A review of antenna designs for percutaneous microwave ablation

Microwave (MW) antenna is a key element in microwave ablation (MWA) treatments as the means that energy is delivered in a focused manner to the tumor and its surrounding area. The energy delivered results in a rise in temperature to a lethal level, resulting in cell death in the ablation zone. The delivery of energy and hence the success of MWA is closely dependent on the structure of the antennas. Therefore, three design criteria, such as expected ablation zone pattern, efficiency of energy delivery, and minimization of the diameter of the antennas have been the focus along the evolution of the MW antenna. To further improve the performance of MWA in the treatment of various tumors through inventing novel antennas, this article reviews the state-of-the-art and summarizes the development of MW antenna designs regarding the three design criteria.     

Spatial and Temporal Control of Hyperthermia Using Real Time Ultrasonic Thermal Strain Imaging with Motion Compensation,Phantom Study

Mild hyperthermia has been successfully employed to induce reversible physiological changes that can directly treat cancer and enhance local drug delivery. In this approach, temperature monitoring is essential to avoid undesirable biological effects that result from thermal damage. For thermal therapies, Magnetic Resonance Imaging (MRI) has been employed to control real-time Focused Ultrasound (FUS) therapies. However, combined ultrasound imaging and therapy systems offer the benefits of simple, low-cost devices that can be broadly applied. To facilitate such technology, ultrasound thermometry has potential to reliably monitor temperature. Control of mild hyperthermia was previously achieved using a proportional-integral-derivative (PID) controller based on thermocouple measurements. Despite accurate temporal control of heating, this method is limited by the single position at which the temperature is measured. Ultrasound thermometry techniques based on exploiting the thermal dependence of acoustic parameters (such as longitudinal velocity) can be extended to create thermal maps and allow an accurate monitoring of temperature with good spatial resolution. However, in vivo applications of this technique have not been fully developed due to the high sensitivity to tissue motion. Here, we propose a motion compensation method based on the acquisition of multiple reference frames prior to treatment. The technique was tested in the presence of 2-D and 3-D physiological-scale motion and was found to provide effective real-time temperature monitoring. PID control of mild hyperthermia in presence of motion was then tested with ultrasound thermometry as feedback and temperature was maintained within 0.3°C of the requested value.     

Interpolated Compressed Sensing for 2D Multiple Slice Fast MR Imaging

Sparse MRI has been introduced to reduce the acquisition time and raw data size by undersampling the k-space data. However, the image quality, particularly the contrast to noise ratio (CNR), decreases with the undersampling rate. In this work, we proposed an interpolated Compressed Sensing (iCS) method to further enhance the imaging speed or reduce data size without significant sacrifice of image quality and CNR for multi-slice two-dimensional sparse MR imaging in humans. This method utilizes the k-space data of the neighboring slice in the multi-slice acquisition. The missing k-space data of a highly undersampled slice are estimated by using the raw data of its neighboring slice multiplied by a weighting function generated from low resolution full k-space reference images. In-vivo MR imaging in human feet has been used to investigate the feasibility and the performance of the proposed iCS method. The results show that by using the proposed iCS reconstruction method, the average image error can be reduced and the average CNR can be improved, compared with the conventional sparse MRI reconstruction at the same undersampling rate.     

Microwave ablation combining surgery for the treatment of multiorgan cystic echinococcosis: A case report

Cystic echinococcosis (CE) is a global public health problem associated with a high overall disease burden. Multiple organ systems are involved in approximately 20% of cases, and treatment is challenging and rarely reported. In this study, we described microwave ablation (MWA) combining surgery for the treatment of a multiorgan CE patient. The patient underwent percutaneous MWA for a hepatic CE3b lesion and exploratory resection of the pelvic cavity lesions. The hepatic lesion was effectively treated by MWA, and invasiveness was reduced by avoiding hepatectomy. The patient had a favorable prognosis at a 20-month's follow-up. More studies are needed to evaluate its usefulness in CE treatment.     

