Biomedical subjects

Thomas M Link

Publications and source records attributed to Thomas M Link.

At least 37 records · Page 2Linked to original sources

PubMed2005

Cartilage MR imaging at 3.0 versus that at 1.5 T: preliminary results in a porcine model.

PURPOSE: To compare 1.5- and 3.0-T magnetic resonance (MR) images of porcine knee specimens containing artificial cartilage lesions in terms of accuracy of lesion depiction, image quality, and signal-to-noise ratio (SNR). MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant study had institutional review board approval, and informed consent was obtained from the human volunteers. Two fat-saturated cartilage MR imaging sequences (an intermediate-weighted fast spin-echo [SE] sequence and a spoiled gradient-echo [GRE] sequence) were optimized for imaging at 3.0 T in two human volunteers and then used to image 10 porcine knees in which 29 artificial cartilage lesions had been created. Corresponding sequences were used at 1.5 T for all specimens. Images were assessed by two radiologists in consensus, and diagnostic performance in lesion depiction was determined by using macroscopic findings in specimen slices as a reference standard. SNRs were also calculated. For statistical analysis, the McNemar test of discordant pairs was used with a level of significance of P < .05. RESULTS: The best diagnostic performance for both the intermediate-weighted fast SE and the spoiled GRE sequences was achieved at 3.0 T. With use of corresponding fat-saturated intermediate-weighted fast SE sequences with an identical acquisition time (9 minutes 44 seconds), 26 (90%) of 29 lesions were detected at 3.0 T, while 18 (62%) were detected at 1.5 T. With use of fat-saturated spoiled GRE sequences, 24 (83%) of 29 lesions were detected at 3.0 T (acquisition time, 8 minutes 48 seconds), and 23 (79%) lesions were detected at 1.5 T (acquisition time, 11 minutes 14 seconds). The rate of correct lesion grade assessment was 65% (17 of 26 lesions) at 3.0 T and 61% (11 of 18 lesions) at 1.5 T with the intermediate-weighted fast SE sequences and 83% (20 of 24 lesions) at 3.0 T and 70% (16 of 23 lesions) at 1.5 T with the spoiled GRE sequences. Both subjective evaluation of image quality and SNR values were significantly higher at 3.0 T (P < .05). CONCLUSION: In this animal model, MR imaging at 3.0 T increased the accuracy of cartilage lesion assessment when compared with imaging at 1.5 T. Image quality and SNR were highest at 3.0 T.

Animals↗

PubMed2005

Improved performance of hip DXA using a novel region of interest in the upper part of the femoral neck: in vitro study using bone strength as a standard of reference.

We tested the hypothesis that bone mineral density (BMD) and bone mineral content (BMC) in proximal human femur specimens in the upper neck region of interest (ROI) and femoral neck axis length (FNAL) provide a significantly better prediction of femoral bone strength than standard ROIs in vitro. BMD and BMC were measured in 110 proximal femur specimens using a standard dual-energy X-ray absorptiometry (DXA) scanner. The analysis included a new ROI in the upper neck as well as the standard ROIs. FNAL was obtained from the scan images. The specimens' failure-load was measured in a mechanical loading device, simulating a fall on the greater trochanter. For the standard ROIs, correlations between failure-load and BMD ranged from R2 = 0.64 (shaft ROI) to R2 = 0.70, p < 0.001 (femoral neck). Prediction of strength by BMD did not significantly differ from those of BMC (R2 ranging from 0.65 to 0.75, p < 0.001). In the upper neck ROI, for both BMD and BMC correlations with failure-load were higher (R2 = 0.76 and 0.81, respectively; p < 0.001). A lower, yet still significant, correlation was found between FNAL and bone strength (R2 = 0.23, p < 0.001). Normalization of failure-load with respect to FNAL did not significantly increase the correlations with densitometric measures. This study provides in vitro evidence indicating that among the ROIs of the proximal femur the newly defined upper neck ROI provides the best prediction of bone strength. Only a weak association was observed between failure load and FNAL.

Absorptiometry, Photon↗

PubMed2005

Optimization of gadodiamide concentration for MR arthrography at 3 T.

