-offs (P<0.001).

Conclusions

ADC is different according to local invasion, nodal involvement and the 7th TNM stage groups for GC, representing a potential, additional prognostic biomarker. The addition of DW-MRI could aid in the staging and risk stratification of GC.

Diffusion-weighted whole-body imaging with background body signal suppression/T2 image fusion and positron emission tomography/computed tomography of upper gastrointestinal cancers

PURPOSE

Diffusion-weighted whole-body imaging with background body signal suppression/T2 image fusion (DWIBS/T2) strongly contrasts cancerous tissue against background healthy tissues. Positron emission tomography/computed tomography (PET/CT) applies the uptake of 18-fluorodeoxyglucose in the diagnosis of cancer. Our aim was to compare DWIBS/T2 and PET/CT in patients with upper gastrointestinal cancers.

METHODS

Patient records, including imaging results from July 2012 to March 2015, were analyzed retrospectively. Four men (age, 72.5 ± 5.3 years) and ten women (age, 71.6 ± 4.0 years) were enrolled in this study. The numbers of patients with esophageal cancer, gastric cancer, gastrointestinal stromal tumor, and duodenal cancer were one, eight, three, and two, respectively.

RESULTS

Six out of eight patients with gastric cancer had positive results on both DWIBS/T2 and PET/CT. The diameter and depth of invasion of gastric cancer was larger in patients with positive DWIBS/T2 and PET/CT findings than those with negative findings. These results suggested that patients with gastric cancer with larger pixel numbers might tend to show positive results with DWIBS/T2.

CONCLUSIONS

DWIBS/T2 and PET/CT have similar sensitivity for the diagnosis of upper gastrointestinal cancer. The diameter and depth of invasion affected the detectability of gastric cancer.

Assessment of histological differentiation in gastric cancers using whole-volume histogram analysis of apparent diffusion coefficient maps

PURPOSE

To investigate the efficacy of histogram analysis of the entire tumor volume in apparent diffusion coefficient (ADC) maps for differentiating between histological grades in gastric cancer.

MATERIALS AND METHODS

Seventy-eight patients with gastric cancer were enrolled in a retrospective 3.0T magnetic resonance imaging (MRI) study. ADC maps were obtained at two different b values (0 and 1000 sec/mm² ) for each patient. Tumors were delineated on each slice of the ADC maps, and a histogram for the entire tumor volume was subsequently generated. A series of histogram parameters (eg, skew and kurtosis) were calculated and correlated with the histological grade of the surgical specimen. The diagnostic performance of each parameter for distinguishing poorly from moderately well-differentiated gastric cancers was assessed by using the area under the receiver operating characteristic curve (AUC).

RESULTS

There were significant differences in the 5^th , 10^th , 25^th , and 50^th percentiles, skew, and kurtosis between poorly and well-differentiated gastric cancers (P < 0.05). There were correlations between the degrees of differentiation and histogram parameters, including the 10^th percentile, skew, kurtosis, and max frequency; the correlation coefficients were 0.273, -0.361, -0.339, and -0.370, respectively. Among all the histogram parameters, the max frequency had the largest AUC value, which was 0.675.

CONCLUSION

Histogram analysis of the ADC maps on the basis of the entire tumor volume can be useful in differentiating between histological grades for gastric cancer.

LEVEL OF EVIDENCE

4 J. Magn. Reson. Imaging 2017;45:440-449.

Diffusion-weighted whole-body imaging with background body signal suppression/T2-weighted image fusion of gastrointestinal cancers

Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) yields positive results for cancer against the surrounding tissues. The combination of DWIBS and T2-weighted images (DWIBS/T2) in the diagnosis of gastrointestinal tract cancers was retrospectively analyzed in the present study. Patients were subjected to magnetic resonance imaging after cancer was diagnosed through specimens obtained via biopsy or endoscopic mucosal resection. Sixteen patients were assessed between July, 2012 and June, 2013 and the correlation between detection with DWIBS/T2 and T staging was analyzed. Regarding patients who underwent surgery, the correlation between detection with DWIBS/T2 and the diameter or depth of invasion was analyzed. All cancers that had advanced to >T2 stage were detectable by DWIBS/T2, whereas all cancers staged as <T1 were not (P<0.0001). Tumors that were undetected by DWIBS/T2 had a mean diameter of 1.53±0.25 cm, whereas those detected had a mean diameter of 3.63±1.88 cm; however, the difference was not statistically significant (P=0.1053). Cancers invading beyond the muscularis propria were detectable by DWIBS/T2, while those which had not invaded the mucosa were not (P=0.0476). In conclusion, DWIBS/T2 was able to positively identify gastrointestinal tract cancers at an advanced stage (>T2) or invading beyond the muscularis propria.