Non-Invasive Targeted Peripheral Nerve Ablation Using 3D MR Neurography and MRI-Guided High-Intensity Focused Ultrasound (MR-HIFU): Pilot Study in a Swine Model

Purpose

Ultrasound (US)-guided high intensity focused ultrasound (HIFU) has been proposed for noninvasive treatment of neuropathic pain and has been investigated in in-vivo studies. However, ultrasound has important limitations regarding treatment guidance and temperature monitoring. Magnetic resonance (MR)-imaging guidance may overcome these limitations and MR-guided HIFU (MR-HIFU) has been used successfully for other clinical indications. The primary purpose of this study was to evaluate the feasibility of utilizing 3D MR neurography to identify and guide ablation of peripheral nerves using a clinical MR-HIFU system.

Methods

Volumetric MR-HIFU was used to induce lesions in the peripheral nerves of the lower limbs in three pigs. Diffusion-prep MR neurography and T1-weighted images were utilized to identify the target, plan treatment and immediate post-treatment evaluation. For each treatment, one 8 or 12 mm diameter treatment cell was used (sonication duration 20 s and 36 s, power 160–300 W). Peripheral nerves were extracted < 3 hours after treatment. Ablation dimensions were calculated from thermal maps, post-contrast MRI and macroscopy. Histological analysis included standard H&E staining, Masson’s trichrome and toluidine blue staining.

Results

All targeted peripheral nerves were identifiable on MR neurography and T1-weighted images and could be accurately ablated with a single exposure of focused ultrasound, with peak temperatures of 60.3 to 85.7°C. The lesion dimensions as measured on MR neurography were similar to the lesion dimensions as measured on CE-T1, thermal dose maps, and macroscopy. Histology indicated major hyperacute peripheral nerve damage, mostly confined to the location targeted for ablation.

Conclusion

Our preliminary results indicate that targeted peripheral nerve ablation is feasible with MR-HIFU. Diffusion-prep 3D MR neurography has potential for guiding therapy procedures where either nerve targeting or avoidance is desired, and may also have potential for post-treatment verification of thermal lesions without contrast injection.     

Identification of controlled-complexity thermal therapy models derived from magnetic resonance thermometry images

Medical imaging provides information valuable in diagnosis, planning, and control of therapies. In this paper, we develop a method that uses a specific type of imaging--the magnetic resonance thermometry--to identify accurate and computationally efficient site and patient-specific computer models for thermal therapies, such as focused ultrasound surgery, hyperthermia, and thermally triggered targeted drug delivery. The developed method uses a sequence of acquired MR thermometry images to identify a treatment model describing the deposition and dissipation of thermal energy in tissues. The proper orthogonal decomposition of thermal images is first used to identify a set of empirical eigenfunctions, which captures spatial correlations in the thermal response of tissues. Using the reduced subset of eigenfunction as a functional basis, low-dimensional thermal response and the ultrasound specific absorption rate models are then identified. Once identified, the treatment models can be used to plan, optimize, and control the treatment. The developed approach is validated experimentally using the results of MR thermal imaging of a tissue phantom during focused ultrasound sonication. The validation demonstrates that our approach produces accurate low-dimensional treatment models and provides a convenient tool for balancing the accuracy of model predictions and the computational complexity of the treatment models.     

Estimation of leaf water potential by thermal imagery and spatial analysis

Canopy temperature has long been recognized as an indicator of plant water status and as a potential tool for irrigation scheduling. In the present study, the potential of using thermal images for an in-field estimation of the water status of cotton under a range of irrigation regimes was investigated. Thermal images were taken with a radiometric infrared video camera. Specific leaves that appeared in the camera field of view were sampled, their LWP was measured and their temperature was calculated from the images. Regression models were built in order to predict LWP according to the crop canopy temperature and to the empirical formulation of the crop water stress index (CWSI). Statistical analysis revealed that the relationship between CWSI and LWP was more stable and had slightly higher correlation coefficients than that between canopy temperature and LWP. The regression models of LWP against CWSI and against leaf temperatures were used to create LWP maps. The classified LWP maps showed that there was spatial variability in each treatment, some of which may be attributed to the difference between sunlit and shaded leaves. The distribution of LWP in the maps showed that irrigation treatments were better distinguished from each other when the maps were calculated from CWSI than from leaf temperature alone. Furthermore, the inclusion of the spatial pattern in the classification enhanced the differences between the treatments and was better matched to irrigation amounts. Optimal determination of the water status from thermal images should be based on an overall view of the physical status as well as on the analysis of the spatial structure. Future study will involve investigating the robustness of the models and the potential of using water status maps, derived from aerial thermal images, for irrigation scheduling and variable management in commercial fields.     

