Advances in Ultrasound Tissue Characterization and Its Application in Thermal Ablation of Tumors / 中国医疗器械杂志

The methods of monitoring the thermal ablation of tumor are compared and analyzed in recent years. The principle method results and insufficient of ultrasound elastography and quantitative ultrasound imaging are discussed. The results show that ultrasonic tissue signature has great development space in the field of real-time monitoring of thermal ablation, but there are still some problems such as insufficient monitoring accuracy difficulty in whole-course monitoring and insufficient

Mean scatterer space estimation from ultrasound signals combining singular spectral analysis and entropy

AbstractIntroduction: Ultrasound (US) is a nonionizing radiation capable of real time imaging at low cost. Its most attractive application is quantitative tissue characterization with the objective of differentiating normal tissues from diseased tissues. In this study, an automated method using singular spectrum analysis (SSA) to estimate the mean scatterer space (MSS) of US signals is proposed. Methods Entropy was used to determine the optimal number of components for the SSA. Subsequently, this number was compared with the results using a fixed number of components. A method based on the spectrum of the original signal was also used for comparison. The method was evaluated by using 24,000 simulated US signals, i.e., echoes and jitters backscattered from samples with different ratios of regular-to-irregular structure, as well as with 152 signals obtained from a phantom made of nylon wires. Results For the simulated signals, the proposed method for estimating the MSS presented results similar to the other methods that were tested. However, the magnitude-of-the-spectrum method loses the phase information, and hence, does not allow the characterization of irregular structures. For the signals recorded from the phantom, the methods using SSA and entropy achieved better results. Conclusion In this study, the combination of SSA with entropy to estimate the MSS of a periodic or quasi-periodic medium was proposed. The proposed method achieved similar or better results compared with two other methods found in the scientific literature. The novelty of the proposed method is the application of entropy as a quantitative criterion for selecting the SSA periodic components, allowing it to become independent of heuristic criteria.

Reliability of Ultrasound Tissue Characterization for Quantifing Integrity of Achilles Tendon and Patellar Tendon in People without Tendinopathy / 中国康复理论与实践

@#Objective To investigate the reliability of ultrasound tissue characterization (UTC) for quantifing the integrity of achilles ten-don and patellar tendon in subjects without tendinopathy. Methods From August, 2016 to April, 2017, testers A and B quantified integrity of achilles tendon and patellar tendon of dominant legs from 43 subjects without tendinopathy by UTC in random order respectively. Tester B quantified integrity of patellar tendon of dominant legs from other 22 subjects without tendinopathy by the same way, and repeated the mea-surements the next day. Interclass correlation coefficient (ICC) and the minimum detectable different (MDD) were calculated. Results The ICC of inter-rater reliability of achilles tendon assessment was 0.492 to 0.735, MDD was 0.3%to 3.0%. The ICC of inter-rater reliability of patellar tendon assessment was 0.383 to 0.678, MDD was 0.3%to 4.4%. The ICC of intra-rater reliability of patellar tendon assessment was 0.525~0.760, MDD was 0.6%to 5.3%. Conclusion The test-retest reliability of UTC for the quantification of integrity structure of achilles tendon and patellar tendon is satisfactory with little error, the inter-rater reliability need to be improved. which is a accurate and feasible tool to quantify tendon by the same tester.

Reliability of Ultrasound Tissue Characterization for Quantifing Integrity of Achilles Tendon and Patellar Tendon in People without Tendinopathy / 中国康复理论与实践

@#Objective To investigate the reliability of ultrasound tissue characterization (UTC) for quantifing the integrity of achilles ten-don and patellar tendon in subjects without tendinopathy. Methods From August, 2016 to April, 2017, testers A and B quantified integrity of achilles tendon and patellar tendon of dominant legs from 43 subjects without tendinopathy by UTC in random order respectively. Tester B quantified integrity of patellar tendon of dominant legs from other 22 subjects without tendinopathy by the same way, and repeated the mea-surements the next day. Interclass correlation coefficient (ICC) and the minimum detectable different (MDD) were calculated. Results The ICC of inter-rater reliability of achilles tendon assessment was 0.492 to 0.735, MDD was 0.3%to 3.0%. The ICC of inter-rater reliability of patellar tendon assessment was 0.383 to 0.678, MDD was 0.3%to 4.4%. The ICC of intra-rater reliability of patellar tendon assessment was 0.525~0.760, MDD was 0.6%to 5.3%. Conclusion The test-retest reliability of UTC for the quantification of integrity structure of achilles tendon and patellar tendon is satisfactory with little error, the inter-rater reliability need to be improved. which is a accurate and feasible tool to quantify tendon by the same tester.

