Paediatric thyroidectomy: When and why? A 25-year institutional experience.

OBJECTIVE: Thyroidectomy in paediatric patients is relatively uncommon. In this study, we reviewed our experience of thyroidectomy in children and identified risk factors associated with postoperative complications. METHODS: We performed a retrospective analysis of paediatric patients who had thyroidectomy in our institution between April 1995 and January 2021. Demographic data, preoperative cytological findings, indications of surgery, surgical complications and histological results were analysed. RESULTS: A total of 87 paediatric patients with 92 thyroidectomy were identified. The indications for surgery were Graves' disease refractory to medical treatments (40.2%), benign thyroid nodules or multinodular goitre (26.4%), thyroid carcinoma (23.0%) and multiple endocrine neoplasm type 2A syndrome (10.3%). Patients presented with thyroid nodules or cervical lymph nodes had a 43.9% risk of malignancy. 66 total thyroidectomy were done with median operation time of 134 min(102-170), while 26 hemi-thyroidectomy were performed (Right side 12/92, Left side 14/92) with median operation time of 65 min(49-102). The median postoperative hospital stay was 2 days(1-4). Intraoperative neck dissection (p = 0.003), drain insertion (p = 0.001) and hypocalcaemia requiring medical treatment (p = 0.004) were associated with longer hospital stay. The median follow-up was 11.3 years (3.0-16.8). 32% patients had immediate postoperative hypocalcaemia and 8% patients had permanent hypoparathyroidism. Transient vocal cord palsy was found in 3 patients(3%) and all resolved within 5-month time upon reassessment direct laryngoscopy. The use of intraoperative recurrent laryngeal nerve monitoring was associated with less vocal cord palsy (p = 0.022). The median disease-free survival was 13.7 years(7.4-17.7) for patients operated for well-differentiated thyroid carcinoma(WDTC). amongst the 9 patients who had prophylactic total thyroidectomy for MEN2A syndrome, 44% were found to have medullary thyroid microcarcinomas on pathology. CONCLUSIONS: Surgical management of paediatric thyroid disease can be complex. Postoperative hypocalcaemia and vocal cord palsy were usually transient after total thyroidectomy. The use of intraoperative recurrent laryngeal nerve monitoring had resulted in less vocal cord palsy. Long-term disease-free survival of patients with thyroid cancer had been achieved with multi-disciplinary management in our centre. LEVEL OF EVIDENCE: Retrospective Comparative Study; Level III.

Orthopaedic Resident Burnout: A Literature Review on Vulnerability, Risk Factors, Consequences and Management Strategies.

Introduction: Orthopaedic surgery is physically demanding. Surgeons may have to work long unpredictable hours especially during residency training. This arduous task comes with the risk of burnout leading to negative repercussions to the surgeon and the patient. In view of strategising peer support, we intend to review the literature and analyse whether orthopaedic resident burnout is a global issue. We also intend to derive common strategies to tackle burnout at individual and organisational levels. Materials and Methods: A literature search was carried out in the databases including PubMed, Scopus, SciELO, and Google Scholar to shortlist studies dealing with orthopaedic residency and related burnout. Those studies that used the Maslach Burnout Inventory (MBI) for quantifying burnout were collectively interpreted. Other studies were reviewed to analyse the vulnerability, risk factors, consequences and management strategies related to burnout. Results: Among a total of 72 titles shortlisted, eight studies independently reported burnout among orthopaedic surgery residents/trainees and used MBI as a tool for assessing burnout. Based on the three subscales of MBI, 37.2% had high degree of emotional exhaustion (EE), 48% had high degree of depersonalisation (DP) and 33.1% perceived low personal accomplishment. This signifies the high prevalence of burnout among orthopaedic residents/trainees. Conclusion: Burnout among orthopaedic surgery residents seems to be a universal problem. Risk factors could be multifactorial, influenced by clinical competency and work-home environment. This can be tackled at the individual level by being aware of burnout syndrome, involving in adequate physical activity and spending quality social time; and at the organisational level by duty hour limitation, professional appreciation and mentorship programme.

Primitive neuroectodermal adrenal gland tumour.