OBJECTIVE: The purpose of our study was to determine the optimal concentration of a gadolinium-based contrast agent (gadodiamide) for direct MR arthrography at 3 T compared with 1.5 T in an in vitro study. CONCLUSION: Optimized concentrations of gadolinium-based contrast agents for MR arthrography are similar at 3 and 1.5 T, although a slightly greater dilution may be useful at 3 T. Signal-to-noise ratio peak levels are significantly reduced by adding an iodinated contrast agent, relatively significantly more at 3 T than at 1.5 T.

Arthrography↗

PubMed2004

MR cystography for bladder tumor detection.

The purpose of the study was to assess the diagnostic performance of MR cystography with virtual cystoscopic and multiplanar reconstructions for detection of malignant bladder tumors. Thirty-two patients with 43 bladder tumors previously confirmed by cystoscopy (mean size 2.5 cm; 0.4-9.1 cm;) were examined at 1.5 T with a three-dimensional T2-weighted turbo spin echo sequence (TR=2911 ms, TE=500 ms, echo train length 256). Virtual cystoscopic reconstructions (VC) and multiplanar reconstructions (MPR) were obtained and analyzed separately by three radiologists without knowledge of the tumor location. Intraoperative or cystoscopic findings served as standard of reference. Sensitivities and specificities were calculated using a receiver-operating characteristic analysis with five levels of confidence. Area-under-curve values were similar for MPRs (0.952), VC (0.932) and the combination of both methods (0.954). Optimal sensitivity was 92.3% for MPR and 90.7% for VC, respectively, with a specificity of 91.1% for MPR and 90.4% for VC. The combination of MPR and VC resulted in a sensitivity of 90.7% and specificity of 94.0%. MR cystography is a promising, completely non-invasive technique for the detection of bladder lesions with a high diagnostic performance.

Aged↗

PubMed2004

In vitro and in vivo spiral CT to determine bone mineral density: initial experience in patients at risk for osteoporosis.

PURPOSE: To evaluate, both experimentally and in vivo, if nondedicated standard spiral computed tomography (CT) may be used to obtain reliable bone mineral density (BMD) data. MATERIALS AND METHODS: Twenty lumbar spine specimens from human cadavers were examined with standard quantitative CT and spiral CT. In addition, 50 patients with a history of lymphoma and chemotherapy were examined. These patients underwent long-term follow-up CT to rule out tumor recurrence. Quantitative CT was performed before contrast medium administration to assess potential posttherapeutic osteoporosis. In addition, fracture status of the spine was determined. Mean BMD values and SDs were calculated, and relationships between measurements obtained with quantitative CT and spiral CT were assessed with linear regression analysis and two-tailed tests of significance (t test). A linear fit was used to calculate quantitative CT data from spiral CT values. RESULTS: For the specimens, a coefficient of determination (r(2) = 0.99, P <.001) was found between BMD measurements obtained with quantitative CT and those obtained with spiral CT. Mean BMD in specimens was 63.6 mg/mL +/- 36.6 with quantitative CT and 74.4 mg/mL +/- 38.2 with spiral CT. Mean BMD in patients was 105.0 mg/mL +/- 34.6 with quantitative CT and 139.5 mg/mL +/- 42.7 with contrast medium-enhanced spiral CT. A coefficient of determination (r(2) = 0.91, P <.001) was obtained between these measurements. Mean BMD from L1 through L3 vertebrae was calculated, and spiral CT data were multiplied by 0.77 to yield quantitative CT data. Differences in BMD were significant (P <.05) for patients with (n = 9) and those without fractures (n = 41), as determined with spiral CT and quantitative CT. CONCLUSION: Correlations between BMD data obtained with spiral CT and standard quantitative CT were highly significant. By using a conversion factor, BMD measurements can be determined with routine abdominal spiral CT scans.

Aged↗

PubMed2004

Assessment of vascular invasion in pancreatic head cancer with multislice spiral CT: value of multiplanar reconstructions.