Accuracy of real-time MR temperature mapping in the brain: A comparison of fast sequences

PurposeTo compare magnetic resonance (MR) thermometry based on the proton resonance frequency (PRF) method using a single shot echoplanar imaging (ss EPI) sequence to both of the standard sequences, gradient echo (GRE) and segmented echoplanar imaging (seg EPI) in the in vivo human brain, at 1.5T and 3T.Material and methodsRepetitive MR thermometry was performed on the brain of six volunteers using GRE, seg EPI, and ss EPI sequences on whole-body 1.5T and 3T clinical systems using comparable acquisition parameters. Phase stability and temperature data precision in the human head were determined over 12 min for the three sequences at both field strengths. An ex-vivo swine skeletal muscle model was used to evaluate temperature accuracy of the ss EPI sequence during heating by high intensity focused ultrasound (HIFU).ResultsIn-vivo examinations of brain revealed an average temperature precision of 0.37 °C/0.39 °C/0.16 °C at 3T for the GRE/seg EPI/ss EPI sequences. At 1.5T, a precision of 0.58 °C/0.63 °C/0.21 °C was achieved. In the ex-vivo swine model, a strong correlation of temperature data derived using ss EPI and GRE sequences was found with a temperature deviation <1 °C.ConclusionThe ss EPI sequence was the fastest and the most precise sequence for MR thermometry, with significantly higher accuracy compared to GRE.     

Magnetic Resonance Imaging Assessment of Effective Ablated Volume following High Intensity Focused Ultrasound

Under magnetic resonance (MR) guidance, high intensity focused ultrasound (HIFU) is capable of precise and accurate delivery of thermal dose to tissues. Given the excellent soft tissue imaging capabilities of MRI, but the lack of data on the correlation of MRI findings to histology following HIFU, we sought to examine tumor response to HIFU ablation to determine whether there was a correlation between histological findings and common MR imaging protocols in the assessment of the extent of thermal damage. Female FVB mice (n = 34), bearing bilateral neu deletion tumors, were unilaterally insonated under MR guidance, with the contralateral tumor as a control. Between one and five spots (focal size 0.5 × 0.5 × 2.5 mm³) were insonated per tumor with each spot receiving approximately 74.2 J of acoustic energy over a period of 7 seconds. Animals were then imaged on a 7T MR scanner with several protocols. T1 weighted images (with and without gadolinium contrast) were collected in addition to a series of T2 weighted and diffusion weighted images (for later reconstruction into T2 and apparent diffusion coefficient maps), immediately following ablation and at 6, 24, and 48 hours post treatment. Animals were sacrificed at each time point and both insonated/treated and contralateral tumors removed and stained for NADH-diaphorase, caspase 3, or with hematoxylin and eosin (H&E). We found the area of non-enhancement on contrast enhanced T1 weighted imaging immediately post ablation correlated with the region of tissue receiving a thermal dose CEM43 ≥ 240 min. Moreover, while both tumor T2 and apparent diffusion coefficient values changed from pre-ablation values, contrast enhanced T1 weighted images appeared to be more senstive to changes in tissue viability following HIFU ablation.     

Magnetic resonance thermometry at 7T for real-time monitoring and correction of ultrasound induced mild hyperthermia

While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (≥7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition. An MRgFUS system capable of delivering a controlled 3D acoustic dose during real time MRT with proportional, integral, and derivative (PID) feedback control was developed and validated. Real-time MRT was validated in a tofu phantom with fluoroptic temperature measurements, and acoustic heating simulations were in good agreement with MR temperature maps. In an in vivo Met-1 mouse tumor, the real-time PID feedback control is capable of maintaining the desired temperature with high accuracy. We found that real time MR control of hyperthermia is feasible at high field, and k-space based PPI techniques may be implemented for increasing temporal resolution while maintaining temperature accuracy on the order of 1°C.     