Ewing's sarcoma, also called primitive neuroectodermal tumour of the adrenal gland, is extremely rare. Only a few cases have been reported in the literature. We report on a woman with adult-onset primitive neuroectodermal tumour of the adrenal gland presenting with progressive flank pain. Computed tomography confirmed an adrenal tumour with invasion of the left diaphragm and kidney. Radical surgery was performed and the pain completely resolved; histology confirmed the presence of primitive neuroectodermal tumour, for which she was given chemotherapy. The clinical presentation of this condition is non-specific, and a definitive diagnosis is based on a combination of histology, as well as immunohistochemical and cytogenic analysis. According to the literature, these tumours demonstrate rapid growth and aggressive behaviour but there are no well-established guidelines or treatment strategies. Nevertheless, surgery remains the mainstay of local disease control; curative surgery can be performed in most patients. Adjuvant chemoirradiation has been advocated yet no consensus is available. The prognosis of patients with primitive neuroectodermal tumours remains poor.

Prognostic value of lymph node ratio in stage III colorectal cancer.

AIM: Recent reports show that a positive metastatic to examined lymph nodes ratio (LNR) has prognostic value in malignancies. This study aimed to evaluate the prognostic value of LNR in patients having resection for stage III colorectal cancer. METHOD: From January 2000 to December 2006, patients who underwent resection for stage III colorectal carcinoma were included. All clinicopathological and follow-up data were prospectively collected. The impact of LNR and other clinicopathological factors on survival were evaluated. RESULTS: The study included 533 (52.3% male) patients with a median age of 70 years. The median number of lymph nodes harvested and the median number of positive lymph nodes examined were 11 and 2, respectively. The median LNR was 0.263 (range, 0.03-1). After a median follow up of 52.65 months, the 5-year overall survival and disease-free survival were 55.9% and 49.4%. The patients were stratified into four groups according to LNR quartiles (1, LNR ≤ 0.125; 2, 0.1250.500). The 5-year overall and disease-free survival were 72.8%, 63.1%, 50.0%, 39.6% (P<0.001) and 68.5%, 54.1%, 47.2%, 29.9% (P<0.001), respectively, with increasing LNR groups. On multivariate analysis, age, T stage and LNR were independent predictors of both overall and disease-free survival. Subgroup analysis revealed that the LNR had a prognostic value for disease-free survival irrespective of number of lymph nodes harvested and location of tumour. CONCLUSION: The LNR is an independent prognostic factor for survival in colorectal cancer and is superior to the pN category in TNM staging.

Changes in breast cancer patients after psychosocial intervention as indicated in drawings.

OBJECTIVE: The present study attempts to understand the experience of breast cancer patients who had participated in an Eastern-based body-mind-spirit (BMS) psychosocial intervention program by observing changes in the images made by the patients. METHODS: Pre- and post-intervention drawings on the theme of 'my cancer' were collected from 67 primary breast cancer patients. Two creative art therapists compared the drawings according to the structural and formal art elements (body), the symbols used (mind), and the emotions and feelings presented in the drawings (spirit). Numbers of pre- and post-intervention drawings, showing the presence of each element in these three dimensions, were also counted and compared. RESULTS: There were several changes noted between pre- and post-intervention drawings. The use of color, space, and multiplicity increased from 12 to 17%. Images of breasts decreased from 13 to 0%. Representations of cancer decreased from 15 to 7%. There was a slight increase in symbolic representations of natural, landscapes, and social support in post-drawings (3-6%). The portrayal of negative emotions was greatly reduced from 52 to 3%, while positive emotions increased from 28 to 93% in post-drawings. CONCLUSIONS: The comparison of pre- and post-intervention drawings revealed changes in subject matter and accompanying emotions. Overall, there was a trend in changes toward a more peaceful and hopeful attitude. Through the use of realistic and symbolic images, participants depicted a range of emotions. Limitations and recommendations for using art-making, as an assessment tool and intervention, are addressed.

Sulfatide-tenascin interaction mediates binding to the extracellular matrix and endocytic uptake of liposomes in glioma cells.

Tenascin-C is an extracellular matrix glycoprotein, whose expression is highly restricted in normal adult tissues, but markedly up-regulated in a range of tumors, and therefore serves as a potential receptor for targeted anticancer drug or gene delivery. We describe here a liposomal carrier system in which the targeting ligand is sulfatide. Experiments with tenascin-C-expressing glioma cells demonstrated that binding of liposomes to the extracellular matrix relied essentially on the sulfatide-tenascin-C interaction. Following binding to the extracellular matrix, the sulfatide-containing liposomes were internalized via both caveolae/lipid raft- and clathrin-dependent pathways, which would ensure direct cytoplasmic release of the cargoes carried in the liposomes. Such natural lipid-guided intracellular delivery targeting at the extracellular matrix glycoproteins of tumor cells thus opens a new direction for development of more effective anticancer chemotherapeutics in future.