Resonancia magnética en el diagnóstico de amiloidosis cardíaca / Magnetic resonance imaging in the diagnosis of cardiac amyloidosis

La resonancia magnética cardíaca (RMC) es un método no invasivo que provee información acerca de la anatomía, función y caracterización tisular del miocardio, llegando a ser de gran utilidad en el diagnóstico y diferenciación de trastornos infiltrativos como la amiloidosis. La amiloidosis cardíaca (AC) es una miocardiopatía restrictiva resultado del depósito de amiloide en el corazón, que determina una semiología característica en la RM que permite establecer el diagnóstico en la mayoría de los casos. Los hallazgos por RMC incluyen hipertrofia miocárdica del ventrículo izquierdo (HVI) con realce tardío positivo en el ventrículo izquierdo (VI) y el resto de las cámaras cardíacas, asociado a alteración en la cinética del gadolinio con anulación del pool sanguíneo y hallazgos adicionales, como derrame pleural o pericárdico o ambos, que apoyan el diagnóstico1-3. Presentamos el caso de una paciente con diagnóstico de amiloidosis sometida a RMC en donde se demuestran los hallazgos característicos de esta patología. (AU)

Cardiac magnetic resonance imaging (MRI) is a noninvasive method of image that provides information about the anatomy, function and tissue characterization, becoming very useful in the diagnosis and differentiation of infiltrative disorders such as amyloidosis. Cardiac amyloidosis (CA) is a restrictive cardiomyopathy result of amyloid deposition in the heart. MRI findings include myocardial hypertrophy with positive late gadolinium enhancement (LGE) in the left ventricle (LV) associated with the altered kinetics of gadolinium and additional findings as pleural and pericardial effusion that support the diagnosis. We report the case of a patient diagnosed with amyloidosis showing the characteristic MR findings in this pathology. (AU)

Predictive efficiency of distinct color image segmentation methods for measuring intramuscular fat in beef / Eficiência preditiva de distintos métodos de segmentação da cor de imagem para mensurar a gordura intramuscular na carne bovina

Intramuscular fat (IMF) influences important quality characteristics of meat, such as flavor, juiciness, palatability, odor and tenderness. Thus, the objective of this study was to apply the following image processing techniques to quantify the IMF in beef: palette; sampling, interval of coordinates; black and white threshold; and discriminant function of colors. Thirty-five samples of beef, with a wide range of IMF, were used. Color images were taken of the meat samples from different muscles, with variability in the IMF content. The IMF of a thin cross-section meat was determined by chemical lipid extraction and was predicted by image analysis. The chemical method was compared with the image analysis. The segmentation procedures were validated by the adjustment of a linear regression equation to the series of values that were observed and predicted, as well as the regression parameters evaluated by the F-test. The predictive power of these approaches was also compared by residual analysis and by the decomposition of the mean square deviations. The results showed that the discriminant function was the best color segmentation method to measure intramuscular fat via digital images, but required adjustments in the prediction pattern.

