Perfusion of hepatocellular carcinomas measured by diffusion-derived vessel density biomarker: Higher hepatocellular carcinoma perfusion than earlier intravoxel incoherent motion reports.

Diffusion-derived vessel density (DVDD) is a physiological surrogate of the area of microvessels per unit tissue area. DDVD is calculated according to DDVD(b0b2) = Sb0/ROIarea0 - Sb2/ROIarea2, where Sb0 and Sb2 refer to the liver signal when b is 0 or 2 s/mm2. Pathohistological studies and contrast-enhanced CT/MRI data showed higher blood volume in hepatocellular carcinoma (HCC) relative to native liver tissue. With intravoxel incoherent motion (IVIM) imaging, most authors paradoxically reported a decreased perfusion fraction of HCC relative to the adjacent liver. This study applied DDVD to assess the perfusion of HCC. MRI was performed with a 3.0-T magnet. Diffusion-weighted images with b-values of 0 and 2 s/mm2 were acquired in 72 HCC patients. Thirty-two patients had microvascular invasion (MVI(+)) and 40 patients did not have microvascular invasion (MVI(-)). Fifty-eight patients had Edmondson-Steiner grade I or II HCC, and 14 patients had Edmondson-Steiner grade III or IV HCC. DDVD measurement was conducted on the axial slice that showed the largest HCC size. DDVD(b0b2) T/L = HCC DDVD(b0b2)/liver DDVD(b0b2). DDVD(b0b2) T/L median (95% confidence interval) of all HCCs was 2.942 (2.419-3.522), of MVI(-) HCCs was 2.699 (2.030-3.522), of MVI(+) HCCs was 2.988 (2.423-3.990), of Edmondson-Steiner grade I/II HCCs was 2.873 (2.277-3.465), and of Edmondson-Steiner grade III/IV HCCs was 3.403 (2.008-4.485). DDVD(b0b2) T/L approximately agrees with contrast agent dynamically enhanced CT/MRI literature data, whereas it differs from earlier IVIM study results, where HCC perfusion fraction was paradoxically lower relative to native liver tissue. A weak trend was noted with MIV(+) HCCs had a higher DDVD(b0b2) T/L than that of MVI(-) HCCs, and a weak trend was noted with the poorly differentiated group of HCCs (Edmondson-Steiner grade III and IV) had a higher DDVD(b0b2) T/L than that of the better differentiated group of HCCs (Edmondson-Steiner grade I and II).

Repeatability and reproducibility comparisons of liver IVIM imaging with free-breathing or respiratory-triggered sequences.

For liver intravoxel incoherent motion (IVIM) data acquisition, respiratory-triggering (RT) MRI is commonly used, and there are strong motivations to shorten the scan duration. For the same scan duration, more b values or higher numbers of excitations can be allowed for free-breathing (FB) imaging than for RT. We studied whether FB can be used to replace RT when careful IVIM image acquisition and image processing are conducted. MRI data of 22 healthy participants were acquired using a 3.0 T scanner. Diffusion imaging was based on a single-shot spin-echo-type echo-planar sequence and 16 b values of 0, 2, 4, 7, 10, 15, 20, 30, 46, 60, 72, 100, 150, 200, 400, and 600 s/mm2 . Each subject attended two scan sessions with an interval of 10-20 days. For each scan session, a subject was scanned twice, first with RT and then with FB. The mean image acquisition time was 5.4 min for FB and 10.8 min for RT. IVIM parameters were calculated with bi-exponential model segmented fitting with a threshold b value of 60 s/mm2 , and fitting started from b = 2 s/mm2 . There was no statistically significant difference between IVIM parameters measured with FB imaging or RT imaging. Perfusion fraction ICC (intraclass correlation coefficient) for FB imaging and RT imaging in the same scan session was 0.824. For perfusion fraction, wSD (within-subject standard deviation), BA (Bland-Altman) difference, BA 95% limit, and ICC were 0.022, 0.0001, -0.0635~0.0637, and 0.687 for FB and 0.031, 0.0122, -0.0723~0.0967, and 0.611 for RT. For Dslow (×10-3  s/mm2 ), wSD, BA difference, BA 95% limit, and ICC were 0.057, 0.0268, -0.1258~0.1793, and 0.471 for FB and 0.073, -0.0078, -0.2170-0.2014, and <0.4 for RT. The Dfast coefficient of variation was 0.20 for FB imaging and 0.28 for RT imaging. All reproducibility indicators slightly favored FB imaging.

