Dynamic Gd-DTPA Research Articles

Chemotherapy Response Monitoring of Colorectal Liver Metastases by Dynamic Gd-DTPA–Enhanced MRI Perfusion Parameters and 18F-FDG PET Metabolic Rate

In this study, we examined the in vivo relationship between functional tumor vasculature, determined by dynamic contrast-enhanced (DCE-) MRI, and tumor metabolism, determined by dynamic (18)F-FDG PET, during cytotoxic treatment of patients with colorectal liver metastases. Twenty-three patients underwent DCE-MRI (using gadolinium dimeglumine) and dynamic (18)F-FDG PET at baseline and after 3 treatment cycles, unless treatment was terminated because of toxicity. Parameters for vasculature (rate constant between extravascular extracellular space and blood plasma [k(ep)] and volume transfer constant [K(trans)]), extracellular space (v(e)), tumor size (the maximal axial diameter of each included lesion [MAD]), and metabolism (glucose metabolic rates [MR(glc)]) were derived, and changes during treatment were correlated. Overall survival (OS) and progression-free survival (PFS) served as outcome measures for the predictive abilities of pretreatment parameters and of treatment-related parameter changes. Pretreatment MR(glc) and MAD were individually predictive for OS and PFS. During treatment, K(trans) increased significantly, but this increase could not be confirmed in a lesion-by-lesion analysis. MR(glc) decreased significantly (P < 0.001). No correlations were found for changes in DCE-MRI parameters and DeltaMR(glc). No relationship was found between changes in DCE-MRI parameters and OS or PFS. DeltaMR(glc) was able to predict OS (P = 0.008) after correction for confounders. The efficacy of cytotoxic chemotherapy assessed by reduction in tumor metabolism does not depend on pretreatment properties of the tumor vasculature determined by DCE-MRI. Cytotoxic chemotherapy does not alter DCE-MRI-derived properties of tumor vasculature but decreases glucose consumption of tumor cells.

Can DCEMRI assess the effect of green tea on the angiogenic properties of rodent prostate tumors?

The purpose of this research was to test whether dynamic contrast enhanced MRI could assess the effect of green tea on the angiogenic properties of transplanted rodent tumors. Copenhagen rats bearing AT6.1 prostate tumors inoculated in the hind limbs were randomly assigned to cages in which they were allowed to only drink either plain water (control group) or water containing green tea extract (treated group). Assignments were made after a baseline MRI experiment (week 0) was performed on each rat at 4.7 T. All the rats were subsequently imaged at day 7 (week 1) and day 14 (week 2) to follow tumor growth and vascular development. The two-compartment pharmacokinetic model was used to analyze the dynamic contrast Gd-DTPA enhanced MRI data on a pixel-by-pixel basis over the tumor area to obtain the volume transfer constant ( K trans) and extravascular extracellular space ( v e). An identity Chi-squared test showed that the distributions of averaged histograms ( n = 6) of K trans and v e were significantly different from week 0 to both weeks 1 and 2 ( p < 0.001) in both the control and the treated rats due to increasing areas of tumor necrosis. However, the tumor growth rate was statistically indistinguishable between control and treated rats. There was no significant difference in the distributions of K trans and v e between control and treated rats. The results showed that no effects of green tea on tumor micro-vasculature were measurable by dynamic Gd-DTPA enhanced MRI.

Groove pancreatitis: MRI and pathologic findings

Our purpose is to describe the MRI findings with pathologic correlation, in five patients with groove pancreatitis, a specific form of chronic pancreatitis affecting the groove between the pancreatic head, the common bile duct and duodenum. Five patients with pathologically proven (four cases) and clinical and MRI findings (follow-up) consistent with the diagnosis of groove pancreatitis (one case) were reviewed. Three patients underwent cephalic pancreatoduodenectomy (Whipple procedure) due to severe duodenal stenosis; MRI findings were correlated with the histological findings. In all patients a mass was seen affecting the groove between the pancreatic head and the duodenum. Precontrast images demonstrated hypointense tissue relative to pancreatic parenchyma on T1-weighted images and iso to slightly hyperintense tissue on STIR and T2-weighted images. Postcontrast dynamic Gd-DTPA images, showed peripheral mass enhancement on immediate postgadolinium images and progressive and centripetal mass enhancement on delayed images with good delineation of multiple cysts. Histologically, fibro-inflammatory tissue was demonstrated in the groove and the duodenal wall with obliterative concentric scarring of the distal common bile duct. MRI findings are demonstrative of the pathologic features characteristic of this entity: the fibrous tissue in the pancreaticoduodenal groove, the duodenal wall inflammation and the groove and/or duodenal wall cyst formation.