The use of multiplanar reconstructions (MPRs) generated from multislice spiral CT (MSCT) data sets in the preoperative assessment of vascular invasion in pancreatic cancer was evaluated. Forty patients underwent biphasic high-resolution MSCT prior to surgery for pancreatic head cancer. Image reconstruction included thin-slice axial, sagittal and coronal MPRs as well as an MPR perpendicular to the course of a major peripancreatic vessel in proximity to the tumor. CT criteria for vascular invasion were: (1) circumferential involvement >180 degrees and (2) vessel narrowing. Imaging findings of 52 vessels were correlated with surgical and histopathological reports. Regarding the CT criterion circumferential involvement, vascular invasion was demonstrated on axial MPRs with a sensitivity and specificity of 58 and 97%. For the assessment with coronal and sagittal MPRs sensitivity was only 47%. Vascular invasion was recognized best on perpendicular MPRs with a sensitivity, specificity and accuracy of 74, 97 and 88%, respectively. Vessel narrowing was a less reliable CT criterion for vascular invasion, mainly due to the lower specificity of 91% obtained with each available MPR. Thin-slice MPRs oriented perpendicularly to a possibly invaded vessel exactly depict the grade of circumferential involvement and thus have the capability to improve the assessment of vascular invasion in pancreatic cancer.

Adenocarcinoma↗

PubMed2004

Bone imaging: traditional techniques and their interpretation.

Patients with osteoporosis have to be diagnosed at an early stage to prevent fractures, the worst complication of this disease. Currently, measurements of bone mineral density (BMD) are used most frequently in the diagnosis of osteoporosis. According to the World Health Organization, osteoporosis is defined on the basis of BMD measurements that are compared with those of a healthy, young, female population. The best established techniques to measure BMD are dual x-ray absorptiometry of the lumbar spine and proximal femur and quantitative computed tomography of the lumbar spine. Conventional radiographs are not suited to assess bone mass, but they are important in the diagnosis and differential diagnosis of osteoporotic fractures. Quantitative ultrasound and structure analysis, based on high-resolution magnetic resonance imaging and computed tomography, are newer techniques in the diagnosis of osteoporosis that also focus on the assessment of bone structure.

Absorptiometry, Photon↗

PubMed2004

Current diagnostic techniques in the evaluation of bone architecture.

Bone quality, which encompasses trabecular bone and cortical bone architecture, bone mineralization, turnover, and microdamage, is an essential component of bone strength. Therefore, bone quality, bone density, and total content are the most important parameters in the diagnosis of osteoporosis. Noninvasive assessment of bone quality has recently received considerable attention because bone density alone is not a surrogate for fracture prevalence and occurrence, and does not completely explain the therapeutic efficacy of emerging treatments. This paper will focus on the noninvasive assessment of trabecular bone architecture, one of the factors that governs bone strength and may be categorized as a contributor to bone quality. The methodologies described will include magnetic resonance imaging, clinical multislice spiral computed tomography, and micro-computed tomography, along with computerized analysis of radiographic patterns of trabecular bone.

Aged↗

PubMed2004

Determinants and heterogeneity of mechanical competence throughout the thoracolumbar spine of elderly women and men.

Vertebral fractures represent the hallmark of osteoporosis. Here, we test the hypotheses that (sub)cortical bone strength and density predict failure better than trabecular core strength and density, and that elderly women display lower failure stress of thoracic vertebrae than men. We examined the vertebral bodies T3 to L5 in 39 spines from elderly donors (23 women; 16 men; age 79 +/- 11 years). Peripheral quantitative computed tomography was used to measure total, trabecular, and (sub)cortical bone density. Mechanical tests were performed in functional spinal units, planoparallel sections of vertebrae, trabecular cores, and (sub)cortical ring specimens. The failure stress decreased with descending vertebral level. Failure stress was highest for the (sub)cortical rings and planoparallel sections and lowest for the trabecular core. The failure stress did not differ significantly between men and women. Mechanical strength of the functional unit was more strongly correlated with the strength of the (sub)cortical ring (r = 0.78) than with that of the trabecular core (r = 0.62). However, total density was more highly correlated with mechanical strength of the same and remote vertebrae (r = 0.63) than trabecular (r = 0.50) or (sub)cortical density (r = 0.36), respectively. The results show that vertebral strength is similar in elderly women and men. Strength of (sub)cortical bone provides significantly better prediction of strength of functional spinal units than that of the trabecular core. However, total density predicts functional segment failure stress with higher accuracy than (sub)cortical or trabecular density and is thus recommended for predicting fracture strength clinically.

Aged↗

PubMed2004

A pilot, two-year longitudinal study of the interrelationship between trabecular bone and articular cartilage in the osteoarthritic knee.