Magnetic Resonance Deep Learning Radiomic Model Based on Distinct Metastatic Vascular Patterns for Evaluating Recurrence-Free Survival in Hepatocellular Carcinoma.

BACKGROUND: The metastatic vascular patterns of hepatocellular carcinoma (HCC) are mainly microvascular invasion (MVI) and vessels encapsulating tumor clusters (VETC). However, most existing VETC-related radiological studies still focus on the prediction of VETC status. PURPOSE: This study aimed to build and compare VETC-MVI related models (clinical, radiomics, and deep learning) associated with recurrence-free survival of HCC patients. STUDY TYPE: Retrospective. POPULATION: 398 HCC patients (349 male, 49 female; median age 51.7 years, and age range: 22-80 years) who underwent resection from five hospitals in China. The patients were randomly divided into training cohort (n = 358) and test cohort (n = 40). FIELD STRENGTH/SEQUENCE: 3-T, pre-contrast T1-weighted imaging spoiled gradient recalled echo (T1WI SPGR), T2-weighted imaging fast spin echo (T2WI FSE), and contrast enhanced arterial phase (AP), delay phase (DP). ASSESSMENT: Two radiologists performed the segmentation of HCC on T1WI, T2WI, AP, and DP images, from which radiomic features were extracted. The RFS related clinical characteristics (VETC, MVI, Barcelona stage, tumor maximum diameter, and alpha fetoprotein) and radiomic features were used to build the clinical model, clinical-radiomic (CR) nomogram, deep learning model. The follow-up process was done 1 month after resection, and every 3 months subsequently. The RFS was defined as the date of resection to the date of recurrence confirmed by radiology or the last follow-up. Patients were followed up until December 31, 2022. STATISTICAL TESTS: Univariate COX regression, least absolute shrinkage and selection operator (LASSO), Kaplan-Meier curves, log-rank test, C-index, and area under the curve (AUC). P < 0.05 was considered statistically significant. RESULTS: The C-index of deep learning model achieved 0.830 in test cohort compared with CR nomogram (0.731), radiomic signature (0.707), and clinical model (0.702). The average RFS of the overall patients was 26.77 months (range 1-80 months). DATA CONCLUSION: MR deep learning model based on VETC and MVI provides a potential tool for survival assessment. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 3.

Pelvic Ultrasound in Diagnosing and Evaluating the Efficacy of Gonadotropin-Releasing Hormone Agonist Therapy in Girls With Idiopathic Central Precocious Puberty.