Evaluation of MRI in Diagnosing Hilar Cholangiocarcinoma

Objective: To investigate the clinical application of MRI in the diagnosis and preoperative evaluation of hilar cholangiocarcinoma (HC). Methods: Thirty-four cases of HC were examined with 1.5T super-conduct MR unit. The plain MRI and MRCP were followed by dynamic Gd-DTPA (0.1 mmol/kg) contrast-enhanced scanning, which was repeated at 30 s intervals in the first 3 min with the patient being remained in the same position. Delayed scanning was done at 5, 8, 10, 12 and 15 min respectively. 3DDCE- MRA was performed in arterial and portal venous phase with an additional bolus injection of 15-20 mL Gd-DTPA (0.15-0.20 mmol/kg). The contrast time-signal curve of both the liver and the tumor was drawn from DCE imaging, and both arterial and portal venous phase imaging were reconstructed with MIP. MRI findings were compared with surgical findings and pathology. Results: Hilar lesion, intrahepatic ducts dilatation and disconnect of main hepatic duct were shown in all cases. Thirty-one cases had tumor-delayed enhancement. In 3D-DCE-MRA, spiral artery deformed was displayed in 6 cases, infiltration, encasement or occlusion of portal vein was displayed in 18 cases. The accuracy of assessing tumor unresectability and resectability by preoperative MRI was 95.0% (19/20) and 78.6% (11/14) respectively. The total accuracy rate of MRI assessing was 88.2% (30/34). Conclusion: All-in-one MR, including plain MR, MRCP, MR DCE and 3D-DCE-MRA, can accurately show the lesions and involvement of neighbouring tissues. It was of great value in diagnosis and preoperative evaluation of HC.

Detection of hepatocellular carcinoma: comparison of Gd-DTPA- and ferumoxides-enhanced MR imaging

The aim was to compare the diagnostic performance of dynamic Gd-DTPA- and ferumoxides-enhanced MRI for hepatocellular carcinoma (HCC). Twenty-five patients with chronic hepatitis or liver cirrhosis underwent both dynamic gadopentetate- and ferumoxides-enhanced MRI studies of the liver for HCC detection on the same day. MR data of both studies were retrospectively and independently analyzed. Two observers determined in consensus the grade of diffuse fibrotic liver changes (mild, moderate or severe) and the number of focal lesions. HCCs were confirmed by histology (n=22) and/or follow-up studies for at least six months (n=64). Differences in results obtained from both MR data sets were tested for significance with the McNemar's test (p<0.05). Ferumoxides-enhanced MR images detected 84 of 99 hepatic lesions, including 82 of 86 HCCs and 2 false positive, nonmalignant lesions, while Gd-DTPA-enhanced MR images detected 92 of 99 hepatic lesions, including 81 of 86 HCCs and 11 false positive, nonmalignant lesions. Sensitivity of MRI for detection of HCCs was not significantly different between ferumoxides-enhanced (95.3%; p>0.05) and Gd-DTPA-enhanced scans (94.2%). Gd-DTPA- and ferumoxides-enhanced MRI perform equally well for HCC detection. The majority of small hypervascular hepatic lesions, detected on dynamic Gd-DTPA-enhanced MRI but not on ferumoxides-enhanced MRI, represent no HCCs.

Dynamic gadolinium uptake in thermally treated canine brain tissue and experimental cerebral tumors.

