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The purpose of this study was to evaluate the safety and efficacy of a manganese chloride-based oral magnetic resonance (MR) contrast agent during a Phase III multisite clinical trial. Two hundred seventeen patients were enrolled who were already scheduled for MRI of the abdomen and/or pelvis. In this group of patients, it was postulated that the use of an oral agent would better allow discrimination of pathology from bowel. Patients with known gastrointestinal pathology including peptic ulcer disease, inflammatory bowel disease, obstruction, or perforation were excluded to minimize confounding variables that could affect the safety assessment. Of these 217 patients, 18 received up to 900 mL of placebo, and 199 patients were given up to 900 mL of a manganese chloride-based oral contrast agent, LumenHance (Bracco Diagnostics, Inc.). Safety was determined by comparing pre- and post-dose physical examinations, vital signs, and laboratory examinations and by documenting adverse events. Efficacy was assessed by unblinded site investigators and two blinded reviewers who compared pre- and post-dose T1- and T2-weighted MRI scans of the abdomen and/or pelvis. In 111 (57%) of the 195 cases evaluated for efficacy by site investigators (unblinded readers), MRI after LumenHance provided additional diagnostic information. Increased information was found by two blinded readers in 52% and 51% of patients, respectively. In 44/195 cases (23%) unblinded readers felt the additional information would have changed patient diagnosis and in 50 patients (26%), it would have changed management and/or therapy. Potential changes in patient diagnosis or management/therapy were seen by the two blinded readers in 8-20% of patients. No clinically significant post-dose laboratory changes were seen. Forty-eight patients (24%) receiving LumenHance and four patients (22%) receiving placebo experienced one or more adverse events. Gastrointestinal tract side effects were most common, seen in 29 (15%) of LumenHance patients and in 3 (17%) of the placebo patients. LumenHance is a safe and efficacious oral gastrointestinal contrast agent for MRI of the abdomen and pelvis.

Objective: The purpose of this study was to compare liver signal-to-noise ratio (SNR), lesion SNR, and lesion-liver contrast-to-noise-ratio (CNR) in patients with malignant liver lesions after the administration of a standard dose (0.1 mmol/kg of body weight) or a triple dose (0.3 mmol/kg) of a gadolinium chelate (gadoteridol). We hypothesized that the higher dose would produce a higher lesion-liver CNR and therefore increase the conspicuity of hepatic lesions., Materials and Methods: A total of 85 patients with malignant hepatic masses (61 metastases, 22 hepatocellular carcinomas, and two lymphomas) proved by histologic or follow-up studies underwent MR imaging at 1.5 T. T1-weighted spin-echo imaging and gradient-echo imaging were done before and within 1 min after (gradient echo) as well as 5 (spin echo) and 15 (spin echo) min after the injection of 0.1 or 0.3 mmol of gadoteridol per kg, randomized before the start of the study (39 patients received the standard dose, and 46 received the triple dose). The signal intensities of the liver and lesions and the SD of background noise were measured by use of regions of interest to calculate the SNR of the liver and malignant lesions and the lesion-liver CNR., Results: The lesion-liver CNR was increased significantly at 5 and 15 min after the administration of gadoteridol. No significant differences in the liver SNR, lesion SNR, and lesion-liver CNR (after 1 min: standard dose, -5 +/- 8, and triple dose, -4 +/- 14; after 5 min: standard dose, -1 +/- 5, and triple dose, 2 +/- 8; and after 15 min: standard dose, 1 +/- 5, and triple dose, 6 +/- 20) were found between the doses at all time points., Conclusion: Triple-dose gadoteridol does not improve the lesion-liver contrast of malignant hepatic lesions over that provided by the standard dose and is not warranted for liver MR imaging.