A gordura intramuscular (GIM) influencia importantes características qualitativas da carne, tais como: sabor, suculência, palatabilidade, odor e maciez. Assim, objetivou-se aplicar diferentes técnicas de processamento de imagem para quantificar a GIM na carne bovina: paleta, amostragem, intervalo de coordenadas, limiar de preto e branco e função discriminante de cores. Foram utilizadas 35 amostras de bifes com uma ampla gama de GIM. Foram capturadas imagens coloridas das amostras de carne de diferentes músculos com uma variabilidade no conteúdo de GIM. A gordura intramuscular da secção transversal e fina de carne foi determinada por extração química dos lipídios e predita por análise de imagem. O método químico foi comparado com a análise de imagem. Os procedimentos de segmentação foram validados pelo ajustamento de uma equação de regressão linear na série de valores observados e preditos e os parâmetros da regressão avaliados pelo teste F. O poder preditivo destas aproximações também foi comparado por meio de análise residual e pela decomposição do quadrado médio dos desvios. Os resultados mostraram que a função discriminante foi o melhor método de segmentação da cor para mensurar a gordura intramuscular via imagem digital, mas necessita de ajustes no padrão de predição.

Ultrasound method applied to characterize healthy femoral diaphysis of Wistar rats in vivo

A simple experimental protocol applying a quantitative ultrasound (QUS) pulse-echo technique was used to measure the acoustic parameters of healthy femoral diaphyses of Wistar rats in vivo. Five quantitative parameters [apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), time slope of apparent backscatter (TSAB), integrated reflection coefficient (IRC), and frequency slope of integrated reflection (FSIR)] were calculated using the echoes from cortical and trabecular bone in the femurs of 14 Wistar rats. Signal acquisition was performed three times in each rat, with the ultrasound signal acquired along the femur's central region from three positions 1 mm apart from each other. The parameters estimated for the three positions were averaged to represent the femur diaphysis. The results showed that AIB, FSAB, TSAB, and IRC values were statistically similar, but the FSIR values from Experiments 1 and 3 were different. Furthermore, Pearson's correlation coefficient showed, in general, strong correlations among the parameters. The proposed protocol and calculated parameters demonstrated the potential to characterize the femur diaphysis of rats in vivo. The results are relevant because rats have a bone structure very similar to humans, and thus are an important step toward preclinical trials and subsequent application of QUS in humans.

In Vitro imaging of MRI and Ultrasound for Colorectal Carcinoma

PURPOSE: To evaluate and compare the accuracy of magnetic resonance imaging (MRI) and ultrasound (US) for detection and estimation of invasion depth of colorectal carcinoma (CRC) by correlation with histopathologic findings in vitro, and to find out the best MR pulse sequence for accurate delineation of tumor from surrounding normal tissue. MATERIALS AND METHODS: Resected specimens of CRC from 45 patients were examined about tumor detectability and invasion depth of US using high frequency (5-17 MHz) linear transducer in a tube filled with normal saline and MRI in a 8-channel quadrate head coil. The institutional review board approved this study and informed consent was waived. MRI with seven pulse sequences of in- and out-of-phases gradient echo T1 weighted images, fast spin echo T2 weighted image and its fat suppression image, fast imaging employing steady-state acquisition (FIESTA) and its fat suppression image, and diffusion weighted image (DWI) were performed. In each case, both imaging findings of MRI and US were evaluated independently for detection and estimation of invasion depth of tumor by consensus of two radiologists and were compared about diagnostic accuracy according to the histopathologic findings as reference standard. Seven MR pulse sequences were evaluated on the point of accurate delineation of tumor from surrounding normal tissue in each specimen. RESULTS: In specimens of CRC, both imaging modalities of MRI (91.1%) and US (86.7%) showed relatively high diagnostic accuracy to detect tumor and evaluate invasion depth of tumor. In early CRC, diagnostic accuracy of US was 87.5% and that of MRI was 75.0%. There was no statistically significant difference between two imaging modalities (p > 0.05). The best pulse sequence among seven MR sequences for accurate delineation of tumor from surrounding normal tissue in each specimen of CRC was fast spin echo T2 weighted image. CONCLUSION: MRI and US show relatively high diagnostic accuracy to detect tumor and evaluate invasion depth of resected specimen of CRC. The most excellent pulse sequence of MRI for accurate delineation of tumor from surrounding normal tissue in CRC is fast spin echo T2 weighted image.