Thermal coagulation of cerebral tumors induces reactive changes within adjacent brain tissue, which appear as Gd-DTPA enhancement in MR images. This makes assessment of therapeutic success difficult to establish radiographically because the reactive changes can mimic residual tumor. Dynamic Gd-DTPA uptake curves in reactive tissue and tumor were investigated to assess the utility of contrast enhanced (CE)-dynamic MRI to distinguish reactive changes from residual tumor in a canine model. Cerebral thermal necrosis was induced using a 980 nm laser in 11 dogs with intracerebral transmissible venereal tumors (TVTs). A fast spin-echo T1-weighted imaging sequence was used for CE-dynamic MRI. Gd-DTPA uptake data were acquired with 10-second temporal resolution and for untreated TVTs for reactive tissue using a sigmoidal-exponential model. Characteristic gadolinium uptake curves were measured and characterized for reactive brain tissue, and untreated and treated TVTs. Both early and delayed dynamic responses were significantly different in reactive brain tissue compared with TVT. Reactive thermal changes in otherwise normal brain tissue can be distinguished from residual tumor after cerebral thermal therapy using CE-dynamic MRI.

Quantitative Estimation of Microvascular Permeability in Human Brain Tumors: Correlation of Dynamic Gd-DTPA–enhanced MR Imaging with Histopathologic Grading

There are several clinical demands for a noninvasive method to characterize brain tumors (eg, such a technique could guide a surgeon to the most malignant spot before a biopsy). Other potential utilities for permeability measurements might be the follow-up after therapy (eg, to monitor the success of chemotherapy or to differentiate radiation necrosis and postsurgical scar tissue from recurring tumor, or to noninvasively monitor the efficacy of new treatments of gliomas, such as antiangiogenic pharmaceuticals). Several publications have focused on using imaging techniques to assess the malignancy of gliomas (1–3). Most of the magnetic resonance (MR) studies investigate the correlation between fractional blood volume (fBV) and tumor grade, using first-pass techniques after bolus contrast agent administration, based on the magnetic susceptibility contrast phenomenon and the resulting changes in T2* (1–4). Alternatively, a method based on the relaxivity effect of contrast agents (ie, T1 measurements) can be used (5,6). From all of these studies, whether they are based on T2* or T1 effects of a contrast agent, there is consensus that increased malignancy is associated with increased blood volume and that, in principle, it might be possible to differentiate between lowand high-grade gliomas. However, no statistically significant difference is found between the blood volumes of all of the tumors of different grades (5,6). The aim of this study was to implement a technique that can be used to quantify fBV as well as the microvascular permeability in patients with brain tumors and to assess whether permeability quantifications improve the noninvasive assessment of tumor malignancy.

Changes in tumor oxygenation/perfusion induced by the no donor, isosorbide dinitrate, in comparison with carbogen: monitoring by EPR and MRI

Purpose: In an effort to improve radiotherapy treatments, methods aimed at increasing the quantity of oxygen delivered to tumors were investigated. The aim of this study was to evaluate the effect of one nitric oxide (NO) donor (isosorbide dinitrate) on pO 2 and blood flow in a murine tumor model. The effect was compared to carbogen, used as a reference treatment. Methods and Materials: Thirty-six liver tumors implanted in mouse thighs were imaged using magnetic resonance imaging (MRI) at 4.7 Tesla with dynamic Gd-DTPA and blood oxygen level-dependent (BOLD) contrast-enhanced imaging after administration of isosorbide dinitrate or carbogen. The effect on the pO 2 was also tested by EPR oximetry (1.1 GHz) on 52 mice. Results: A significant increase in MRI intensity was observed for both treatments in comparison with the control group. EPR oximetry showed a dose-dependant increase in tumor pO 2 for isosorbide dinitrate (by 5.9 mmHg at 0.2 mg/kg) and a substantially greater change for carbogen breathing (by 23 mmHg). Conclusion: Both tumor blood flow and pO 2 were increased by isosorbide dinitrate and carbogen. Carbogen is more efficient than isosorbide dinitrate in increasing the BOLD image intensity, as well as the tumor pO 2, but as efficient as isosorbide dinitrate in the Gd-DTPA contrast-enhanced imaging. We conclude that the effects of carbogen on improving tumor pO 2 involve both improved blood flow and improved hemoglobin oxygenation, whereas the effects of isosorbide dinitrate are predominantly mediated by improved blood flow alone.

Absolute renal blood flow quantification by dynamic MRI and Gd-DTPA.