To determine the safety of a manganese chloride-based oral magnetic resonance (MR) contrast agent and the ideal concentration of the agent for marking in three different anatomic sites (stomach, middle of the small bowel, and ileocecal region), six healthy volunteers were evaluated before and after administration of 900 mL of three different concentrations of the contrast agent. Images were evaluated subjectively and objectively. No adverse events were noted. There was a minimal rise in manganese blood levels at 6 hours after administration, with a return to baseline at 24 hours. The imaging data demonstrated good-to-excellent bowel marking on T1-weighted images at all three concentrations. However, on T2-weighted images, the 40 mg Mn+2/L concentration provided improved hypointense bowel marking relative to the 20 mg/L concentration. Little difference was seen between the 40 and 60 mg/L concentrations. Fast T1- and T2-weighted sequences provided superior image quality to that of conventional spin-echo sequences.

The enhancement characteristics of the liver and spleen produced by a hepatocyte-specific magnetic resonance imaging agent, an arabinogalactan-coated ultrasmall superparamagnetic iron oxide derivative, BMS 180550, were evaluated. Both heavily T1- and T2-weighted sequences were used. Imaging was performed in the farm pig model, as a function of contrast agent concentration (5, 10, and 20 mumol of iron per kilogram) and delay (immediate, 0.5, 2.5, 5.0, 7.5, and 9.0 hours) after bolus injection of BMS 180550. BMS 180550 provided excellent contrast enhancement characteristics by producing marked positive enhancement with T1-weighted sequences and marked negative enhancement with T2-weighted sequences. The T1-weighted enhancement immediately after contrast agent injection was of greater magnitude in the spleen (329% +/- 83) than in the liver (66% +/- 16). Postcontrast negative enhancement with T2-weighted sequences was largely hepatocyte specific at 5 and 10 mumol/kg but was also seen within the spleen at 20 mumol/kg. The authors discuss the possible mechanisms that produce these changes and conclude that 10 mumol/kg BMS 180550 is near the optimum dose for maximizing the enhancement properties of this agent with all sequences in the farm pig.

Purpose: To evaluate prospectively the diagnostic accuracy of non-enhanced and gadolinium-enhanced magnetic resonance (MR) imaging in characterization of hepatic lesions., Materials and Methods: Fifty-five patients with benign and 52 patients with malignant focal liver lesions underwent examination at 1.5 T that comprised nonenhanced and dynamic contrast material-enhanced images. Four experienced radiologists independently read the different sets of images without and with knowledge of clinical history., Results: Receiver operating characteristic analysis showed that dynamic contrast-enhanced MR imaging added information to nonenhanced MR studies and thereby improved distinction between benign and malignant lesions (P < .05). Knowledge of clinical data further improved lesion characterization with nonenhanced and combined nonenhanced and contrast-enhanced MR imaging (P < .05)., Conclusion: Dynamic contrast-enhanced MR imaging is a useful adjunct for characterization of hepatic lesions. Knowledge of clinical history still has a decisive effect on interpretation of MR images of the liver.

Purpose: Magnetic resonance (MR) images were correlated with results of fine-needle aspiration (FNA) to determine the role of MR imaging in evaluating hepatic neoplasms treated with percutaneous ethanol ablation therapy (PEAT)., Materials and Methods: Contrast material-enhanced and unenhanced MR images were obtained in 11 patients with hepatic neoplasms before PEAT (13 studies) and at intervals after PEAT (25 studies). FNA was performed at each follow-up visit., Results: After PEAT, the MR appearance of the lesions was extremely variable. Also, the signal characteristics of most lesions did not change significantly with any sequence over time. Of eight lesions that demonstrated contrast enhancement before therapy, four demonstrated persistent enhancement and four showed loss of enhancement. Six of these lesions had no viable tumor at FNA. T2-weighted sequences most often showed mixed signal intensity regardless of T2-weighted imaging appearance before therapy., Conclusion: The MR appearance of PEAT-treated hepatic lesions is not a reliable indicator of residual or recurrent tumor.