Shear modulus measurement of biological tissues based on Zener model / 医用生物力学

Objective To measure the shear modulus of biological tissues by using Zener model so as to overcome the limitation of Voigt model-based ultrasound vibrometry, and to provide effective approaches of tissue characterization. Methods The mechanical constitutive relation-based shear wave propagation velocity formula was utilized to estimate the shear modulus in terms of the velocities at multiple frequencies via mathematical methods. To obtain shear wave velocities in different objects, experiments were conducted by using different consistencies-based gelatin models and thermally damaged porcine livers as subjects, in which shear waves were induced by ultrasound radio forces. Results Voigt and Zener models were utilized to fit the velocities respectively. The Zener model exhibited higher fitting accuracy than the Voigt model, and the shear modulus could well distinguish gelatin models with different consistencies or porcine livers of different damage degrees. Conclusions The method in this paper provides a potential means of measuring the shear modulus of biological tissues non invasively, which is very promising for tissue characterization and disease diagnosis in medicine.

In Vitro Imaging of MRI and Ultrasound for Gastric Carcinoma

PURPOSE: To evaluate and compare the diagnostic accuracy of MRI and ultrasound(US) for estimation of invasion depth of gastric carcinoma by correlation with histopathologic findings in vitro and to find out the best MR pulse sequence for detection and accurate delineation of tumor. MATERIALS AND METHODS: Resected specimen of total or subtotal gastrectomy from 53 patients with gastric carcinoma were done of imaging studies of MRI and US. And US was examined by using high frequency linear transducer for tumor invasion depth by a radiologist. In each case, both imaging findings of MRI and US were evaluated independently for tumor detection and invasion depth by consensus of two radiologists and were compared the diagnostic accuracy between two imaging modalities according to the histopathologic findings. MR imaging with five MR pulse sequences, spin echo T1 and in- and out-ofphase gradient echo T1 weighted images, FSE and SSFSE T2 weighted images, were performed. Five MR pulse sequences were evaluated and compared on the point of detection and accurate distinction of tumor from surrounding normal tissue. RESULTS: In EGC, diagnostic accuracy of US(77%) was superior than that of MRI(59%) but no statistically significant difference was noted between two imaging modalities(p=0.096). In AGC, both imaging modalities of MRIand US showed relatively high diagnostic accuracy as 97% and 84% respectively. Diagnostic accuracy of MRI was statistically better than that of US at the significant level(p<0.001). The best MR pulse sequence among five in each specimen was FSE T2WI(75.5%, 40/53) in both EGC and AGC. In AGC, FSE T2WI showed excellent imaging quality by showing very high ratio (93.5%, 29/31) of accurate delineation of tumor. CONCLUSION: MRI and US show relatively high diagnostic accuracy in the evaluation of tumor invasion depth of resected specimen in AGC. The most excellent pulse sequence of MRI for the evaluation of tumor invasion depth is FSE T2WI on the point of detection and accurate delineation of tumor in both EGC and AGC.

Nonpalpable Breast Masses: Evaluation by US Elastography

OBJECTIVE: To compare the diagnostic performances of conventional ultrasound (US) and US elastography for the differentiation of nonpalpable breast masses, and to evaluate whether elastography is helpful at reducing the number of benign biopsies, using histological analysis as a reference standard. MATERIALS AND METHODS: Conventional US and real-time elastographic images were obtained for 100 women who had been scheduled for a US-guided core biopsy of 100 nonpalpable breast masses (83 benign, 17 malignant). Two experienced radiologists unaware of the biopsy and clinical findings analyzed conventional US and elastographic images by consensus, and classified lesions based on degree of suspicion regarding the probability of malignancy. Results were evaluated by receiver operating characteristic curve analysis. In addition, the authors investigated whether a subset of lesions was categorized as suspicious by conventional US, but as benign by elastography. RESULTS: Areas under the ROC curves (Az values) were 0.901 for conventional US and 0.916 for elastography (p = 0.808). For BI-RADS category 4a lesions, 44% (22 of 50) had an elasticity score of 1 and all were found to be benign. CONCLUSION: Elastography was found to have a diagnostic performance comparable to that of conventional US for the differentiation of nonpalpable breast masses. The authors conclude that BI-RADS category 4a lesions with an elasticity score of 1 probably do not require biopsy.

