Joon Seok Lim

Added Value of Gadoxetic Acid-enhanced Hepatobiliary Phase MR Imaging in the Diagnosis of Hepatocellular Carcinoma

PURPOSE To determine the added value of hepatobiliary phase images in gadoxetic acid-enhanced magnetic resonance (MR) imaging in the evaluation of hepatocellular carcinoma (HCC). MATERIALS AND METHODS Institutional review board approved this retrospective study and waived the informed consent. Fifty-nine patients with 84 HCCs underwent gadoxetic acid-enhanced MR examinations that included 20-minute delayed hepatobiliary phase imaging. MR imaging was performed with a 1.5-T system in 19 patients and a 3.0-T system in 40 patients. A total of 113 hepatic nodules were documented for analysis. Three radiologists independently reviewed two sets of MR images: set 1, unenhanced (T1- and T2-weighted) and gadoxetic acid-enhanced dynamic images; set 2, hepatobiliary phase images and unenhanced and gadoxetic acid-enhanced dynamic images. For each observer, the diagnostic accuracy was compared by using the area under the alternative free-response receiver operating characteristic curve (A(z)). Sensitivity and specificity were also calculated and compared between the two sets. RESULTS For all observers, A(z) values were higher with the addition of the hepatobiliary phase. The observer who had the least experience in abdominal imaging (2 years) demonstrated significant improvement in A(z), from 0.895 in set 1 to 0.951 in set 2 (P = .049). Sensitivity increased with the addition of hepatobiliary phase images but did not reach statistical significance. Nine HCCs (10.7%) in six patients (10.1%) were seen only on hepatobiliary phase images. CONCLUSION Hepatobiliary phase images obtained after gadoxetic acid-enhanced dynamic MR imaging may improve diagnosis of HCC and assist in surgical planning.

Restaging of Rectal Cancer with MR Imaging after Concurrent Chemotherapy and Radiation Therapy

In patients with rectal cancer who have received concurrent chemotherapy and radiation therapy (CCRT) before surgery, magnetic resonance (MR) imaging has low accuracy in prediction of the pathologic stage owing to overstaging or understaging. The factors related to this problem include fibrosis, desmoplastic reaction, edema, inflammation, and viable tumor nets at a fibrotic scar from a previous tumor. Preoperative diagnosis with MR imaging of histologic variants of rectal adenocarcinoma, especially mucinous adenocarcinoma, is important because these variants tend to have a poor response to CCRT. In addition, these variants manifest with high signal intensity on T2-weighted images after CCRT; this finding makes it difficult to differentiate residual tumors from remaining mucin pools. MR volumetry and functional MR imaging may be helpful in prediction and assessment of tumor response to CCRT. Awareness of post-CCRT changes helps radiologists achieve appropriate restaging of irradiated rectal cancer with MR imaging and can lead to a reduction in understaging or overstaging. It is important to obtain and compare both pre- and post-CCRT images before interpreting the post-CCRT images.

Tumor Volume Changes Assessed by Three-Dimensional Magnetic Resonance Volumetry in Rectal Cancer Patients After Preoperative Chemoradiation: The Impact of the Volume Reduction Ratio on the Prediction of Pathologic Complete Response

PURPOSE The aim of this study was to determine the correlation between tumor volume changes assessed by three-dimensional (3D) magnetic resonance (MR) volumetry and the histopathologic tumor response in rectal cancer patients undergoing preoperative chemoradiation therapy (CRT). METHODS AND MATERIALS A total of 84 patients who underwent preoperative CRT followed by radical surgery were prospectively enrolled in the study. The post-treatment tumor volume and tumor volume reduction ratio (% decrease ratio), as shown by 3D MR volumetry, were compared with the histopathologic response, as shown by T and N downstaging and the tumor regression grade (TRG). RESULTS There were no significant differences in the post-treatment tumor volume and the volume reduction ratio shown by 3D MR volumetry with respect to T and N downstaging and the tumor regression grade. In a multivariate analysis, the tumor volume reduction ratio was not significantly associated with T and N downstaging. The volume reduction ratio (>75%, p = 0.01) and the pretreatment carcinoembryonic antigen level (< or =3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (< or = 5 ml), were, however, significantly associated with an increased pathologic complete response rate. CONCLUSION More than 75% of the tumor volume reduction ratios were significantly associated with a high pathologic complete response rate. Therefore, limited treatment options such as local excision or simple observation might be considered after preoperative CRT in this patient population.

Comparison of CT and 18F-FDG pet for detecting peritoneal metastasis on the preoperative evaluation for gastric carcinoma.