Fifty-eight patients suspected of having focal hepatic disease were studied prior to and following the intravenous administration of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate) (DPDP), a hepatobiliary magnetic resonance (MR) contrast agent. Four doses (3, 5, 8, or 10 mumol/kg) of Mn-DPDP were used to test the hypothesis that Mn-DPDP-enhanced MR imaging would display enhancement in tumors of hepatocellular origin. A total of 203 lesions were evaluated. Histologic proof was available in 32 cases, and in 26 cases lesions were evaluated on the basis of characteristic imaging findings. Statistical calculations for distinction of tumors of hepatocellular origin yielded a sensitivity of 100%, a specificity of 92.0%, an accuracy of 93.6%, a positive predictive value of 75.9%, and a negative predictive value of 100%. The authors conclude that the presence and patterns of enhancement at Mn-DPDP-enhanced MR imaging permit reliable distinction between hepatocellular and nonhepatocellular tumors.

BMS 180549 (previously AMI-227), an ultrasmall superparamagnetic iron particulate agent, was investigated to determine its utility as a contrast agent on T1-weighted, as well as T2-weighted sequences, as a function of route of administration, (intravenous versus selective arterial) and concentration. Twelve farm pigs were divided into three groups of four each by route of administration (intravenous, selective superior mesenteric, or selective hepatic arterial injection). 10 mumol/kg and 20 mumol/kg dosages were given and evaluated both immediately after and 20-24 hr after contrast infusion, using both spin-echo and gradient-echo T1 and T2-weighted sequences. Significant postcontrast liver and spleen enhancement was noted at both concentrations, regardless of route of administration on both T1- and T2-weighted sequences. The earliest postcontrast T1-weighted sequence obtained during the 1-3 min interval following IV administration of high dose (20 mumol/kg) contrast demonstrated an average of +42.8% liver and +249.0% spleen enhancement; 24 hr later this decreased to 0 and 7.2%, respectively. The earliest postcontrast T2-weighted sequence obtained during the 8-17 min interval post high-dose IV contrast showed an average of -75.8% decrease in liver and -28.7% decrease in spleen signal intensity; 24 hr later the magnitude of these changes diminished to -33.1% and +2.5%, respectively. No significant difference was noted in liver or spleen enhancement, regardless of route of contrast administration (intravenous versus intraarterial).

Ninety-six patients with known or suspected focal hepatic disease were evaluated in a multiinstitutional study of manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'bis(phosphate) (DPDP) as a hepatic-specific contrast agent for magnetic resonance (MR) imaging. The patients were divided into four dose groups, receiving 3, 5, 8, or 10 mol/kg of Mn-DPDP. Half of the patients in each dose group received Mn-DPDP as an intravenous bolus (0.25 mL/sec) and the other half as an infusion (1 mL/min). Patients were evaluated with T1-weighted imaging parameters. No serious side effects were noted. In 76 patients, both Mn-DPDP-enhanced and nonenhanced T1-weighted images depicted the same number of lesions, but one additional lesion was depicted with enhanced imaging in 12 patients, two additional lesions in three patients, and three additional lesions in three patients. Enhanced, T1-weighted images depicted no more lesions than nonenhanced, T2-weighted images in 77 patients, but one more lesion was depicted in nine patients, two more lesions in two patients, three more lesions in one patient, and four more lesions in one patient.

We used an animal model to investigate the hepatic enhancement characteristics of manganese dipyridoxyl diphosphate (MnDPDP) related to time, dose, and pulse sequence. The contrast doses selected were in the human tolerance range. Using an SE 300/15 pulse sequence, maximum mean hepatic enhancement of 45% (8 mumols/kg) and 58% (12 mumols/kg) over baseline was seen during a plateau maintained between 5 and 50 minutes postinjection in the 8 mumols/kg group, and between 10 and 90 minutes in the 12 mumols/kg group. This plateau was followed by a very gradual decline in hepatic enhancement. Using either 4 or 8 mumols/kg, there was a significant increase in postcontrast hepatic intensity on all relatively T1-weighted pulse sequences (spin echo [SE] 300/15, inversion recovery [IR] 1400/20/400, gradient echo [GE] 47/13/80 degrees, and GE 60/20/30 degrees) except GE 47/13/80 degrees at 4 mumols/kg. At 8 mumols/kg there was superior enhancement, with IR 1400/20/400 and SE 300/15, but at 4 mumols/kg there was no consistently superior sequence. None of the relatively T2-weighted pulse sequences (SE 2000/50, SE 2000/100, or GE 100/30/20 degrees) demonstrated a significant change in hepatic intensity using either dose of contrast. The data suggest that the best combination of dose, pulse sequence, and time for hepatic imaging with MnDPDP is 8 mumols/kg using heavily T1-weighted sequences 5 to 60 minutes following contrast administration.