The aim of this study was to demonstrate the feasibility of the absolute renal blood flow quantification using MRI and injection of contrast media. Using a T1-weighted fast gradient sequence following an intravenous bolus injection of Gd-DTPA, dynamic images of the kidney were obtained in patients with well-functioning native kidneys (n = 7) or transplant (n = 9), with significant renal artery stenosis (n = 4) and with renal failure (n = 7). After signal intensity calibration, the absolute renal perfusion was equal to the wash-in slope of the renal transit curve divided by the contrast medium concentration at the peak of the bolus in the aorta. The cortical blood flow was 2.54+/-1.16 ml/min per gram in well-functioning kidneys decreasing to 1.09+/-0.75 ml/min per gram in case of renal artery stenosis (p = 0.04) and to 0.51+/-0.34 ml/min per gram in case of renal failure (P<0.001). These measurements were in agreement with previous results obtained by other methods. A standard MRI imaging sequence and a simple model can provide realistic quantitative data on renal perfusion. This work justifies further studies to compare this model with a gold standard for renal blood flow measurements.

Contrast enhanced dynamic MRI of cervical carcinoma during radiotherapy: early prediction of tumour regression rate.

This prospective study investigated the relationship between changes in the MRI dynamic enhancement of cervical carcinoma early during radiotherapy, and tumour regression rate throughout radiotherapy. A total of 36 MRI examinations was performed in seven patients with cervical carcinoma, including a T2 weighted sequence weekly during radiotherapy and also a multislice dynamic Gd-DTPA enhanced sequence before and after the first 2 weeks of radiotherapy. Tumour enhancement was determined on dynamic images using a region of interest and signal-to-noise ratio method. Serial tumour volumes over time on T2 weighted images were estimated using the Cavalieri method of modern design-based stereology to obtain tumour regression rate. It was found that peak and mean enhancement prior to radiotherapy ranged from 3.0 to 13.3, and from 1.9 to 12.2, respectively. After 2 weeks of radiotherapy, peak and mean enhancement ranged from 7.5 to 13.0, and from 6.3 to 10.6, respectively. The change in peak and mean tumour enhancement between dynamic scans ranged, respectively, from -2.0 to 8.4 and from -4.5 to 8.5. Tumour volume decreased exponentially with time (p < 0.01). Tumour regression rates ranged from 2.0% to 15.2% per day, and correlated positively with changes of both peak and mean tumour enhancement (p < 0.01). It is concluded that MRI dynamic enhancement during the first 2 weeks of radiotherapy may provide early prediction of tumour regression rate, and therefore be of value in designing treatment schedules for cervical carcinoma.

Phantom and in vivo study of the look–locher T 1 mapping method

This paper describes and tests the LL-EPI method for obtaining quantitative T 1 estimates in a few seconds thereby allowing dynamic T 1 studies. It is shown that the method works even when there is an inflow into the imaged volume, e.g., in a vessel. No calibration is needed. The method has been tested in a phantom study with several different scan parameter set-ups, with and without inflow. The method shows robustness and individual scan parameters and inflow rates do not influence the ability to calculate the Gd-DTPA concentration. Linearity prevail between the measured 1/T 1 and the Gd-DTPA concentration in the range 150 < T 1 < 2500 ms. In a dynamic Gd-DTPA phantom study, it was shown that the dynamic LL-EPI T 1 mapping technique was three times more sensitive than the signal from a T ∗ 2-weighted EPI sequence. In an in vivo study, dynamic T 1 mapping of the Gd-DTPA uptake in a meningioma was performed. Inspection of the uptake curves indicates that the method is feasible in clinical perfusion studies.

Invasive adenocarcinoma of the uterine cervix: MR imaging

The detection of adenocarcinoma of the cervix is difficult in clinical examination, leading to poor prognoses. We evaluated MR appearances of 23 patients with adenocarcinoma of the cervix and appearances of 65 patients with cervical SCCs were also evaluated for comparison. Both T2-weighted spin echo, dynamic and postcontrast Gd-DTPA enhanced techniques were obtained at a 1.5 Tesla MR unit. The results of our study showed that adenocarcinoma of the cervix have MR imaging features which may permit distinction from SCCs which include: large tumors with preservation of endocervical epithelium, lesser contrast enhancement, and greater enhancement of the tumor periphery. Understaging may be more problematic with adenocarcinoma than SCC.