OBJECTIVE: To examine the relationship between structural changes of trabecular bone and cartilage, in patients with varying degrees of osteoarthritis (OA) over 2 years, using magnetic resonance imaging. METHODS: High-resolution, axial images were acquired for assessing trabecular bone structure, using a 3-D fast gradient-echo sequence. High-resolution, fat-suppressed, sagittal images were acquired for assessing cartilage structure, using a 3-D spoiled gradient-echo sequence. In a subset of the patients, sagittal images were acquired for measuring T(2) relaxation time, using a 2-D dual-echo spin echo sequence. RESULTS: A large variation in bone and cartilage parameters is evident among individual subjects in each group, however, group-specific means demonstrate decreasing trends (in bone and cartilage parameters) in osteoarthritic subjects (especially in mild OA subjects). The mean T(2) increased significantly (P<0.05) between the baseline and follow-up exams for all cartilage compartments except the lateral tibia. A positive relationship was established between cartilage changes and localized bone changes closest to the joint line, while a negative relationship was established between cartilage changes and global bone changes farthest from the joint line. CONCLUSION: This study quantifies the changes in bone and cartilage structural parameters over time, and demonstrates a longitudinal relationship between the morphological changes in bone and cartilage structure in patients with varying degrees of OA. Although a large variation of bone and cartilage changes is apparent among subjects, significant trends are evident in a relatively small sample size, with a short follow-up duration.

Adult↗

PubMed2004

Trabecular bone structure of the distal radius, the calcaneus, and the spine: which site predicts fracture status of the spine best?

RATIONALE AND OBJECTIVES: To compare trabecular bone structure measures obtained in magnetic resonance images of the distal radius and the calcaneus as well as computed tomographic images of the spine versus bone mineral density (BMD) of the spine and the calcaneus in the prediction of osteoporotic spine fracture status. MATERIAL AND METHODS: High-resolution magnetic resonance images of the calcaneus and the distal radius and thin-section computed tomographic images of thoracic and lumbar vertebrae were obtained from 74 cadavers. Structure analysis was performed using parameters analogous to standard histomorphometry. BMD of the spine was determined by using quantitative computed tomography and of the calcaneus by using dual x-ray absorptiometry. Spine radiographs of these cadavers were assessed concerning vertebral deformities. RESULTS: The diagnostic performance in differentiating fracture and nonfracture subjects was highest for structure parameters in the spine and slightly lower for these parameters in the distal radius and for BMD of the spine. CONCLUSION: In this study structure parameters in the spine were best suited to predict the osteoporotic fracture status of the spine.

Absorptiometry, Photon↗

PubMed2003

Reproducibility and side differences of mechanical tests for determining the structural strength of the proximal femur.

UNLABELLED: In this experimental study, we evaluated the reproducibility error of mechanical strength tests of the proximal femur when simulating a fall on the trochanter. Based on side differences in femoral failure loads in 55 pairs of femora, we estimated the upper limit of the precision error to be 15% for the side impact test, whereas the intersubject variability was >40%. INTRODUCTION: Mechanical tests are commonly used as the gold standard for determining one of the main functions of bones, that is, to provide mechanical strength. However, it is unknown what magnitude of error is associated with these tests. Here we investigate the precision error and side difference of a side impact test of the proximal femur. MATERIALS AND METHODS: BMC was measured using DXA in 54 pairs of femora from donors 79.0 +/- 10.6 years of age. Bones were tested to failure, simulating a fall on the greater trochanter. RESULTS: Failure loads were 3951 +/- 1659N (CV% = 42%) on the right and 3900 +/- 1652N (CV% = 42%) on the left (no significant side difference). The average random difference of femoral BMC was 7 +/- 7% and that of femoral failure loads was 17 +/- 12%. The correlation between BMC and failure load was 79% (r2), but the association between side differences in failure load with those in BMC was only 4%. When confining the analysis to pairs with less than 5% differences in BMC (n = 31), side differences in failure loads were 15 +/- 13%. When correcting failure loads for side differences of BMC, the difference was 16 +/- 15% CONCLUSIONS: These results suggest that the upper limit of the precision error for femoral strength tests is approximately 15% in a side impact configuration. Given the large intersubject variability of failure loads, this test provides an efficient tool for determining the structural strength of the proximal femur in a fall.

Biomechanical Phenomena↗

PubMed2003

Quantification of breast tumor microvascular permeability with feruglose-enhanced MR imaging: initial phase II multicenter trial.