Sixteen MR studies performed in four patients who had undergone combined pancreatic and renal transplantation were reviewed retrospectively to determine if dynamic gadopentetate dimeglumine-enhanced gradient-echo imaging is useful in the early diagnosis of pancreatic transplant rejection. The MR studies were performed between 3 days and 6 months after transplantation and consisted of T1- and T2-weighted spin-echo images as well as a gradient-echo image prior to administration of an IV bolus of gadopentetate dimeglumine (0.1 mmol/kg). After injection of gadopentetate dimeglumine, a static dynamic gradient-echo scan was obtained. Signal-intensity measurements were determined for each of the gradient-echo images and used to generate an enhancement curve. Because T2 values have previously been used as an objective indicator of rejection, the mean T2 of each pancreatic transplant was calculated also. The MR results were compared with clinical and laboratory data and/or percutaneous biopsy results. In six studies of normally functioning pancreatic allografts, the percent enhancement during the first minute of the enhancement curve was 98 +/- 23% (1 SD). In six episodes of acute dysfunction (rejection or infarction), the first-minute enhancement was 42 +/- 20%. In four cases of dysfunction, the finding of an abnormal enhancement curve preceded a significant drop in urinary amylase by 1-4 days. The calculated T2 value was prolonged in only two cases in which biopsy-proved pancreatic infarction had occurred. No prolongation of T2 was evident in four cases of rejection alone. These results suggest that mean T2 calculation at 1.5 T may not be a reliable indicator of pancreatic transplant rejection, but that gadopentetate dimeglumine-enhanced gradient-echo MR imaging of the pancreatic transplant may be a reliable early indicator of pancreatic transplant dysfunction.

A prospective multi-institutional study was performed to compare the sensitivity of computed tomography (CT) and high-field magnetic resonance (MR) imaging (1.5T) in the detection of hepatic metastases. T1-weighted and 72-weighted spin-echo (SE) MR images were compared with noncontrast, dynamic, and delayed CT. Sixty-nine oncology patients were studied. Noncontrast CT showed an overall sensitivity of 57%, dynamic CT 71%, delayed CT 72%, T1-weighted SE MR 47%, and T2-weighted SE MR 78%. Although there was no statistically significant (p less than 0.05) difference among dynamic CT, delayed CT, and T2-weighted SE MR, these three methods were significantly more sensitive (p less than 0.005) than noncontrast CT or T1-weighted SE MR. T2-weighted SE MR was significantly more sensitive (p less than 0.006) than CT or T1-weighted SE MR in the detection of small (less than 1 cm) lesions. CT was more sensitive in the detection of extrahepatic disease. These data confirm the superiority of T2-weighted SE over T1-weighted SE pulse sequences at 1.5T.

Gadolinium (Gd)-DTPA was evaluated as a contrast agent for magnetic resonance (MR) imaging of the pancreas at 1.5T. Twenty-five patients were imaged with identical gradient-echo (GE) (TR 47, TE 13, 80 degree pulse angle) and spin-echo (SE) (TR 300, TE 15) MR sequences prior to and following an intravenous bolus of 0.1 mmol/kg Gd-DTPA. Marked pancreatic enhancement was demonstrated on dynamic sequential breath-hold GE images obtained immediately following the Gd-DTPA bolus (116% mean enhancement over pre-Gd-DTPA images). Enhancement decreased but persisted on the SE images obtained approximately 5 and 15 min following the Gd-DTPA bolus (65 and 60% mean enhancement, respectively). Five of the patients had a pancreatic mass. In these five patients, the enhancement of pancreatic tissue resulted in improved conspicuity of the mass. These initial results suggest that pancreatic enhancement occurs following an intravenous bolus of Gd-DTPA and has the potential to improve MR visualization of pancreatic masses.