Background and Objective: Idiopathic central precocious puberty (ICPP) is characterized by early pubertal changes, the acceleration of growth velocity, and rapid bone maturation that often results in reduced adult height. Gonadotrophin-releasing hormone agonist (GnRHa) is currently considered to be an effective therapeutic agent. At present, GnRH stimulation test is adopted as a gold standard for the diagnosis of ICPP and the efficacy evaluation of GnRHa therapy. However, it is difficult to operate in practice due to the cumbersome procedures and multiple blood samples required. This study was conducted to establish the value of pelvic ultrasound in diagnosing ICPP and evaluating the efficacy of GnRHa therapy. Materials and Methods: One hundred and twenty-two girls with ICPP (ICPP group) were enrolled in the study. Pelvic ultrasound and levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were examined before and after GnRHa therapy for 3 months. Eighty normal prepubertal girls were enrolled as the control group. The difference in pelvic ultrasound parameters between the ICPP group before GnRHa therapy and the control group was compared by independent-sample t-test, while paired t-test for ICPP group before and after GnRHa therapy. Receiver operating characteristic (ROC) curve was used to explore the optimal pelvic ultrasound parameters for diagnosing ICPP. Pearson correlation analysis was performed between the pelvic ultrasound parameters and serum sexual hormone level. Results: The pelvic ultrasound parameters (length of the uterine body, anteroposterior diameter of the uterine body, transverse diameter of the uterine body, volume of the uterine body, uterine body-cervix ratio, length of the ovary, transverse diameter of the ovary, anteroposterior diameter of the ovary, volume of the ovary, number of increased follicles and maximum diameter of the follicle) in the ICPP group before GnRHa therapy were significantly larger than those of the control group (P < 0.05). All the above pelvic ultrasound parameters in the ICPP group were significantly decreased after GnRHa therapy compared with those before treatment (P < 0.05). The volume of the uterine body had the largest area under the ROC curve in differentiating between patients with ICCP and the control group. Pelvic ultrasound parameters were significantly correlated with serum sexual hormone levels (P < 0.05). Conclusion: This study indicates pelvic ultrasound is a simple and reliable tool to diagnose ICPP and evaluates the efficacy of GnRHa therapy by dynamically observing the morphology of internal genitalia. The volume of uterine body was the best ultrasound parameter to distinguish patients with ICPP from normal girls.

Determinants of crease width in inherent double eyelid of Asian young women.

BACKGROUND: The creation of a superior palpebral crease has been the most popular plastic surgery procedure in Asians for several decades. The most important criterion for judging the success of this procedure is the achievement of the desired size and shape of this crease or the perfect crease width. However, the determinants of crease width remain unclear, which may account for the high rate of unsatisfactory results. METHODS: Standard images were used to study the anatomic parameters, including crease width, crease height, and upper eyelid movement distance (ULMD) at the midpupillary axis, of the inherent double eyelid crease in 32 Chinese women aged 19-26 years. The thickness of the eyelid tissue at 5, 7.5, 10, and 15 mm from the lid margin was measured in the oblique sagittal direction by magnetic resonance imaging (MRI) at the central axis of the optic nerve. Multiple linear regression was used to analyze the relationship between crease width and crease height, ULMD, and eyelid thickness. RESULTS: Multiple linear regression revealed that crease height, crease thickness, and ULMD were significantly associated with crease width (partial regression coefficients: 0.67, -0.33, and -0.29 respectively). The determination coefficient R2 was 0.667 in the regression model, and the result of analysis of variance (ANOVA) showed that the regression model was significant (F = 16.04, p = 0.000). CONCLUSIONS: In performing upper blepharoplasty, it is important to consider eyelid thickness and movement distance of the upper eyelid margin rather than relying on crease height alone. Attention to these factors will help to achieve the desired size and shape of the crease.

Double contrast-enhanced ultrasonography in the detection of periampullary cancer: Comparison with B-mode ultrasonography and MR imaging.

PURPOSE: To investigate the value of double contrast-enhanced ultrasonography (DCEUS) in the detection of periampullary cancer. MATERIALS AND METHODS: Ninety-nine patients with surgery or biopsy-proven periampullary cancer who underwent both DCEUS and magnetic resonance imaging (MRI) examinations before operation were enrolled in our study. DCEUS in which intravenous microbubbles were used in combination with oral contrast agent and MRI were performed preoperatively to make a detection diagnosis of periampullary cancer. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of DCEUS, B-mode ultrasonography (BUS) and MRI were calculated and compared. Receiver operating characteristic (ROC) curves were used to evaluate the accuracy of BUS, DCEUS and MRI in the detection. Stratified analyses were performed for different pathological types and different sizes of periampullary lesions. The inter- and intra-observer reliability of DCEUS for cancer detection was also investigated. RESULT: There were no significant differences in sensitivity, specificity, PPV, NPV or accuracy between DCEUS and MRI (all P>0.05). ROC analysis showed that the accuracy of DCEUS or MRI was higher than that of BUS (P<0.001), while no significant differences were noted in the accuracy between DCEUS and MR. In the 76 cases of periampullary cancer, DCEUS appeared to be superior to BUS for ampullary carcinoma, duodenum carcinoma and for lesions with an average diameter of less than 3cm. DCEUS appeared equal to BUS in other groups. No significant differences were noted between DCEUS and MRI in the stratified analysis. A considerably well agreement between DCEUS and MRI was obtained using Kappa analysis (k=0.649, P<0.001). The intra- and inter-observer reproducibility were both good for detection of periampullary cancer by DCEUS, with a Kappa values of 0.783 (P<0.01) and 0.732 (P<0.01), respectively. CONCLUSION: DCEUS provides an available and useful imaging modality in the detection of periampullary cancer. This technique can aid in displaying the invisible periampullary region in BUS and may also become an effective supplemental method to MRI.