In Vitro of MR Imaging of the Resected Normal Gastric Wall: Radiologic-Histologic Correlation

PURPOSE: To evaluate normal human gastric wall layers in vitro using magnetic resonance*(MR) imaging, to correlate the results with the histologic findings, and to determine the optimal technique for evaluation of the gastric wall. MATERIALS AND METHODS: Forty-one normal resected gastric specimens obtained from 25 patients were dissected and placed in a polyethylene tube filled with normal saline. MR imaging with four MR sequences, T1-weighted FLASH*(T1FLASH), fat-saturated T1-weighted FLASH, T2-weighted TSE*(T2TSE), and True-FISP, was performed. The number of gastric wall layers and signal intensity of each layer were determined, and after correlating MR images with the histologic findings, the conspicuity of each layer*(mucosa, submucosa, and muscle), the distinction between each layer, and overall image quality were assessed. RESULTS: The gastric wall was shown by TIFLASH to have two (n=6, 14-6%), three (n=31, 75.6%) and four layers (n=4, 9.8%); by fat-saturated TIFLASH to have two (n=6, 14.6%) and three (n=35, 85.4%) ; by T2TSE to have three (n=24, 58.5%), four (n=11, 26.8%), and five (n=6, 14.6%); and by True-FISP to have one (n=2, 4.9%), two (n=8, 19.5%), three (n=23, 56%), four (n=4, 9.8%), and five (n=4, 9.8%) . The signal intensity of each layer at T1FLASH and fat-saturated T1FLASH was high-intermediate from the lumen in two-layer cases, high-low-high/intermediate in three-layer cases, and high-low-high-intermediate in four-layer cases. The signal intensity of each layer at T2TSE was intermediate/high-low-intermediate in three-layer cases, intermediate low-high-intermediate/low in four-layer cases, and low-high-low-high-low in five-layer cases. Three-layered gastric wall corresponded mostly to mucosa, submucosa, and muscle from the inner to outer layers, respectively. T1FLASH, fat-saturated T1FLASH, and T2TSE were superior to True-FISP in evaluating the gastric wall. T1FLASH and fat-saturated T1FLASH were the best sequences for demonstrating mucosa (p<0.05), and T2TSE was the best for submucosa and the distinction between this and muscle (p<0.05). Both T1FLASH and T2TSE provided the best overall image quality (p<0.05). CONCLUSION: In-vitro MR imaging is an excellent technique for the evaluation of layers of normal gastric wall. T2TSE is the sequence which best demonstrates the conspicuity of submucosa, the distinction between submucosa and muscle, and overall image quality.

Magnetization Transfer Ratio in Head and Neck Lymphadenopathy

PUYPOSE: The purpose of this study was to determine whether the magnetization transfer ratio(MTR) differs between malignant and benign cervical lymphadenopathy. MATERIALS AND METHODS: Magnetization transfer ratios were obtained from 104 lymph nodes of 43 patients. Fifty-five nodes were malignant and 49 were benign. Biopsy or cervical lymph node dissection was performed in 83 nodes, while the remaining 21 were diagnosed clinically or by follow-up imaging studies. Among the 55 malignant nodes, squamous cell carcinomas accounted for 29 cases, lymphomas for 15, undifferentiated carcinomas for four, acute myelogenous leukemia for four, and melanomas for three. The 49 benign nodes comprised 21 cases of reactive hyperplasia, 12 of Kikuchi's disease, nine of acute lymphadenitis, and seven of tuberculous lymphadenitis. All scans were performed using a 1.5T Magnetom Vision(Siemens, Erlangen, Germany) with phased-array or Helmholtz-type neck coil. Scanning was performed with and without magnetization transfer pulse(MT pulse : 11.2 T, 250 Hz band-width, off-set 2.0 KHz) using FLASH 2D sequencing. The region of interest(ROI) for signal intensity(SI) measurements was sampled at the same nodes by keeping the position, shape and size of the ROI constant for the scans before and after the MT pulse was applied. SI measurements were repeated more than three times in each node and the mean value was used to calculate MTR. In this study, however, corrected MTRs(CoMTRs) were used for correction of the effect of background noise produced by magnetic field inhomogeneity. RESULTS: Mean CoMTRs of malignant and benign nodes were 0.33(SD: +/- 0.04) and 0.28(SD: +/- 0.05), respectively. This difference was statistically significant. At CoMTR 0.31, the sensitivity and specificity of malignant nodes were 83% and 75%, respectively. CONCLUSION: A CoMTR of above 0.31 suggests malignant lymphadenopathy. CoMTR is one of the MR criteria which can serve to differentiate between malignant and benign lymphadenopathy.