Lactacystin-induced apoptosis of cultured mouse cortical neurons is associated with accumulation of PTEN in the detergent-resistant membrane fraction.

The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate [PtdIns(3,4,5)P3]. Implicit in this notion is that PTEN needs to be targeted to the plasma membrane to dephosphorylate PtdIns(3,4,5)P3. However, the recruitment of PTEN to the plasma membrane is not fully understood. Here, we demonstrate PTEN accumulation in the detergent-insoluble fraction of neuronal cells in response to treatment by the proteasome inhibitor lactacystin. First, lactacystin induces apoptosis and the activation of caspase-3 in cultured cortical neurons. Second, PTEN undergoes proteolysis to form a truncated 50-kDa form that lacks parts of its C-terminal tail. Third, the truncated PTEN is stably associated with the detergent-insoluble fraction in which the plasma membrane marker protein flotillin-1 resides. Taken together, our results suggest that truncation and accumulation of PTEN to the detergent-insoluble membrane fraction are two events associated with the apoptotic signals of the proteasome inhibitor in cortical neurons.

3D time of flight MR angiography: acquisition with small field of view and low phase encodes.

The aim of the study was to evaluate and compare the image quality of the 3D TOF MRA acquired with a small FOV and low phase encodes with those MR angiographic images acquired with standard pulse sequence parameters. Twenty patients who were referred to our institution for MR imaging of the brain and strictly satisfied the selection criteria were included in this study. Apart from the routine protocol for MR imaging of the brain, 3D TOF MRA of the circle of Willis with a small FOV and a standard FOV were performed. The image quality of all MRA was evaluated by two independent observers who were blind to the pulse sequence parameters. From the standard FOV MRA, 22.5, 12.5, and 5% of the patients were graded as mild, moderate, and severe stenosis of the internal carotid artery, respectively. On the contrary, no apparent stenosis was observed from the small FOV MRA with low phase encodes. Regarding the reduction in MR artifacts and acquisition time achieved with the small FOV 3D TOF MRA with low phase encodes, this might be a useful MR angiographic technique to be used in routine clinical practice.

Digital subtraction in gadolinium-enhanced MR imaging of the brain: a method to reduce contrast dosage.

The aim of the study was to investigate the feasibility of using digital subtraction in contrast-enhanced MR imaging of the brain to reduce the MR contrast dosage without jeopardizing patient care. Fifty-two patients with intracranial lesions, either intra-axial or extra-axial, detected by computerized tomography were selected for contrast-enhanced MR imaging with half-dose and full-dose of gadopentetate dimeglumine. The half-dose unsubtracted, full-dose unsubtracted, and half-dose subtracted MR images were visually assessed by counting the number of enhancing brain lesions in the images and quantitatively analyzed by computing their lesion contrast-to-background ratios (CBR). The visual conspicuity of the half-dose subtracted MR images was comparable to that of the full-dose unsubtracted MR images ( p>0.05), whereas the CBR of the half-dose subtracted images was approximately two to three times higher than that of the full-dose unsubtracted images. The half-dose subtracted T1-weighted spin-echo images might be able to replace the conventional standard-dose T1-weighted spin-echo images in MR imaging of the brain.

Acute vertebral body compression fractures: discrimination between benign and malignant causes using apparent diffusion coefficients.

Diffusion weighted MRI was performed on patients with acute vertebral body compression. The usefulness of the apparent diffusion coefficient (ADC) in differentiating between benign and malignant fractures was evaluated. A total of 49 acute vertebral body compression fractures were found in 32 patients. 25 fractures in 18 patients were due to osteoporosis, 18 fractures in 12 patients were histologically proven to be due to malignancy, and 6 fractures in 2 patients were due to tuberculosis. Signal intensities on T(1) weighted, short tau inversion recovery (STIR) and diffusion weighted images were compared. ADC values of normal and abnormal vertebral bodies were calculated. Except for two patients with sclerotic metastases, benign acute vertebral fractures were hypointense and malignant acute vertebral fractures were hyperintense with respect to normal bone marrow on diffusion weighted images. Mean combined ADCs (ADC(cmb); average of the combined ADCs in the x, y and z diffusion directions) were 0.23 x 10(-3) mm(2) s(-1) in normal vertebrae, 0.82 x 10(-3) mm(2) s(-1) in malignant acute vertebral fractures and 1.94 x 10(-3) mm(2) s(-1) in benign acute vertebral fractures. The differences between ADC(cmb) values were statistically significant (p<0.001). The ADC is useful in differentiating benign from malignant acute vertebral body compression fractures, but there may be overlapping ADC values between malignant fractures and tuberculous spondylitis.