Benign pericardial schwannoma in a Chinese woman: a case report.

BACKGROUND: Intrathoracic schwannomas are most frequently located in the posterior mediastinum. A Chinese woman presented with a benign pericardial schwannoma in the pretracheal space and aortopulmonary window, a location which has not been described previously in the literature. CASE PRESENTATION: A 50-year-old Chinese woman initially reported a cough associated with a small amount of sputum. Contrast-enhanced computed tomography (CT) subsequently revealed a 9 × 11 cm2 lobulated mass with sharp margins that presented as a capsule with heterogeneous enhancement and punctate calcification. Complete surgical resection was performed using a thoracotomy approach. The resected intrapericardial tumor was a firm, large mass with lobulation. Capsulation prevented infiltration of the mass into adjacent organs. Pathological examination verified that the tumor was a benign pericardial schwannoma. CONCLUSION: This is the first reported case of a benign pericardial schwannoma located in the pretracheal space and aortopulmonary window. While a contrast-enhanced CT scan was able to differentiate this pericardial schwannoma from other middle mediastinal tumors, the exact diagnosis and plan for treatment depended on a pathological examination. For similar cases involving pericardial schwannomas, complete surgical resection is recommended, particularly for the prevention of life-threatening cardiopulmonary complications.

[Magnetic resonance myocardial perfusion imaging for evaluating myocardial viability after myocardial infarction].

OBJECTIVE: To assess the value of magnetic resonance (MR) myocardial perfusion imaging (MRMPI) in evaluating the myocardial viability in patients with myocardial infarction. METHODS: MRMPI was performed in 51 patients with myocardial infarction using a 1.5 T MR scanner. All the patients were examined using IR-turbo FLASH sequence during the first-pass and delayed phase 5-30 min after injection of 0.1 mmol/kg Gd-DTPA at the rate of 4 ml/s. The short axis images were acquired during the first-pass, and both the short axis and long axis images were obtained during the delayed phase. The left ventricular wall on the short-axis slice was divided into 8 segments. A correlative study of the results of the rest and stress (99m)Tc single photon emission computed tomography (SPECT) was carried out in 21 patients. RESULTS: In the 51 patients with myocardial infarction, 42(82.3%) showed hypoperfusion during the first-pass imaging and 50(98%) had delayed hyperenhancement. In the 21 patients receiving SPECT, 48 nonviable segments was detected among the 168 segments scanned by (99m)TcSPECT, and MRMPI showed delayed hyperenhancement in all the infracted areas. Of the 120 viable segments detected by rest and stress (99m)Tc SPECT, 97 segments (80.8%) were found to be free of delayed hyperenhancement by MRMPI. With the rest and stress (99m)Tc SPECT as the reference, the sensitivity and the specificity of MRMPI were 100.0% and 80.8%, respectively. CONCLUSION: MRMPI allows effective identification of the myocardial viability and nonviability as well as the severity and extent of the myocardial infraction.

[Optimization of the scan delay time of 64-slice spiral CT portal venography].