超声造影引导下行微波消融术治疗肝癌的临床效果分析*

摘要目的：评估超声造影(CEUS)引导下微波消融(MWA)治疗肝癌的有效性及应用价值。方法：108 例肝癌患者,共147个病灶经 MWA治疗。根据患者在做常规超声检查时,是否有扫查不清晰的结节或其他影像学检查提示可能存在多发结节等,分成CEUS 族和对照组。CEUS组41 名患者,年龄(57.9± 7.8）岁,共57 个病灶,平均直径（2.4± 1.5）cm,经超声造影引导下行微波消融治疗。 对照组67 名患者,年龄（55.5± 8.9）岁,共90 个病灶,平均直径（2.6± 1.7）cm,常规超声引导下同种条件行微波消融治疗。治疗后 对两组患者进行6～12 个月随访。结果：CEUS组的57 个病灶均清晰显示其位置、数目、大小、边界、形态,完全消融的结节为55 个,未完全消融的结节为2个。对照组67 名患者的90 个病灶,完全消融的病灶78 个;未完全消融的结节12 个。CEUS组完全消 融率高于病例对照组(96.49 %VS 86.67 %;P< 0.05）。随访6～12 个月后发现,CEUS 组完全消融率高于病例对照组(P< 0.05）,差 异有统计学意义。结论：CEUS能更好的显示病灶的位置、数目、大小,更精确显示病灶边界、范围,造影引导下MWA 是一种有效 提高完全消融效率的方法,具有较大应用价值。     

超声造影引导下行微波消融术治疗肝癌的临床效果分析

目的：评估超声造影（CEUS）gl导下微波消融（MwA）治疗肝癌的有效性及应用价值。方法：108例肝癌患者,共147个病灶经MWA治疗。根据患者在做常规超声检查时,是否有扫查不清晰的结节或其他影像学检查提示可能存在多发结节等,分成CEUS族和对照组。CEUS组41名患者,年龄（57．9±7．8）岁,共57个病灶,平均直径（2．4±1．5）cm,经超声造影引导下行微波消融治疗。对照组67名患者,年龄（55．5±8．9）岁,共90个病灶,平均直径（2．6±1．7）cm,常规超声引导下同种条件行微波消融治疗。治疗后对两组患者进行6～12个月随访。结果：CEUS组的57个病灶均清晰显示其位置、数目、大小、边界、形态,完全消融的结节为55个,未完全消融的结节为2个。对照组67名患者的90个病灶,完全消融的病灶78个;未完全消融的结节12个。CEUS组完全消融率高于病例对照组（96．49％VS86．67％;P〈0．05）。随访6～12个月后发现,CEUS组完全消融率高于病例对照组（P〈0．05）,差异有统计学意义。结论：CEUS能更好的显示病灶的位置、数目、大小,更精确显示病灶边界、范围,造影引导下MWA是一种有效提高完全消融效率的方法,具有较大应用价值。     

Investigation of the Saturation Pulse Artifact in Non-Enhanced MR Angiography of the Lower Extremity Arteries at 7 Tesla

When performing non-enhanced time-of-flight MR angiography of the lower extremity arteries at 7 T with cardiac triggering, the acquisition time is a crucial consideration. Therefore, in previous studies, saturation RF pulses were applied only every second TR. In the axial source images a slight artifact with an appearance similar to aliasing could be observed. The purpose of this study was to investigate the origin of this artifact. The reason for the artifact is supposed to be related to the two effective TRs during acquisition caused by the sparsely applied saturation RF pulse. Several sequence variants were simulated and implemented within the sequence source code to examine this hypothesis. An adaptation of the excitation flip angles for each TR as well as a correction factor for the k-space data was calculated. Additionally, a different ordering of the k-space data during acquisition was implemented as well as the combination of the latter with the k-space correction factor. The observations from the simulations were verified using both a static and a flow phantom and, finally, in a healthy volunteer using the same measurement setup as in previous volunteer and patient studies. Of all implemented techniques, only the reordering of the k-space was capable of suppressing the artifact almost completely at the cost of creating a ringing artifact. The phantom measurements showed the same results as the simulations and could thus confirm the hypothesis regarding the origin of the artifact. This was additionally verified in the healthy volunteer. The origin of the artifact could be confirmed to be the periodic signal variation caused by two effective TRs during acquisition.     