MR Imaging Findings of Chondroblastic Osteosarcoma

PURPOSE: To evaluate the MR imaging findings of chondroblastic osteosarcoma. MATERIALS AND METHODS: Weincluded 11patients (8 men, 3 women, mean age of 19 years) with pathologically proven chondroblastic osteosarcomaand, as a control group, 20 patients with conventional osteosarcoma. We obtained pre- and post-enhanced MR imagesof all patients and retrospectively reviewed the signal intensity and enhancement pattern of tumors. MR imageswere correlated with histopathology. RESULT: In chondroblastic osteosarcomas, the major portion (< 75%) of thetumor showed low signal intensity on T1-weighted images and homogeneous high signal intensity on T2-weightedimages, but did not show enhancement. The margin of the area showed a lobular pattern. Enhanced nodules (n=11) andstrands (n=8) were seen in the nonenhanced portion. Histopathologically, the nonenhanced portion, nodules, andstrands revealed a chondroid matrix, hypercellular area, and fibrovascular septa, respectively. Conventionalosteosarcomas showed heterogeneous enhancement ; six showed a focal (<25%) nonenhanced area representing necrosis. CONCLUSION: Chondroblastic osteosarcoma showed characteristic MR imaging findings.

Osteosarcoma: Correlation of T1 Map and Histology Map

PURPOSE: To determine whether T1 mapping shows regional differences between viable and necrotic regions of osteosarcomas after anticancer chemotherapy and to assess whether this mapping is able to express the characteristics of various intramural tissue components. MATERIALS AND METHODS: Eleven of 20 osteosarcomas were included in this study, while the remaining nine were excluded because the tumor site was inappropriate for comparison of T1 map and tumor macrosection. All patients underwent MR imaging for the purpose of T1 mapping, followed by pre-operative chemotherapy and subsequentl limb-salvage surgery. Spin echo pulse sequencing was used with varying TR (100, 200, 400, 800, 1600, and 2400 msec) and a constant TE of 20 msec. Using a C-language software program, T1 relaxation time was calculated on a pixel-by-pixel basis and then a T1 map was generated by using a post-processing program, NIH Image. We attempted correlation of the T1 map and histologic findings, particularly in regions of interest(ROI) if certain areas were different from other regions on either the T1 or histologic map. Value was expressed as an average of the ratio of T1 of ROI and T1 of fat tissue, and this was used as an internal reference for normalization of the measurement. RESULTS: Tumor necrosis was 100%(Grade IV) in six specimens, and over 90 % (Grade III) in five. Viable tumor cells were found mostly in regions with chondroid matrix and seldom in regions with osteoid matrix. Regardless of cell viability, values ranged from 0.9 to 9.87(mean, 4.02) in tumor necrotic area with osteoid matrices, and from 3.04 to 3.9(mean, 3.55) in areas with chondroid matrices. Other regions with fibrous tissue proliferation, hemorrhage, and fatty necrosis showed values of 2.92-9.83(mean, 7.20), 2.65 -5.96(mean, 3.59), and 1.43 -3.11(mean, 2.68) respectively. The values of various tissues overlapped. No statistically significant difference was found between regions in which tumors were viable and those with tumor necrosis. CONCLUSION: Although we hypothesized that areas of necrotic tumor would show an increased water component(proton number) and would have a longer T1 value than viable tumor tissues, our results were otherwise. Necrotic osteosarcoma tissves showed a wide range of T1 values according to the prevailing tissue components.