OBJECTIVE: To optimize scan delay time of multi-slice spiral CT portal venography (MSCTP) using test bolus injection. METHODS: Sixty individuals with no hepatic diseases were randomly divided into 4 groups (A, B, C and D). The time-density curves (TDC) of the portal vein (PV) were acquired by test bolus (15 ml, 5 ml/s) at the level of liver hilus. In the 4 groups, the MSCTP were delayed for 4, 6, 8 and 10 s according to the peak time of TDC, respectively. The maximum CT value of the portal vein and liver parenchyma were recorded. The maximum intensity projection (MIP) and volume rendering (VR) were employed for three-dimensional reconstruction and the image quality of the 4 groups was estimated. RESULTS: The average peak time of healthy individuals ranged between 24 and 32 s (95% confidence interval) by means of the test bolus (15 ml). Group C (delay time of 8 s) had a much better image quality of the portal vain than the other groups, and the small branches of the portal vein (6th and 7th orders) were clearly visualized; the major portal vein branches (1st to 4th orders) were also enhanced with sharp edges. Although the hepatic vein was also observed in the portal venous phase in group D, the details of the portal vein on the hepatic edge were distinct and well defined. CONCLUSION: At the injection rate of 5 ml/s, the optimum scan time delayed is 8 to 10 s in normal individuals according to the peak time of the test bolus.

[Preparation of VX2 rabbit hepatoma models and modification of the hepatic artery catheterization technique].

OBJECTIVE: To establish New Zealand rabbit hepatoma models with VX2 cell line, and modify the hepatic artery catheterization technique. METHODS: Forty New Zealand rabbit models bearing hepatoma were established by implanting VX2 cells into the left and right liver lobes. Two weeks after the tumor cell implantation, 26 rabbits in the experimental group underwent modified hepatic artery catheterization procedures using microsurgical technique, and 10 rabbits in the control group were catheterized with 3F micro-catheter using Seldinger technique. The VX2 hepatomas were observed before and after the catheterization with multi-slice spiral CT scan and digital subtractive angiography (DSA). RESULTS: Tumor growth after the tumor cell implantation was confirmed in 36 rabbits by CT scans and open operations. The success rate of catheterization was 88% (23/26) in the experimental group, and 40% (4/10) in the control group. VX2 hepatomas appeared as hypointense or isointense nodules on multi-slice spiral CT, and hepatic artery angiography showed that VX2 hepatomas had homogeneous or nodular tumor staining. CONCLUSION: The modified hepatic artery catheterization using microsurgical technique has higher success rate than catheterization with 3F micro-catheter by Seldinger technique, and significantly decreases X-ray exposure for the staff undertaking the operations.

[Study on the three dimensional hepatic virtual operation based on the data of 64-slice helical CT scanning].

OBJECTIVE: To study the surgery plan and simulation effect of the three dimensional (3D) hepatic virtual operation based on the data of 64-slice helical CT scanning and to probe the feasibility of the virtual operation based on the FreeForm Modeling System. METHODS: The volunteer liver was scanned to collect two dimensional (2D) DICOM data of 64-slice helical CT scanning and the 3D hepatic and intrahepatic vessels model were reconstructed by MIMICS software. The reconstructed liver, the intrahepatic vessels model and the artificial tumor models were output into the FreeForm Modeling System in the STL format. The device PHANTOM with the characterization of dynamo-feedback was applied to make the operation on the 3D hepatic. RESULTS: The spatial relationship between the tumour and the intrahepatic vessels were clearly observed by rotation and enlargement of the target. According to the operation principle, the left lobe of liver resection was simulated by manipulating the device PHANToM. Through the liver transparence surface, the intrahepatic vessels were easily distinguished. The operation procedure was accord with the clinic hepatic surgery. Meanwhile, during the operation, by adjusting the incision objective intensity, the dynamo-feedback intensity was definitely touched. CONCLUSIONS: By using the FreeForm Modeling System,the hepatic operation procedure can be simulated ahead of time. The operation complication in the practical surgery can be anticipated and the individualization operation schema can be reasonable instituted.