PURPOSE: To investigate use of the macromolecular contrast agent feruglose for differentiating and grading of human benign and malignant breast tumors on the basis of their microvascular characteristics. MATERIALS AND METHODS: Sixty-three women with 63 primary breast lesions were examined with dynamic T1-weighted gradient-echo magnetic resonance (MR) imaging after intravenous injection of feruglose. A two-compartment unidirectional kinetic model applied to the dynamic data yielded estimates of the endothelial transfer coefficient, KPS, and the fractional plasma volume of the tumors. These MR imaging-derived parameters were correlated with the histologic tumor grade and quantified according to the Scarff-Bloom-Richardson (SBR) score by means of Pearson product moment correlation analyses. Differences between malignant and nonmalignant breast lesions with respect to KPS for feruglose were evaluated by means of the chi2 test and by calculating the sensitivity, specificity, and positive and negative predictive values. RESULTS: Histologic analysis revealed 26 benign and 37 malignant tumors. A moderate yet statistically significant correlation between KPS and SBR score was found (R = 0.496, P <.001). No significant correlation was observed between fractional plasma volume and SBR score (R = 0.085, P =.507). The KPS values were zero for 19 (73%) of the 26 benign tumors and were greater than zero for 27 (73%) of the 37 carcinomas. This distribution was significantly different (chi2 = 13.035, P =.001). With the criterion KPS > 0 in carcinomas, sensitivity was 0.73, specificity was 0.73, and the positive predictive value was 0.79. CONCLUSION: Quantitative measures of tumor microvascular permeability can be used for breast tumor characterization. The probability of breast tumor microvascular hyperpermeability to be associated with malignancy is 79%.

Adult↗

PubMed2003

Targeting of hematopoietic progenitor cells with MR contrast agents.

PURPOSE: To label human hematopoietic progenitor cells with various magnetic resonance (MR) imaging contrast agents and to obtain 1.5-T MR images of them. MATERIALS AND METHODS: Hematopoietic progenitor cells, labeled with ferumoxides, ferumoxtran, magnetic polysaccharide nanoparticles-transferrin, P7228 liposomes, and gadopentetate dimeglumine liposomes underwent MR imaging with T1- and T2-weighted spin-echo and fast field-echo sequences. Data were analyzed by measuring MR signal intensities and R1 and R2* relaxation rates of labeled cells and nonlabeled control cells. Mean quantitative data for the various contrast agent groups were assessed for significant differences compared with control cells by means of the Scheffe test. As a standard of reference, MR imaging data were compared with electron microscopic and spectrometric data. RESULTS: For all contrast agents, intracellular cytoplasm uptake was demonstrated with electron microscopy and was quantified with spectrometry. When compared with nonlabeled control cells, progenitor cells labeled with iron oxides showed significantly (P <.05) increased R2*. Cells labeled with gadopentetate dimeglumine liposomes showed significantly increased R1. Detection thresholds were 5 x 10(5) cells for gadopentetate dimeglumine liposomes and ferumoxtran, 2.5 x 10(5) cells for ferumoxides and P7228 liposomes, and 1 x 10(5) cells for magnetic polysaccharide nanoparticles-transferrin. CONCLUSION: Hematopoietic progenitor cells can be labeled with MR contrast agents and can be depicted with a standard 1.5-T MR imager.

Cell Survival↗

PubMed2003

Highly efficient paramagnetic labelling of embryonic and neuronal stem cells.

Recent developments in stem cell and gene therapy will require methods to monitor stem cell survival and integration repeatedly and non-invasively with a high temporal and spatial resolution in vivo. The aim of this study was to visualise embryonic and neuronal stem cells with standard contrast agents using a conventional clinical 1.5-Tesla scanner. We therefore modified standard transfection protocols including lipofection (Lipofectin and Lipofectamine) and calcium phosphate transfection for the efficient uptake of paramagnetic particles [gadolinium-diethylene triamine penta-acetic acid (Gd-DTPA)] in stem cells. Using this approach we obtained intracellular labelling efficiencies of up to 83%. Neither the proliferation capacity nor the differentiation efficiency was affected. Identical differentiation of labelled and unlabelled embryonic and neuronal cells was observed. The established labelling techniques used in this study displayed high labelling efficiencies in embryonic and neuronal stem cells without any alterations of cellular biology; therefore this approach might be a suitable method for targeting stem cells.

Animals↗

PubMed2003

Osteoporosis imaging.