Osteosarcoma after Preoperative Chemotherapy: Tissue Characterization with Specimen MR and the Role of Enhanced MR Imaging

PURPOSE: To evaluate the role of enhanced MR imaging in monitoring tumor response to preoperativechemotherapy for osteosarcomas. MATERIALS AND METHODS: Fo r t y - s even patients (30 males and 17 females, witha mean age 17 years ; range 8 -44 years) with osteosarcomas were included in this study. We obtained spin echoT1-, T2-, and enhanced T1-weighted images before and after pre-operative chemotherapy and in all patientscorrelated changes in MR parameters with histopathologic response. We also obtained 19 specimen MR images,correlating these with histopathologic results in order to estimate tissue specific signals. Patients with morethan 10% viable tumor in the resected specimen were considered poor respon-ders(n=26), while those with 10% orless viable tumor were considered good respon-ders(n=21). RESULTS: Four distinct patterns of signal intensitycorresponded, respectively to dead bone and dense fibrosis (low on T1- and T2-weighted images), viable tumor cells(in-termediate on T1- and high on T2-weighted images), necrosis (low on T1- and high on T 2 - weighted images),and hemorrhage (high on T1- and T2-weighted images), but a wide range of overlap was noted. In all four groups,viable tumor cells remained. Increased tumor vo l u m e, stable or increased edema and enhancement were goodpre-dictors of poor response (predictive values of 83%, 77%, and 89%, respectively). Decreased enhancement was theonly reliable predictor of good response (predictive value, 73%). Changes in tumor margin, homogeneity, signalintensity, and joint effu-sion did not correlate with histopathologic response. CONCLUSION: Signal intensities donot reflect histologic nature. Enhanced MR imaging is a useful predictor of tumor response to preoperativechemotherapy.

Liposarcoma: MR Findings in the Histologic Subtypes

PURPOSE: To evaluate the MR imaging findings of liposarcomas of different histologic subtypes. MATERIALS AND METHODS: We evaluated MR images of 21 patients (5 men and 16 women, mean age, 55 years) with liposarcoma andcorrelated the findings with the results of histopathology. In the study group seven liposarcomas werewell-differentiated, seven were myxoid, three were mixed, two were pleomorphic, and one was round cell. RESULTS: On T1 -and T2 - weighted images, six of seven well-differentiated liposarcomas showed signal intensity equal tothe fat and hypointense septa, while the other showed low signal intensity on a T1 -weighted image, heterogeneoushigh signal intensity on a T2- weighted image, heterogeneous enhancement after the administration of contrastmedia and was dedifferentiate. Nine masses in seven patients with myxoid liposarcoma showed low signal intensityon T1-weighted images, six of the nine showed lace-like foci of high signal intensity. On T2 -weighted images, allmasses showed homogeneous high signal intensity. After administration of contrast media, five of seven massesshowed heterogeneous enhancement. Two of three mixed form were well-differentiated and myxoid types, and twosubtypes were separable on MR. Pleomorphic, round cell, mixed type myxoid and pleomorphic and unclassified casesshowed low signal intensity on T1-weighted images, heterogeneous high signal intensity on T2-weighted andheterogeneous enhancement. CONCLUSION: Using MR imaging, well-differentiated and myxoid liposcarcomas may bedifferentiated from other types.

MR Imaging of Focal Hepatic Masses: Comparison between Half-Fourier Acquisition Single-shot TSE(HASTE) andSingle-shot Echo Planar Imaging