[Image segmentation and three-dimensional reconstruction of the liver based on 64-slice spiral CT scanning data].

OBJECTIVE: To study the segmentation methods of the liver CT images and the value of 3-dimensional (3D) reconstruction of the liver in the planning of hepatic surgery. METHODS: The 2D Digital Imaging and Communications in Medicine (DICOM) format data of the liver obtained from healthy volunteers were transformed into bmp format image, and the liver image segmentation was performed using Photoshop software. The 3D model was reconstructed using MIMICS software. RESULTS: The DICOM format data of the liver obtained by 64 slice spiral CT included totally 658 slice images. The segmented liver image showed clear profiles and complete intrahepatic duct data were reserved. The segmented liver images were free of discontinuation during continuous observation. The liver surface and internal ductal system, including the hepatic arteries and veins, and the hepatic portal system and their branches, were represented clearly. The reconstructed liver allowed clear identification of the anatomic landmark and matched the actual liver volume. The reconstructed ductal structure were distinct and continuous with natural texture. The reconstructed liver and the hepatic internal duct system were simultaneously displayed by adjusting the transparency of the liver, and the blood vessels were also represented. CONCLUSION: Segmentation of the liver images in different phases using Photoshop can be feasible for liver reconstruction. The reconstructed liver and the intrahepatic ductal structure allow vivid 3D observation of the spatial relationship among the major tracts and accurate estimation of the liver volume.

[The value of three-dimensional 64-multi-slices helical computer tomography on the diagnosis of diseases of digestive system].

OBJECTIVE: To study the value of three-dimensional 64-slice helical computer tomography (64-MSCT) in diagnosis and surgical treatment on diseases of digestive system. METHODS: From November 2005 to August 2006, 64-MSCT was performed on 102 patients suspected of digestive diseases to display foci of infection, hepatic conduit, biliary-pancreatic duct and portal venous system, followed by three-dimensional reconstruction of those targets. The reconstructed images as well as the data obtained from the reconstruction were compared with the surgical results. RESULTS: Twenty-five of 27 patients with portal hypertension (PHT) showed blur-free imaging of main portal vein (MPV) while the other 2 cases showed congenital cavernous transformation or thrombogenesis of MPV. Compensatory circulation of portal venous system was displayed satisfactorily in 27 cases. The three-dimensionally reconstructed images of 34 cases of hepatocellular carcinoma (HCC) demonstrated no invasion of tumors into the tissues and blood vessels of 23 cases, visible invasion into portal vein and hepatic veins of 9 cases, tumor embolus in portal veins of 1 case, and arterio-venous fistula in only one case. The 3D imaging of biliary passages displayed total concretion, tumor and constrictive or dilated biliary-pancreatic duct and bile duct around amphi-obstruction, which complied with the operations research of calculus of bile duct in 25 cases, cholangiocarcinoma in 5 cases, and cancer of pancreas in 5 cases. Operations research in accordance with the 3D reconstructed imaging accorded with imaging diagnosis in respect of PHT, HCC and diseases of biliary-pancreatic system at the rates of 100%, 97% and 100%, respectively. CONCLUSIONS: Three-dimensional 64-MSCT displays foci of infection and constructions of biliary-pancreatic duct and hepatic conduit stereoscopically.

[Quantitative study of dynamic magnetic resonance perfusion-weighted imaging in rabbit models of implanted hepatic VX2 tumor].