Objective The aim of our study was to compare the accuracy of CT and 18F-FDG PET for detecting peritoneal metastasis in patients with gastric carcinoma. Materials and Methods One-hundred-twelve patients who underwent a histologic confirmative exam or treatment (laparotomy, n = 107; diagnostic laparoscopy, n = 4; peritoneal washing cytology, n = 1) were retrospectively enrolled. All the patients underwent CT and 18F-FDG PET scanning for their preoperative evaluation. The sensitivities, specificities and accuracies of CT and 18F-FDG PET imaging for the detection of peritoneal metastasis were calculated and then compared using Fishers exact probability test (p < 0.05), on the basis of the original preoperative reports. In addition, two board-certified radiologists and two board-certified nuclear medicine physicians independently reviewed the CT and PET scans, respectively. A receiver-operating characteristic curve analysis was performed to compare the diagnostic performance of CT and 18F-FDG PET imaging for detecting peritoneal metastasis. Results Based on the original preoperative reports, CT and 18F-FDG PET showed sensitivities of 76.5% and 35.3% (p = 0.037), specificities of 91.6% and 98.9% (p = 0.035), respectively, and equal accuracies of 89.3% (p = 1.0). The receptor operating characteristics curve analysis showed a significantly higher diagnostic performance for CT (Az = 0.878) than for PET (Az = 0.686) (p = 0.004). The interobserver agreement for detecting peritoneal metastasis was good (κ value = 0.684) for CT and moderate (κ value = 0.460) for PET. Conclusion For the detection of peritoneal metastasis, CT was more sensitive and showed a higher diagnostic performance than PET, although CT had a relatively lower specificity than did PET.

Typical and atypical manifestations of serous cystadenoma of the pancreas: imaging findings with pathologic correlation.

OBJECTIVE The purpose of this article is to present the typical and atypical manifestations of serous cystadenoma, which can be visualized with cross-sectional imaging. CONCLUSION Serous cystadenomas of the pancreas have various distinguishing imaging features. Typically, a serous cystadenoma is morphologically classified as having either a polycystic, honeycomb, or oligocystic pattern. Atypical manifestations of serous cystadenoma can include giant tumors with ductal dilatation, intratumoral hemorrhages, solid variants, unilocular cystic tumors, interval growth, and a disseminated form.

Perfusion MRI for the prediction of treatment response after preoperative chemoradiotherapy in locally advanced rectal cancer

ObjectivesTo evaluate the utility of perfusion MRI as a potential biomarker for predicting response to chemoradiotherapy (CRT) in locally advanced rectal cancer.MethodsThirty-nine patients with primary rectal carcinoma who were scheduled for preoperative CRT were prospectively recruited. Perfusion MRI was performed with a 3.0-T MRI system in all patients before therapy, at the end of the 2nd week of therapy, and before surgery. The Ktrans (volume transfer constant) and Ve (extracellular extravascular space fraction) were calculated.ResultsBefore CRT, the mean tumour Ktrans in the downstaged group was significantly higher than that in the non-downstaged group (P = 0.0178), but there was no significant difference between tumour regression grade (TRG) responders and TRG non-responders (P = 0.1392). Repeated-measures analysis of variance (ANOVA) showed significant differences for evolution of Ktrans values both between downstaged and non-downstaged groups (P = 0.0215) and between TRG responders and TRG non-responders (P = 0.0001). Regarding Ve, no significant differences were observed both between downstaged and non-downstaged groups (P = 0.689) or between TRG responders and TRG non-responders (P = 0.887).ConclusionPerfusion MRI of rectal cancer can be useful for assessing tumoural Ktrans changes by CRT. Tumours with high pre-CRT Ktrans values tended to respond favourably to CRT, particularly in terms of downstaging criteria.Key Points• Perfusion MRI can now assess therapeutic response of tumours to therapy.• Tumours with high initialKtransvalues responded favourably to chemoradiotherapy.• Perfusion MRI of rectal cancer may help with decisions about management.

Accuracy of gadoxetic acid-enhanced magnetic resonance imaging for the diagnosis of sinusoidal obstruction syndrome in patients with chemotherapy-treated colorectal liver metastases

AbstractObjectiveTo assess whether reticular hypointensity on hepatobiliary phase images of gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) is a diagnostic finding of sinusoidal obstruction syndrome (SOS) in patients with hepatic metastases who have undergone chemotherapy.MethodsWe retrospectively analysed EOB-MRI of 42 patients who had undergone chemotherapy before hepatic resection of colorectal hepatic metastases. Two radiologists, who were unaware of whether or not the patients had SOS, reviewed the hepatobiliary phase images to determine the presence of hypointense reticulation in the liver using a 5-point scale. The sensitivity, specificity and area under the receiver operating characteristics curve (Az) were calculated for each reviewer.ResultsThe sensitivity, specificity and Az for the diagnosis of SOS were 75%, 100% and 0.957 for reader 1 and 75%, 96.2% and 0.936 for reader 2, respectively. In one patient who received a false-positive diagnosis by one reader, there was sinusoidal fibrosis on histological examination, but not diagnostic for SOS. False-negative diagnosis occurred in four patients for both readers; histology of these patients showed minimal and localised sinusoidal congestion and fibrosis.ConclusionsReticular hypointensity on hepatobiliary phase images of EOB-MRI is highly specific for the diagnosis of SOS in patients with treated colorectal hepatic metastases.Key Points• Gadoxetic acid enhanced magnetic resonance imaging (EOB-MRI) can identify the sinusoidal obstruction syndrome (SOS) • The diagnosis can be achieved with high specificity and good interobserver agreement. • SOS typically demonstrates diffuse hypointensity on hepatobiliary phase images on EOB-MRI. • EOB-MRI may be falsely negative in patients with minimal degree of SOS.