Discrimination of an infected brain tumor from a cerebral abscess by combined MR perfusion and diffusion imaging.

The aim of this study was to investigate the signal characteristics of the abscess wall and tumor wall on diffusion-weighted and perfusion-weighted images and thus to evaluate the feasibility of using combined MR diffusion and perfusion imaging to differentiate pyogenic cerebral abscess from infected brain tumor. The tumor wall of various types of cystic or necrotic brain tumor was significantly hyperintense relative to that of cerebral abscess wall on both diffusion-weighted images and regional cerebral blood volume maps. Sixteen patients who had cerebral masses with large cystic or necrotic cavities were imaged to generate diffusion-weighted images and regional cerebral blood volume maps using single-shot echoplanar imaging (EPI) pulse sequences. Apart from qualitative analysis, apparent diffusion coefficients (ADC) as well as regional cerebral blood volume (rCBV) ratios were calculated from the abscess wall and peripheral tumor wall and comparison was made by using Student's t-test. The tumor wall of various types of cystic or necrotic brain tumor had significantly lower ADCs relative to those of the abscess wall (P<0.005) and thus appeared relatively hyperintense on diffusion-weighted images. The mean rCBV ratio relative to normal white matter (2.90+/-0.62) of the peripheral tumor wall of various types of cystic or necrotic brain tumor were significantly larger than the mean rCBV ratio (0.45+/-0.11) of the pyogenic cerebral abscess wall (P<0.001) by Student's t-test. It is concluded that the combined MR diffusion and perfusion imaging might be capable of differentiating an infected brain tumor from a pyogenic cerebral abscess.

Late temporal lobe necrosis in patients with nasopharyngeal carcinoma: evaluation with combined multi-section diffusion weighted and perfusion weighted MR imaging.

Late temporal lobe necrosis is a well-known and serious complication in patients with nasopharyngeal carcinoma (NPC) following radiotherapy. Owing to the close proximity to the skull base, the medial temporal lobes are inevitably included in the target volume of irradiation. Patients with NPC provide a unique opportunity in study of delay radiation effect in normal human brain. The objective of this study was to evaluate late temporal lobe radiation injury by combined multi-section diffusion weighted and perfusion weighted MR imaging. We prospectively studied 16 patients with typical clinical symptoms of late temporal lobe necrosis or other abnormalities in the temporal lobes incidentally detected by conventional MR imaging. All patients had a previous history of radiotherapy for histologically proven NPC. Conventional T1- and T2-weighted images, fast gradient echo with echo-planar diffusion-weighted and perfusion-weighted MR imaging were performed. Apparent diffusion coefficient (ADC) map and relative cerebral blood volume (rCBV) map were computed via commercially available software. MR diffusion and perfusion images were then analyzed and graded by two independent observers with focusing on the diffusion and perfusion mismatch. The temporal lobe lesions displayed marked high diffusion on the ADC map. The rCBV map also revealed marked hypoperfusion in these temporal lobe lesions in all patients. The areas of abnormality on the rCBV map were significantly larger than the lesions on the ADC map in 14 patients (observer 1) and 13 patients (observer 2). Since late temporal lobe necrosis is probably caused by damage of the endothelium of vessels and ischemia, perfusion and diffusion mismatch might imply injured tissue but potentially salvageable brain tissue. A mismatch may be potentially used to predict the response to treatment in-patients with late temporal lobe necrosis.

Mechanism of clofibrate hepatotoxicity: mitochondrial damage and oxidative stress in hepatocytes.