OBJECTIVE: To investigate the possibility of dynamic magnetic resonance (MR) perfusion-weighted imaging (PWI) in rabbit models of implanted hepatic VX2 tumor. METHODS: MRI and PWI images were obtained from 16 rabbit models of implanted hepatic VX2 tumor and 4 normal rabbits at 14, 18, 22, and 26 days after tumor implantation, respectively, and the mean time to enhancement (MTE) and maximum slope of increase (MSI) were estimated and compared with pathological changes. RESULTS: In the rabbit models of implanted hepatic tumor the MTE tended to increase and MSI to descend 14, 18, 22, and 26 days after tumor implantation, showing significant differences from the control group. Coagulation necrosis and fibrous hyperplasia in the tumors appeared to progress with time as found pathologically. CONCLUSION: Dynamic MR PWI quantitative analysis of rabbit models of implanted hepatic VX2 tumor provides valuable means for observing the growth behaviors of VX2 tumor and may be clinically applicable in the evaluation of hepatic diseases.

[Modification of the method for preparing rabbit liver VX2 tumor model and its MRI findings].

OBJECTIVE: To improve the method for preparing rabbit VX2 liver tumor model and observe the magnetic resonance imaging (MRI) features of the implanted tumors. METHODS: Sixteen adult New Zealand white rabbits were assigned randomly into 4 equal groups, and VX2 tumor tissues were implanted into the right and left liver lobes with spiral CT guidance. Plain and contrast-enhanced MR scan and pathological analysis were performed in different stages (14, 18, 22 and 26 days) after tumor implantation. RESULTS: Tumor implantation was successful in all the rabbits, and 18 to 22 days after tumor implantation, the diameters of the tumor ranged from 1 to 2 cm, which allowed observation and study. In plain MR scans, lower or equivalent tumor signal in comparison with hepatic parenchyma was observed, and contrast-enhanced scans produced obvious enhancement of the tumor edges. At 22 days after tumor implantation, obvious necrosis was observed in the center of the tumor. CONCLUSION: This method of preparing rabbit VX2 liver tumor model with spiral CT guidance is simple and convenient, and the tumors can be observed effectively with dynamic plain and contrast-enhanced MR scans.

[Preliminary quantitative study of dynamic magnetic resonance diffusion tensor imaging in rabbit models implanted with hepatic tumor grafts from VX2].

OBJECTIVE: To investigate the feasibility of dynamic magnetic resonance diffusion tensor imaging (DTI) in rabbit models with implanted VX2 hepatic tumor grafts. METHODS: MRI and DTI images were obtained from 16 rabbit models with implanted VX2 hepatic tumor grafts (14, 18, 22, and 26 days after tumor implantation, respectively) and 4 normal rabbits. The average diffusion coefficient (ADC) and exponential ADC (eADC) were estimated and compared against pathological findings. RESULTS: The ADC values increased after tumor implantation but then decreased in the rabbit models, whereas eADC exhibited a pattern of reverse changes. These changes significantly differed from those in the control group. Coagulation necrosis and fibrous hyperplasia showed obvious increase as found by pathological examination. CONCLUSION: Dynamic MR DTI quantitative analysis of rabbit models of implanted VX2 hepatic tumor can partially describe the growth behaviors of implanted liver cancer.

Evaluation of diffusion weighted imaging of magnetic resonance imaging in small focal hepatic lesions: a quantitative study in 56 cases.

BACKGROUND: Diffusion-weighted imaging (DWI) as a new technique of magnetic resonance imaging (MRI) is used to detect focal hepatic lesions. This study was designed to evaluate the significance of DWI to differentiate focal hepatic lesions less than 3 cm in diameter by the quantitation of apparent diffusion coefficient (ADC) values. METHODS: DWI using 1.5T MRI scanner unit was performed with a spin-echo single-shot echo planar imaging (EPI) in 56 cases of small focal hepatic lesions, including hepatocellular carcinoma (11), hepatic metastatic tumor (15), hepatic cavernous hemangioma (14), and hepatic cyst (16). The ADC values of these lesions were calculated respectively. The ratios of the ADC values of lesion/liver in hepatocellular carcinomas and hepatic metastatic tumors were also estimated. RESULTS: The mean ADC values (mm2/s) were (0.93+/-0.06) x 10(-3) in hepatocellular carcinomas, (1.09+/-0.18) x 10(-3) in hepatic metastatic tumors, (1.95+/-0.38) x 10(-3) in hepatic cavernous hemangiomas, and (3.18+/-0.33) x 10(-3) in hepatic cysts. The ratios of ADC values of lesion/liver were 0.90+/-0.06 and 1.15+/-0.14 in hepatocellular carcinoma and hepatic metastatic tumors respectively, which were significantly different (P < 0.05). CONCLUSION: The measurement of ADC values and the ratios of ADC values of lesion/liver are helpful in MR diagnosis and differentiation of focal hepatic lesions.