Radiological modalities in the staging of colorectal tumors: new perspectives for increasing accuracy.

The purpose of this study was to evaluate the diagnostic accuracy of contrast-enhanced endorectal MRI for the staging of rectal adenoma versus rectal carcinoma in correlation to findings from biopsy and histopathology. Ten volunteers and 20 patients underwent body-coil and endorectal MRI (1.5T supraconducting unit) using plain, T1-weighted (w) T2-w SE and TSE-w sequences, a dynamic Gd-DTPA enhanced protocol (turboFLASH), and postcontrast T1-w-SE sequences. Histopathological correlation via biopsy (n = 10) and surgical resection (n = 19) were conducted for all patients. An independent, two-observer, reader evaluation was performed and qualitative and quantitative data calculated. In volunteers and all patients endorectal MRI reliably delineated normal wall layers. Rectal adenomas (n = 7) were identified by a visualization of an intact muscularis mucosae, a homogeneous inner structure, and a significant contrast enhancement. T1 carcinomas (n = 4) were best identified in dynamic turboFLASH sequences by delineation of an intact muscularis propria. The visualization of contrast-enhancing tumor tissue was indicative of a T2 carcinoma (n = 4). All T3 (n = 3) and T4 (n = 2) carcinomas were correctly staged on dynamic and static MRI. The endorectal MRI stage agreed with the staging results from pathological study in 16 of 20 (80%) patients. Endorectal surface coil MRI provides reliable data for the preoperative staging and evaluation of rectal lesions.

Hemophilic arthropathy of the knee joint: static and dynamic Gd-DTPA ? enhanced MRI

A total of 17 patients with hemophilic arthropathy of the knee joint were studied with static and dynamic MRI before and after an IV bolus injection of Gadolinium-DTPA (Gd-DTPA; 0.1 mmol/kg body weight). The T1-weighted spin-echo (SE) and gradient-echo (fast-field echo [FFE]) sequences were applied. The FFE sequences of eight consecutive scans carried out over a time interval of 160 s were used in order to determine the time to signal intensity (SI) curves of the synovial proliferations surrounding soft tissue, bone marrow, and joint effusion. After the administration of a contrast agent, synovial proliferations exhibited an increase on FFE and SE images of 47.7 % (SD ± 14.3 %) and 37.4 % (SD ± 11.2 %), respectively, whereas muscle and fatty tissue, tendons, bone marrow, and joint effusion revealed only a minor increase in SI. The gradient of SI (ratio SI/time) of pannus was 39.6 %/min (SD ± 7.7 %/min) and differed significantly (P < 0.001) from that of bone marrow, fatty tissue, muscle tissue, tendons, and joint effusion (P < 0.05). In contrast to synovial proliferations in rheumatoid arthritis, no differentiation between various pannus vascularities based on the degree of enhancement was possible. The Gd-DTPA-enhanced MRI studies delineate and quantify the synovial proliferations in hemophilic arthropathy. Dynamic studies in hemophilic arthropathy do not provide qualitative assessment of the inflammatory process.

Dynamic Gd-DTPA enhanced MRI measurement of tissue cell volume fraction.

A new technique for measuring tissue cellular volume fraction, based on an improved modeling of the dynamic distribution of Gd-DTPA and the effect of proton exchange, is described. This technique uses peak T1 enhancement and blood Gd-DTPA concentration to compute tissue cellular volume fraction. The feasibility of this technique is demonstrated with computer simulations that explore the limits of the simplifying assumptions (small vascular space, slow vascular-extravascular proton exchange), and by direct comparison of MR and radionuclide cell fraction measurements made in muscle, liver, and tumor tissue in a rat model. The computer simulations demonstrate that with slow to intermediate vascular proton exchange and vascular fractions less than 10% the error in our cell fraction measurements typically remains less than 10%. Consistent with this prediction, a direct comparison between MR and radionuclide measurements of cell fraction demonstrates mean percent differences of less than 10%:1.9% in muscle (n = 4); 9% in liver (n = 1) and 9.5% in tumor (n = 4). Similarly, for all rats studied, the MR-measured cell fractions (muscle (0.92 +/- 0.04, n = 20); liver (0.76 +/- 0.11, n = 9); whole tumor (0.69 +/- 0.15, n = 22)) agree with the cell fraction values reported in the literature. In general, the authors' results demonstrate the feasibility of a simple method for measuring tissue cell fraction that is robust across a broad range of vascular volume, flow, and exchange conditions. Consequently, this method may prove to be an important means for evaluating the response of tumors to therapy.