Correlation between apparent diffusion coefficients and HER2 status in gastric cancers: pilot study

Background

To evaluate whether apparent diffusion coefficient (ADC) value of gastric cancer obtained from diffusion weighted imaging (DWI) correlates with the HER2 status.

Methods

Forty-five patients, who had been diagnosed with gastric cancer through biopsy, were enrolled in this IRB-approved study. Each patient underwent a DWI (b values: 0 and 1,000 sec/mm²) prior to surgery (curative gastrectomy or palliative resection). Postoperative microscopic findings, HER2 status by immunohistochemical analysis and fluorescence in situ hybridization (FISH) were obtained. HER2 status was compared among gastric cancers with various histopathological features using the chi square test. The ADC values of gastric cancers with positive and negative HER2 were compared using the student t test.

Results

A weak yet significant correlation was observed between the mean ADC values and HER2 status (r = 0.312, P = 0.037) and scores (r = 0.419, P = 0.004). The mean ADC value of HER2-positive gastric cancers was significantly higher than those of HER2-negative tumors (1.211 vs. 0.984 mm²/s, P = 0.020). The minimal ADC value of HER2-positive gastric cancers was significantly higher than those of HER2-negative tumors (1.105 vs. 0.905 × 10⁻³ mm²/s, P = 0.036).

Conclusions

In this pilot study, we have demonstrated that the ADC values of gastric cancer correlate with the HER2 status. Future research is warranted to see if DWI can predict HER2 status and help in tailoring therapy for gastric cancer.

Diffusion MRI on lymph node staging of gastric adenocarcinoma

OBJECTIVE

The purpose of this study was to evaluate the accuracy of diffusion weighted magnetic resonance imaging (MRI) in preoperative assessment of metastatic lymph nodes of gastric cancer.

METHODS

A total of 23 gastric cancer patients with a mean age of 59.4±10.9 years were analyzed. Lymph nodes were grouped as perigastric lesser curvature (Group Ia), perigastric greater curvature (Group Ib), D1+/D2 lymph nodes (Group II). Identification of histologically metastatic lymph nodes by diffusion weighted MRI was regarded as the main outcome.

RESULTS

A total of 1,056 lymph nodes including 180 histologically proven metastatic lymph nodes were dissected. Although diffusion weighted MRI could identify the metastatic lymph nodes in 18 out of 23 patients (77.8%), only 69 of total 1,056 nodes (6.53%), either metastatic or non-metastatic, could be detected. There was no correlation between histopathology and diffusion weighted MRI with regard to lymph node groups (P>0.05 for all). Overall accuracy was calculated as 69.56, 65.21 and 52.17 for Groups II, Ib and Ia lymph nodes, respectively. Apparent diffusion coefficient (ADC) values could not be helpful to differentiate metastatic lymph nodes (P=0.673).

CONCLUSIONS

Diffusion weighted MRI has low accuracy to detect or to differentiate metastatic and non-metastatic lymph nodes based on their ADC values in gastric cancer.

The utility of MRI for pre-operative T and N staging of gastric carcinoma: a systematic review and meta-analysis

OBJECTIVE

To perform a meta-analysis and literature review regarding the diagnostic accuracy of MRI for pre-operative tumour depth invasion (T) and regional lymph node invasion (N) staging of gastric carcinoma (GC).

METHODS

Articles were identified through systematic search of Medline, PubMed, Cochrane Library, Web of Science, Springerlink and several Chinese databases. The study quality was assessed by the quality assessment for studies of diagnostic accuracy. 2 reviewers independently extracted and assessed the data from 11 eligible studies. A meta-analysis was then carried out. Subgroup and sensitivity analyses were also performed.