Diagnostic accuracy of multidetector row computed tomography in T- and N staging of gastric cancer with histopathologic correlation.

Purpose: To evaluate the diagnostic accuracy of multidetector row computed tomography (MDCT) for the preoperative T- and N staging of gastric cancer. Materials and Methods: Eighty-four consecutive patients with gastric cancer underwent preoperative MDCT. Except for 15 patients who did not undergo surgery, 69 patients were included in our study. Two radiologists independently evaluated the T- and N staging on the axial CT images alone and in combination with the MPR images. For N staging, the new TNM and Japanese classifications were independently used. Differences in staging accuracy for T- and N staging were assessed using the McNemar test. Results: The overall T staging accuracy of the axial and combined axial and MPR images was as follows: 67% (47 of 70 cancers) versus 77% (54 of 70 cancers) (P = 0.039). The overall N staging accuracy of the axial and combined axial and MPR images was as follows: 59% (41 of 69 cancers) versus 67% (46 of 69 cancers) (P = 0.180, Japanese classification) and 54% (37 of 69 cancers) versus 59% (41 of 69 cancers) (P = 0.109, TNM classification). Conclusions: Using MPR images enables more accurate preoperative T staging of gastric cancer, but not for N staging in either classification system.

Laparoscopic Spleen-Preserving Splenic Hilar Lymph Node Dissection During Total Gastrectomy for Gastric Cancer

I R erie N d 1 or T is in e tre l assif ndos ic o the f ogr I ively, o . Ind ilar L ith a h oper m tasis a eopera ope just plenectomy has been at issue for many years in the f astric cancer operations especially for treatment of pr al gastric cancer. In total gastrectomy, splenic hilar ly ode (LN) should be removed for a D2 LN dissectio 1 In ddition, LNs along splenic vessels (station 11) or sp ilar area (splenic 10) LN involvement is seen in as m 6% of patients with cancers of the proximal or w tomach. Although pancreatosplenectomy was advocated f omplete removal of LNs along the splenic vessels plenic hilum, it had been proved that pancreas-preser otal gastrectomy that includes splenectomy has the s ongterm surgical outcomes compared, with pancrea plenectomy with a lower rate of postoperative morbid 6

Rectal Cancer: Comparison of Accuracy of Local-Regional Staging with Two- and Three-dimensional Preoperative 3-T MR Imaging

PURPOSE To compare the local-regional staging accuracy of the conventional two-dimensional (2D) T2-weighted imaging protocol and of the three-dimensional (3D) T2-weighted imaging protocol for preoperative magnetic resonance (MR) imaging in rectal cancer patients. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and a waiver of informed consent was obtained. A review was conducted of 109 preoperative 3-T MR images obtained with 2D and 3D T2-weighted imaging protocols in rectal cancer patients. Two radiologists independently assessed the radiologic findings for T and N category lesions, conspicuity of tumor margin, and image quality of 2D and 3D data. Interactive multiplanar reconstruction was performed for 3D data analysis. The linear weighted kappa values for T2-weighted imaging staging results (2D and 3D data) and histopathologic staging results were calculated and compared. Wilcoxon signed rank test was performed to compare tumoral conspicuity and overall image quality. RESULTS T category lesion staging accuracy values for 2D and 3D data, respectively, were 66.0% and 67.0% for reviewer 1 (P = .465) and 63.3% and 56.9% for reviewer 2 (P = .402). N category lesion staging accuracy values for 2D and 3D T2-weighted images, respectively, were 64.2% and 57.8% for reviewer 1 (P = .427) and 47.7% and 62.4% for reviewer 2 (P = .666). Tumor conspicuity was better for 2D T2-weighted imaging, but no significant difference in image quality was observed. CONCLUSION Preoperative MR imaging in rectal cancer patients for staging with conventional 2D and multiplanar reconstruction 3D T2-weighted imaging protocols showed no significant differences in accuracy of T and N category staging and overall image quality, as determined by degree of artifact. However, the 3D T2-weighted imaging protocol had limitations in regard to lesion conspicuity.