Inflammatory abdominal aortic aneurysm—dynamic Gd-DTPA enhanced magnetic resonance imaging features

Inflammatory abdominal aortic aneurysm is an uncommon disorder characterized by marked thickening and extensive inflammatory changes of the aneurysmal wall. The appearances of an inflammatory abdominal aortic aneurysm on dynamic Gd-DTPA enhanced magnetic resonance imaging are described and the value of this modality in achieving a pre-operative diagnosis is emphasized.

A pharmacokinetic analysis of Gd-DTPA enhancement in MRT in breast carcinoma

Dynamic Gd-DTPA enhanced MR of the breast was performed in one single slice in 27 patients with suspicious nodular lesions. The results could be histologically verified in all cases. A rapid spin-echo sequence with a time resolution of 8.75 s was used for the dynamic examination. The signal changes were analysed using a pharmacokinetic model which allowed parametrization of the contrast enhancement and transformation of the data into colour coded parameter images. The parameters allowed reliable distinction of 9 benign from 18 malignant lesions (p < 0.05 for "amplitude", p < 0.001 for "k21"). One fibroadenoma could not be distinguished from the carcinomas. Lymph node metastases and the pharmacokinetic parameter amplitude correlated significantly (p < 0.05).

An Experimental Study on Renal Functional Disturbance in Rabbits After Acute Ureteral Obstruction With Dynamic Gd-DTPA Enhanced MR Imaging

An Experimental Study on Renal Functional Disturbance in Rabbits After Acute Ureteral Obstruction With Dynamic Gd-DTPA Enhanced MR Imaging

A fast 3D-imaging technique for performing dynamic Gd-enhanced MRI of breast lesions

The characterization of breast lesions by their Gd-enhancement profiles has been proposed as a method for differentiating benign from malignant breast lesions. The limitations of dynamic contrast enhanced 2D imaging of the breast are the low number of slices that can be acquired, and the need to know the location of the lesion a priori to correctly select the noncontiguous 2D slice locations. These problems are exacerbated when multi-focal disease is present but not anticipated. Standard fast 3D gradient-echo imaging has a variable delay between successive acquisitions. We have developed a fast 3D gradient-echo imaging technique for dynamic Gd-DTPA enhanced breast imaging which obtains multiple 3D image sets of 32 contiguous images at 44 s intervals without an interscan delay time. This rapid 3D imaging technique achieves good temporal resolution and reduces patient motion between pre- and postcontrast images while covering a much larger portion of the breast and eliminating the need for a priori knowledge concerning the location of the lesion(s) when performing Gd-enhanced dynamic MR imaging.

Rapid Measurement of Capillary Permeability Using the Early Part of the Dynamic Gd-DTPA MRI Enhancement Curve

Three fast, simple methods for measuring the permeability surface area product per unit volume, k, from the early part of the gadolinium-DTPA enhancement curve in blood-brain barrier and blood-retina barrier lesions are presented and evaluated by computer simulation. All use a minimum of scanning time, and the scanning and computing procedures are easy to implement. The first, using the initial slope of the enhancement vs time curve, is subject to errors of 17-26% from failure of the signal to rise linearly with time, caused by decay of plasma concentration, filling of leakage space, T2 losses, and signal nonlinearity with 1/T1. The second, the early enhancement method, takes account of all nonlinearities, and its accuracy is limited only by lack of prior knowledge of the size of the leakage space; some iterative computation is required. For brain lesions the error is 11%, with an imaging time of 3-10 minutes. The third, the simplified early enhancement method, appropriate for retinal lesions, takes account of plasma decay only and requires simpler computation. The maximum error is 10%, with an imaging time of 12-45 minutes.