Influence of Several Sources and Amounts of Iron on DNA, Lipid and Protein Oxidative Damage During Anaemia Recovery

Nanoparticles (NPs) in agricultural systems can potentially be used as appropriate candidate for change in growth, development, productivity, and quality of plants. In the present study, we assessed the effect of TiO₂ NP concentrations (0, 2, 5, and 10 ppm) on changes of membrane damage indexes like electrolyte leakage index (ELI) and malondialdehyde (MDA) during cold stress (CS) 4 °C in sensitive (ILC 533) and tolerant (Sel 11439) chickpea (Cicer arietinum L.) genotypes. Aggregation of NPs within the vacuole and chloroplast indicated absorbed NPs in seedlings. Bioaccumulation of NPs showed that, under thermal treatments, the sensitive genotype had more permeability to NPs compared to the tolerant one, and TiO₂ content was higher during CS compared to optimum temperature. Physiological indexes were positively affected by NP treatments during thermal treatments. TiO₂ NP treatments (especially 5 ppm) caused a decrease in ELI during thermal treatments, whereas ELI content under CS treatment increased at 0 ppm TiO₂ in both genotypes. Under thermal treatments, although the genotype 11439 showed lower accumulation of MDA than ILC 533 genotype, a significant decrease was observed in MDA content at 5 ppm TiO₂. Results showed that TiO₂ treatments not only did not induce oxidative damage in sensitive and tolerant chickpea genotypes but also alleviated membrane damage indexes under CS treatment. It was suggested for the first time that TiO₂ NPs improved redox status of the genotypes under thermal treatments. New findings possibly would reveal the use of NPs generally or TiO₂ NPs especially for increase of cold tolerance in crops.     

Antenna design for microwave hepatic ablation using an axisymmetric electromagnetic model

Background  

An axisymmetric finite element method (FEM) model was employed to demonstrate important techniques used in the design of antennas for hepatic microwave ablation (MWA). To effectively treat deep-seated hepatic tumors, these antennas should produce a highly localized specific absorption rate (SAR) pattern and be efficient radiators at approved generator frequencies.     

Method for Simultaneous fMRI/EEG Data Collection during a Focused Attention Suggestion for Differential Thermal Sensation

In the present work, we demonstrate a method for concurrent collection of EEG/fMRI data. In our setup, EEG data are collected using a high-density 256-channel sensor net. The EEG amplifier itself is contained in a field isolation containment system (FICS), and MRI clock signals are synchronized with EEG data collection for subsequent MR artifact characterization and removal. We demonstrate this method first for resting state data collection. Thereafter, we demonstrate a protocol for EEG/fMRI data recording, while subjects listen to a tape asking them to visualize that their left hand is immersed in a cold-water bath and referred to, here, as the cold glove paradigm. Thermal differentials between each hand are measured throughout EEG/fMRI data collection using an MR compatible temperature sensor that we developed for this purpose. We collect cold glove EEG/fMRI data along with simultaneous differential hand temperature measurements both before and after hypnotic induction. Between pre and post sessions, single modality EEG data are collected during the hypnotic induction and depth assessment process. Our representative results demonstrate that significant changes in the EEG power spectrum can be measured during hypnotic induction, and that hand temperature changes during the cold glove paradigm can be detected rapidly using our MR compatible differential thermometry device.     

Detailing Radio Frequency Heating Induced by Coronary Stents: A 7.0 Tesla Magnetic Resonance Study

The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR) holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF) power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF) simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR) limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study.     