RESULTS

11 studies (439 patients) were finally included in the current review. Among these studies, the significant evidence of heterogeneity was only discovered for specificity in T4 stage (I(2) = 59.8%). Pooled sensitivity and specificity of MRI to diagnose T stage tumour (T3-4 vs T1-2) were 0.93 [95% confidence interval (CI), 0.89-0.96] and 0.91 (95% CI, 0.87-0.95), respectively. Pooled estimates of sensitivity and specificity of MRI to diagnose N stage tumour (N0 vs N+) were 0.86 (95% CI, 0.80-0.92) and 0.67 (95% CI, 0.54-0.79), respectively. Subgroup analyses showed that diffusion-weighted imaging was more helpful for T staging.

CONCLUSION

The present systematic review suggests that MRI has a good diagnostic accuracy for pre-operative T staging of GC and should be widely used in clinical work. However, the ability for N staging is relatively poor on MRI.

ADVANCES IN KNOWLEDGE

In the pre-operative staging of GC, MRI was a useful tool and may enhance accuracy for the T staging of advanced GC.

New approaches to gastric cancer staging: Beyond endoscopic ultrasound, computed tomography and positron emission tomography

Currently, there is no single gold standard modality for staging of gastric cancer and several methods have been used complementarily in the each clinical situation. To make up for the shortcomings of conventional modalities such as endoscopic ultrasound, computed tomography and ¹⁸F-fluoro-2-deoxyglucose positron emission tomography, numerous attempts with new approaches have been made for gastric cancer staging. For T staging, magnifying endoscopy with narrow-band was evaluated to differentiate mucosal cancer from submucosal cancer. Single/double contrast-enhanced ultrasound and diffusion-weighted magnetic resonance imaging were also tried to improve diagnostic accuracy of gastric cancer. For intraoperative staging with sentinel node mapping, indocyanine green infrared and fluorescence imaging was introduced. In addition, to detect micrometastasis, real-time reverse transcription-polymerase chain reaction system with multiple markers was studied. Staging laparoscopy using 5-aminolevulinic acid-mediated photodynamic diagnosis and percutaneous diagnostic peritoneal lavage were also evaluated. However, most studies reporting new staging methods is preliminary and further studies for validation in clinical practice are needed. In this mini-review, we discuss new progress in gastric cancer staging. Especially, we focus on new diagnostic approach to gastric cancer staging beyond the conventional modalities and briefly review the remarkable clinical results of the studies published over the past three years.

Apparent diffusion coefficient value of gastric cancer by diffusion-weighted imaging: correlations with the histological differentiation and Lauren classification

OBJECTIVE

The purpose of this study was to evaluate the correlations between histological differentiation and Lauren classification of gastric cancer and the apparent diffusion coefficient (ADC) value of diffusion weighted imaging (DWI).

MATERIALS AND METHODS

Sixty-nine patients with gastric cancer lesions underwent preoperative magnetic resonance imaging (MRI) (3.0T) and surgical resection. DWI was obtained with a single-shot, echo-planar imaging sequence in the axial plane (b values: 0 and 1000s/mm(2)). Mean and minimum ADC values were obtained for each gastric cancer and normal gastric walls by two radiologists, who were blinded to the histological findings. Histological type, degree of differentiation and Lauren classification of each resected specimen were determined by one pathologist. Mean and minimum ADC values of gastric cancers with different histological types, degrees of differentiation and Lauren classifications were compared. Correlations between ADC values and histological differentiation and Lauren classification were analyzed.

RESULTS

The mean and minimum ADC values of gastric cancers, as a whole and separately, were significantly lower than those of normal gastric walls (all p values <0.001). There were significant differences in the mean and minimum ADC values among gastric cancers with different histological types, degrees of differentiation and Lauren classifications (p<0.05). Mean and minimum ADC values correlated significantly (all p<0.001) with histological differentiation (r=0.564, 0.578) and Lauren classification (r=-0.493, -0.481).

CONCLUSIONS

The ADC values may be helpful as a noninvasive tool for evaluating the histological features of gastric cancer, such as histological type, degree of differentiation and Lauren classification.