Peroxisome proliferators have been found to induce hepatocarcinogenesis in rodents, and may cause mitochondrial damage. Consistent with this, clofibrate increased hepatic mitochondrial oxidative DNA and protein damage in mice. The present investigation aimed to study the mechanism by which this might occur by examining the effect of clofibrate on freshly isolated mouse liver mitochondria and a cultured hepatocyte cell line, AML-12. Mitochondrial membrane potential (Delta Psi(m)) was determined by using the fluorescent dye 5,5',6,6'-tetrachloro-1,1', 3,3'-tetraethyl-benzimidazolylcarbocyanine iodide (JC-1) and tetramethylrhodamine methyl ester (TMRM). Application of clofibrate at concentrations greater than 0.3 mM rapidly collapsed the Delta Psi(m) both in liver cells and in isolated mitochondria. The loss of Delta Psi(m) occurred prior to cell death and appeared to involve the mitochondrial permeability transition (MPT), as revealed by calcein fluorescence studies and the protective effect of cyclosporin A (CsA) on the decrease in Delta Psi(m). Levels of reactive oxygen species (ROS) were measured with the fluorescent probes 5-(and-6)-carboxy-2',7'-dichlorofluorescein diacetate (DCFDA) and dihydrorhodamine 123 (DHR123). Treatment of the hepatocytes with clofibrate caused a significant increase in intracellular and mitochondrial ROS. Antioxidants such as vitamin C, deferoxamine, and catalase were able to protect the cells against the clofibrate-induced loss of viability, as was CsA, but to a lesser extent. These results suggest that one action of clofibrate might be to impair mitochondrial function, so stimulating formation of ROS, which eventually contribute to cell death.

MR diffusion-weighted imaging of kidney: differentiation between hydronephrosis and pyonephrosis.

The objective of the study was to evaluate the capability and reliability of the magnetic resonance (MR) diffusion-weighted imaging (DWI) in differentiation between hydronephrosis and pyonephrosis. Single-shot echoplanar MR diffusion-weighted imaging was performed in 12 patients who had dilatation of the renal pelvis and calyces detected by ultrasonography (US). Microbiological tests confirmed that there were four cases of pyonephrosis and eight cases of hydronephrosis. Signal intensities of the collecting (pelvicalyceal) systems on the diffusion-weighted images and apparent diffusion coefficient (ADC) maps were noted. ADC values of the pelvicalyceal system in all patients were computed and compared using Student's t test. On diffusion-weighted images, the pelvicalyceal system of the hydronephrotic kidney was hypointense while the pelvicalyceal system of the pyonephrotic kidney was markedly hyperintense. The mean ADCs of the hydronephrotic and pyonephrotic renal pelvis were 2.98 +/- 0.65 x 10(-3) and 0.64 +/- 0.35 x 10(-3) mm(2)/s, respectively. The extremely low ADC of the renal pelvis of the pyonephrotic kidney accounted for its signal hyperintensity on diffusion-weighted images as well as signal hypointensity on ADC maps. In conclusion, the MR diffusion-weighted imaging may be a reliable tool to differentiate pyonephrosis from hydronephrosis.

EVT endovascular graft for abdominal aortic aneurysm.

BACKGROUND: A variety of prostheses are now available for the endovascular treatment of abdominal aortic aneurysm (AAA). Significant advantages of the EVT device are its unibody design, secure hook attachment system and graft fabric approximating that used in conventional surgery. METHODS: Implantation of the EVT device was attempted in 60 patients who were studied prospectively with an analysis of subsequent problems encountered. RESULTS: Conversion to open repair was required in four cases (6.7%). There were nine tube grafts inserted, 13 aorto-unilateral iliac with crossover grafts and 34 aorto-bi-iliac grafts. There was one death (mortality 1.7%). Endoleaks were identified in eight patients (14%), none of which were proximal; three sealed spontaneously, two were treated with coil embolization, two are being observed and one patient had an iliac attachment converted to an open anastomosis. Access vessel problems were seen in 21 patients (35%); two-thirds were corrected at the time of initial surgery. Seven patients (12%) had primary graft limb problems identified and treated before leaving the operating room. Nine patients (16%) developed secondary graft limb problems, which were diagnosed and treated after the initial surgery. Endovascular treatment was used in eight and was successful in six with surgical revision required in two. On review of these cases to assess if the problem could have been predicted at the time of initial surgery, it was felt that more aggressive treatment of intraoperatively diagnosed graft limb stenoses, even though considered mild, may have prevented 50% of subsequent secondary graft limb occlusions. CONCLUSION: Although the EVT device has significant advantages in the endovascular management of aortic aneurysm, potential graft limb problems need to be actively identified with the majority able to be successfully managed by supplementary endovascular techniques.

Simultaneous estimation of physiological parameters and the input function--in vivo PET data.