Quantitative evaluation of diffusion-weighted magnetic resonance imaging of focal hepatic lesions.

AIM: To explore the quantitative analysis of diffusion-weighted magnetic resonance imaging (DWMRI) in differential diagnosis of focal hepatic lesions. METHODS: DWMRI was performed in 149 hepatic lesions, including hepatocellular carcinoma (34 cases), hepatic metastases (37 cases), cavernous hemangioma (42 cases), hepatic cyst (36 cases). Apparent diffusion coefficient (ADC) values were evaluated using four different b values in different sequences. The ratio of ADC values of lesion/liver in hepatocellular carcinoma and hepatic metastases was also calculated. RESULTS: The mean ADC values of hepatic lesions were as follows: hepatocellular carcinoma (0.95+/-0.11)x10(-3) mm2/s, hepatic metastasis (1.13+/-0.21)x10(-3)mm2/s, cavernous hemangioma (1.86+/-0.36)x10(-3) mm2/s, hepatic cyst (3.14+/-0.31)x10(-3) mm2/s. The ratio of ADC values in lesion/liver in hepatocellular carcinoma was 0.91+/-0.11, being significantly different from that in hepatic metastasis (1.21+/-0.18, P<0.05). CONCLUSION: ADC values and quantitative analysis of focal hepatic lesions are of significant values in differential diagnosis of focal hepatic lesions.

[Establishment of canine models of acute mesenteric ischamia].

OBJECTIVE: To establish a new canine model of acute mesenteric ischemia for imaging studies. METHODS: Ten Beagle dogs were divided into ischemic group (n=8) and control group (n=2). Via a 4F Cobra catheter, the absolute ethanol was selectively injected into the superior mesenteric artery (SMA) for embolization in the former group while the saline was injected in the latter. Imaging study and pathological examination were performed. RESULTS: Digital subtraction angiography (DSA) revealed that occlusion of some branches of the SMA was induced in the ischemic group while no changes occurred in the control group. The signs of acute mesenteric ischemia were confirmed by CT and pathological examination in the ischemic group whereas no abnormalities identified in the group. CONCLUSION: Canine models of acute mesenteric ischemia can be established by selective catheterization with absolute ethanol injection.

[Quantitative study of diffusion weighted imaging on magnetic resonance imaging in focal hepatic lesions less than 3 cm].

OBJECTIVE: To evaluate the characteristics of MR imaging of hepatic lesions using measurement of apparent diffusion coefficient (ADC) value of hepatic lesions on diffusion weighted imaging. METHODS: MR diffusion weighted images were obtained in patients with 97 hepatic lesions (22 hepatocellular carcinomas, 21 metastatic tumors, 28 hemangiomas, 26 cysts). ADC values were evaluated with different sequences. The ADC ratio of lesion/liver was estimated. RESULTS: Average ADC values of hepatic lesions were as follows: carcinomas (0.91 +/- 0.07) x 10(-3) mm(2)/s, metastatic tumors (1.13 +/- 0.27) x 10(-3) mm(2)/s, cavernous hemangiomas (1.94 +/- 0.37) x 10(-3) mm(2)/s, cysts (3.26 +/- 0.30) x 10(-3) mm(2)/s. The ADC ratio of lesion/liver was significantly different between primary carcinomas and metastatic tumors (P < 0.05). CONCLUSION: Quantitative study in hepatic lesions using ADC values and the ADC ratio of lesion/liver, would improve the accuracy in diagnosing hepatic lesions.