二陈汤加减联合微波消融术对晚期非小细胞肺癌患者Th17/Treg失衡和血管生成因子的影响

摘要 目的：探讨二陈汤加减联合微波消融术（MWA）对晚期非小细胞肺癌（NSCLC）患者辅助性T细胞17（Th17）/调节性T细胞（Treg）失衡和血管生成因子的影响。方法：选择2020年9月~2022年9月期间我院收治的120例不可或不愿手术切除或体部立体定向放疗的ⅢB-Ⅳ期并同意MWA治疗的NSCLC患者。采用随机对照的方法将所有患者分为观察组（二陈汤加减联合MWA治疗,60例）及对照组（MWA治疗,60例）。对比两组中医主要证候总评分、EORTC生命质量测定量表（EORTC QLQ-C30）评分、Th17/Treg失衡、血清肿瘤标志物、血管生成因子和不良反应发生率。结果：治疗后,观察组中医主要证候总评分、EORTC QLQ- C30评分低于对照组（P<0.05）。治疗后,观察组Th17细胞比例、Treg细胞比例低于对照组,Th17/Treg比值高于对照组（P<0.05）。治疗后,观察组癌胚抗原（CEA）、鳞状细胞癌相关抗原（SCC-Ag）和角化素蛋白片段19（Cyfra21-1）低于对照组（P<0.05）。治疗后,观察组血管内皮生长因子（VEGF）和碱性成纤维细胞生长因子（bFGF）低于对照组（P<0.05）。两组不良反应发生率组间对比未见差异（P>0.05）。结论：二陈汤加减联合MWA对晚期NSCLC患者,可有效降低血清肿瘤标志物水平,促进临床症状改善,调节Th17/Treg比例失衡和血管生成因子。     

Ontogenetic stage-dependent effect of temperature on developmental and metabolic rates in a holometabolous insect

Different hypotheses attempt to explain how different stages of organisms with complex life cycles respond to environmental changes. Most studies have focused at the among-species level showing similar responses to temperature throughout ontogeny. However, there is no agreement about the pattern expected at the intraspecific scale where a strong selective effect is expected. In this paper, we studied the effects of thermal treatments on a life history trait (developmental rate) and a physiological trait (metabolic rate) during development in the fruitfly Drosophila buzzatii. First, we estimated the rate of development during larval life (LDR) and the pupal stage (PDR) in flies derived from two natural populations exposed to several thermal treatments. Our results showed that the developmental rate ratio, LDR/PDR, did not vary between populations, and that the effects of thermal treatments were stage specific. Second, we studied the relationship between developmental rate (DR) and metabolic rate (MR) in each life cycle stage. We found that allometric relationships between DR and MR varied throughout ontogeny, a pattern that shed light on the mechanisms responsible for thermal plasticity. We conclude that, although different populations may show developmental rate isomorphy; larvae and pupae may choose alternative “decisions” in terms of life-history evolution and physiological traits when confronted to different thermal environments.     

In vivo assessment of microcystin-LR-induced hepatotoxicity in the rat using proton nuclear magnetic resonance (1H-NMR) imaging.

Microcystin-LR (MCLR)-induced hepatotoxicity was assessed in vivo in male Sprague-Dawley rats (150-350 g) using magnetic resonance imaging (MRI). Following the intraperitoneal administration of MCLR (LD(50)), a region of damage, characterised by increased signal intensity on T(2)-weighted images, was seen proximal to the hepatic portal vein in the liver. Similarly, increased signal intensity was seen in the chemical-shift selective images (CSSI) of water frequency, proximal to the hepatic portal vein in the liver. This indicates that the increased signal intensity observed in the T(2)-weighted images was due to an increased amount of magnetic resonance (MR) visible protons in the tissue which represents an oedematous response. Image analysis of regions of apparent damage around the hepatic portal vein indicated a statistically significant increase in signal intensity in this region. Mitochondrial swelling and lipid inclusions were observed by transmission electron microscopy (TEM) in samples obtained from the oedematous regions of the liver using spatial coordinates from the magnetic resonance (MR) images. Massive haemorrhagic necrosis and nuclear swelling were observed by light microscopy in the centrilobular regions of the lobules.