Because osteoporotic fractures may be prevented, diagnostic techniques are essential in the assessment of osteoporosis. Conventional radiographs of the spine are not suited for diagnosing early osteoporosis, but they show fractures that may have no clinical symptoms. The radiologist should be aware of the enormous significance of these fractures for future osteoporotic fractures. Bone mass measurements are standard techniques in the diagnosis of osteoporosis, which are the basis of the WHO definition of osteoporosis. In this article the authors presented these standard techniques and newer diagnostic techniques that provide insights in the structure of trabecular bone.

Diagnostic Imaging↗

PubMed2003

Macromolecular contrast medium (feruglose) versus small molecular contrast medium (gadopentetate) enhanced magnetic resonance imaging: differentiation of benign and malignant breast lesions.

RATIONALE AND OBJECTIVES: To compare the diagnostic performance of the blood pool agent feruglose and the standard extracellular contrast agent gadopentetate in their abilities to differentiate benign and malignant breast tumors. PATIENTS AND METHODS: Fourteen women, aged 35-77 years (mean, 55 years), with 19 breast lesions underwent dynamic fast field echo 14/1/30 degrees (TR/TE/alpha) magnetic resonance imaging of the breast after bolus injection of feruglose (Clariscan; Amersham Health, Amersham, UK: dose, 2 mg Fe/kg) and an additional, comparative gadopentetate (dose, 0.2 mmol gadolinium/kg)-enhanced fast field echo 10/4/30 degrees (TR/TE/alpha) magnetic resonance study within 1-11 days (mean, 4.8 days) before or after the feruglose study. All breast tumors were surgically excised within 1-6 days (mean, 2.5 days) after completion of the magnetic resonance studies. Data were analyzed by measuring quantitative enhancement data and qualitatively by categorizations of the shape of the tumor enhancement curves. Group differences between quantitative data of the two contrast agents and between benign and malignant tumors were evaluated using a two-tailed paired-sample t test. Differences in curve type distribution between benign and malignant tumors were tested with the chi2 test. RESULTS: Histopathology showed a spectrum of 10 benign and nine malignant breast lesions: five mastopathies, two fibroadenomas, two chronic inflammations, and one papillomatosis, as well as five invasive ductal carcinomas and four invasive lobular carcinomas. Substantial differences were observed between feruglose- and gadopentetate-enhanced images: the mean tumor deltaSI(%) peak enhancement and wash-in rate were significantly higher for gadopentetate- as compared with feruglose-enhanced images (P < .05). Using either contrast agent, morphologic enhancement characteristics showed a considerable overlap between benign and malignant breast lesions. However, the kinetic enhancement profiles of benign and malignant lesions were significantly different based on feruglose-enhanced data (chi2 = 9.017; P = .0027) but not gadopentetate-enhanced data (chi2 = 2.239; P = .3264). CONCLUSION: Compared with gadopentetate, the new blood pool agent feruglose provided an improved characterization of the evaluated breast lesions; however, at the cost of weaker overall tumor enhancement.

Adult↗

PubMed2003

Detection and quantification of breast tumor necrosis with MR imaging: value of the necrosis-avid contrast agent Gadophrin-3.

RATIONALE AND OBJECTIVES: The authors evaluated the use of T1-weighted magnetic resonance (MR) imaging with Gadophrin-3 enhancement and of plain T2-weighted MR imaging to detect and quantify breast tumor necrosis. MATERIALS AND METHODS: Twenty EMT-6 tumors (mouse mammary sarcoma), implanted into the mammary fat pad of BALB/c-AnNCrl mice, underwent MR imaging with plain T2-weighted and T1-weighted fast field echo sequences before and 24 hours after injection of Gadophrin-3, a new necrosis-avid contrast agent. Tumor necrosis on MR images was quantified by means of a dedicated segmentation program and was correlated with histologic findings. RESULTS: In all tumors a central necrosis was revealed by histopathologic analysis, and central enhancement was seen with Gadophrin-3 on T1-weighted images. Small tumors (diameter, < 1 cm) showed an inhomogeneous central enhancement, whereas larger tumors (diameter, > 1 cm) enhanced mainly in the periphery of necrotic tissue. Plain T2-weighted images showed a hyperintense central area in only three of 20 cases with a large central necrosis. CONCLUSION: Gadophrin-3-enhanced T1-weighted images are superior to plain T2-weighted images for the detection of necrosis in a murine tumor xenograft model.

Animals↗