PURPOSE: We undertook this study to evaluate breath-hold Half-Fourier Acquisition Single-shot TSE(HASTE) andsingle-shot echo planar MR imaging for the detection of focal hepatic masses. MATERIALS AND METHODS: Using a 1.5Tsuperconductive system, HASTE, vascular dephasing inversion recovery spin echo EP(VDIR-SE-EP), inversion recoveryspin echo EP(IR-SE-EP), and free induction decay EP(FID-EP) were performed in 31 patients with 34 focal livermasses. Images were compared on the basis of detection sensitivity of focal hepatic masses, liver signal-to-noiseratio(S/N), lesion-to-liver contrast-to-noise ratio(C/N), and image quality. Images analysis was performed by tworadiologists, who reached a consensus. RESULT: The detection sensitivity of focal hepatic masses with HASTE was94.1%, with VDIR-SE-EP and IR-SE-EP, this was 91.2%, and with FID-EP, the figure was 88.2%. Liver S/Ns werehighest on HASTE images, which were significantly better(p<.05) than the three types of EP image. Overalllesion-to-liver C/Ns were highest on VDIR-SE-EP and IR-SE-EP(p<.05). Lesion-to-liver C/Ns were highest onVDIR-SE-EP and IR-SE-EP for solid lesions, but for non-solid lesions, were highest on HASTE (p<.05). Compared withHASTE images, EP images were poor. CONCLUSION: For the detection of focal hepatic masses, the sensitivity ofVDIR-SE-EP and IR-SE-EP was similar to that of HASTE. When using the former, acquisition time was substantiallyreduced but image quality was poor.

Sequential Changes of Fresh and Fixed Specimen on MRI: Optimal Time Interval and Fixatives for Good Correlation with in Vivo State

PURPOSE: With the development of MR Imaging techniques, MRI and MR spectroseopy can be used to evaluatespecimens both in vivo and in vitro. For extracted tissue specimens we wished to obtain MR images which correlatedwell with images obtained in vive; the purpose of this study was to determine which fixatives and time intervalbest facilitated this objective. MATERIALS AND METHODS: After in vivo MR imaging, sample tissues of liver, renalcortex and renal medulla were obtained from ten healthy rabbits. Each tissue sample was placed in 75% ethanol, 10%formalin, and 0.9% normal saline and MR scans of each sample were performed at 30 minutes, 11/2, 3, 6, and 12hours after resection. Signal intensities of the images were measured and their sequential changes were evaluated. RESULTS: On T1WI, signal intensities of both tissue specimens fixed in formalin and ethanol and untreatedspecimens increased significantly during the first 30 minutes. The increased signal intensity then seen for 12hours was greater than on T2WI. On T2WI, signal ntensities of tissue specimens fixed in formalin and ethanol anduntreated specimens showed no significant changes within the first 30 minutes; after that, they showed less signalintensity change for 12 hours than on T1WI. CONCLUSION: To obtain MR images with the same signal intensities as invivo tissue, MRI of tissue specimens in the untreated state should be performed as soon as possible afterresection. On T2WI, signal intensities of tissue specimens were more similar to in vivo tissue than on T1WI.

MR Imaging Findings of Synovial Sarcoma: Emphasis on Signal

PURPOSE: To determine the MR imaging findings of synovial sarcoma, with emphasis on the signal characteristicsof pathologically correlated T2-weighted images. MATERIALS AND METHODS: MR images of 14 cases ofpathologically-proven synovial sarcomas were retrospectively reviewed and correlated with the histopathologicfindings. We analyzed the signal intensity of T1- and T2-weighted images and the incidence of triple signalintensity, and evaluated the frequency of fluid-fluid levels, internal fibrous septa, calcification, the invasionof bone or neurovascular bundles and the involvement of joint capsules, as well as the size, location and marginof the tumors and pattern of contrast enhancement. RESULTS: Necrosis, cystic change or hemorrhage was suggested in11 cases, ten of which showed triple signal intensity, and in all cases, was pathologically confirmed. Fluid-fluidlevels were found in three cases and internal septa in ten. In four cases, maximum diameter was less than 5cm, andin nine, was greater than this. No mass was detected in one case. The tumor was located in the low extremity(n=9),pelvic girdle and hip joint area(n=2), scapular(n=1), shoulder joint area(n=1), and scalp(n=1). Eleven casesshowed a relatively well-defined margin and nine showed lobulation. Except in the area of necrosis and cysticchange, the pattern of contrast enhancement was diffuse and inhomogenous. Bony invasion was detected in two cases,neurovascular encasement in four, calcification in four, and joint capsule invasion in four. CONCLUSION: OnT2-weighted images, synovial sarcoma frequently showed triple signal intensity and internal septa with fluid-fluidlevels ; this was induced by cystic changes due to necrosis and hemorrhage.