Dynamic imaging with positron emission tomography (PET) is widely used for the in vivo measurement of regional cerebral metabolic rate for glucose (rCMRGlc) with [18F]fluorodeoxy-D-glucose (FDG) and is used for the clinical evaluation of neurological disease. However, in addition to the acquisition of dynamic images, continuous arterial blood sampling is the conventional method to obtain the tracer time-activity curve in blood (or plasma) for the numeric estimation of rCMRGlc in mg glucose/100-g tissue/min. The insertion of arterial lines and the subsequent collection and processing of multiple blood samples are impractical for clinical PET studies because it is invasive, has the remote, but real potential for producing limb ischemia, and it exposes personnel to additional radiation and risks associated with handling blood. In this paper, based on our previously proposed method for extracting kinetic parameters from dynamic PET images, we developed a modified version (post-estimation method) to improve the numerical identifiability of the parameter estimates when we deal with data obtained from clinical studies. We applied both methods to dynamic neurologic FDG PET studies in three adults. We found that the input function and parameter estimates obtained with our noninvasive methods agreed well with those estimated from the gold standard method of arterial blood sampling and that rCMRGlc estimates were highly correlated (r = 0.973). More importantly, no significant difference was found between rCMRGlc estimated by our methods and the gold standard method (P > 0.16). We suggest that our proposed noninvasive methods may offer an advance over existing methods.

Modulation of cisplatin cytotoxicity and cisplatin-induced DNA cross-links in HepG2 cells by regulation of glutathione-related mechanisms.

Glutathione (GSH), glutathione S-transferase (GST), and glutathione conjugate export pump (GS-X pump) have been shown to participate collectively in the detoxification of many anticancer drugs, including cisplatin. Identification and regulation of the rate-limiting step in the overall system for cisplatin detoxification is of crucial importance for sensitization of human tumor cells to cisplatin. In this study, the GSH content, GST activity, and GS-X pump activity were regulated separately to examine effects of the regulation on cisplatin cytotoxicity and cisplatin-induced DNA interstrand cross-links (ICL) in HepG2 cells. Seventy-percent depletion of GSH by buthionine sulfoximine (BSO) and 50% increase of GSH by monoethyl GSH ester (GSHe) potentiated and decreased cisplatin cytotoxicity, respectively. This was reflected by a significant decrease and increase of their respective IC(50) values by 62 and 107%. Cisplatin-induced ICL was also potentiated by depletion of GSH by BSO and decreased by enrichment of GSH by GSHe, as shown by a 125% increase and a 34% decrease of cross-linked DNA compared with control samples exposed to cisplatin alone (p = 0.008 and 0.03, respectively). On the other hand, inhibition of GST and GS-X pump by ethacrynic acid, quercetin, tannic acid, and indomethacin at concentrations that inhibited activities of GST and GS-X pump by more than 50% had no significant effects on cisplatin cytotoxicity and cisplatin-induced DNA ICL in these cells. The results showed that of the parameters measured, intracellular GSH seems to be the rate-limiting factor, and its regulation would provide a more promising strategy for sensitization of human liver tumor cells to cisplatin.

Diffusion-weighted MR imaging of the liver: distinguishing hepatic abscess from cystic or necrotic tumor.

BACKGROUND: We evaluated the ability of diffusion-weighted (DW) magnetic resonance (MR) imaging to differentiate between hepatic abscess and cystic or necrotic liver tumor. METHODS: DW MR imaging was performed in 18 patients who had liver masses with large cystic or necrotic cavities detected by computed tomography or ultrasonography. The final diagnoses were pyogenic abscess (five cases), fungal abscess (one), hepatocellular carcinoma (five), cystic metastasis (four), and hepatic cyst (three). Signal intensities on the DW images and apparent diffusion coefficient (ADC) maps were noted. ADCs in all lesions were calculated and compared with Student's t test. RESULTS: All lesions, except hepatic cysts, showed either heterogeneous or homogeneous rim enhancement on postgadolinium images. All abscess cavities showed hyperintensity on DW images and hypointensity on ADC maps. Conversely, the cystic or necrotic portions of all tumors showed hypointensity on DW images and hyperintensity on ADC maps. The mean ADCs (mm(2)/s) were 0.67 +/- 0.35 x 10(-3) in hepatic abscess, 2.65 +/- 0.49 x 10(-3) in cystic or necrotic tumor, 2.93 +/- 0.52 x 10(-3) in hepatic cyst, and 1.98 +/- 0.37 x 10(-3) in normal liver parenchyma. CONCLUSION: DW MR imaging, with the help of ADCs, may be a useful noninvasive imaging technique in differentiating hepatic abscess from cystic or necrotic tumor.