The change in relative signal intensity of normal adrenal glands in 31 patients was evaluated following bolus administration of 0.1 mmol/kg of gadolinium diethylenetriamine pentacetic acid (Gd-DTPA). A marked increase in relative intensity of greater than 300% was observed within 2.5 min following contrast administration upon comparison of pre- and postcontrast T1-weighted gradient-echo images (TR = 47 msec, TE = 13 msec, pulse angle 80 degrees). Significantly elevated relative intensities of 55% and 44% persisted on postcontrast T1-weighted spin-echo images obtained at further delay times averaging 8 and 20 min, respectively, when compared to the identical precontrast sequence.

With a recently described rat model technique for direct hepatic injection of tumor cells for imaging research, there were concerns that the injection itself might produce lesions detectable with magnetic resonance (MR) imaging, thereby producing false-positive results. To examine this possibility, the authors prospectively studied 14 Sprague-Dawley rats after direct hepatic injection of cells from a rat hepatoma cell line. The rats were imaged with a variety of pulse sequences before and after intravenous injection of the contrast agent manganese dipyridoxal diphosphate at a dose of 8 mumol/kg. No intrahepatic lesions could be detected with MR imaging during the first 6 days after direct hepatic injection of the tumor cells. Therefore, the direct injection technique should be accurate for evaluating various MR imaging sequences and contrast agents for early hepatic tumor detection.

The diagnostic efficacy of magnetic resonance (MR) and computed tomography (CT) for detection and quantification of hepatic iron was assessed in a series of patients under investigation for clinical or biochemical evidence of hepatic iron overload. Thirty patients underwent MR imaging (SE 30,60/1000 or SE 30,60/2000) at 0.5 Tesla with calculation of hepatic T2 and liver to paraspinous muscle signal intensity ratios. Twenty-nine patients also had measurement of hepatic attenuation on noncontrast CT images. Results of these imaging studies were correlated in all patients with quantitative iron determination from liver biopsy specimens. The best predictor of liver iron among parameters studied was the ratio of the signal intensities of liver and paraspinous muscle (L/M) on a SE 60/1000 sequence. Both MR using L/M ratios and CT were sensitive methods for detection of severe degrees of hepatic iron overload with 100% of patients with hepatic iron on biopsy greater than 600 micrograms/100 mg liver dry weight detected on the basis of L/M less than 0.6 or CT attenuation greater than 70 Hounsfield units (HU). The MR parameter, however, was more specific than CT (100 vs 50%) and showed a higher degree of correlation with quantitated hepatic iron from biopsy. T2 measurements showed poor correlation with hepatic iron, due to difficulty in obtaining precise T2 measurements in vivo when the signal intensity is low. None of the parameters utilized was sensitive for detecting mild or moderate degrees of hepatic iron overload. We conclude that MR and CT are sensitive techniques for noninvasive detection of severe hepatic iron overload, with MR providing greater specificity than CT.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic MRI has become a useful imaging modality in recent years. As with all diagnostic imaging, the scanning techniques available for hepatic MRI are manifold and complex. The article discusses these techniques and their practical applications. Contrast agents and the MR appearances of various pathologic hepatic entities are also reviewed.

Twenty-nine patients with known or suspected malignancy were studied with identical T1-weighted (spin echo [SE] and inversion recovery [IR]) and T2-weighted SE magnetic resonance (MR) imaging at 0.5 and 1.5 T to evaluate the relative sensitivities of these sequences for detecting focal hepatic lesions. At 0.5 T, 98 lesions were detected with the IR sequence, 86 with the T1-weighted SE sequence, and 96 with the T2-weighted sequence. At 1.5 T, 93 lesions were detected with the IR sequence, 70 with the T1-weighted SE sequence, and 99 with the T2-weighted sequence. Although the lack of pathologic correlation precluded establishment of true sensitivity and specificity rates, data showed that magnetic field strength resulted in no significant difference for detecting focal hepatic lesions. No single sequence was shown to be significantly superior, although the T1-weighted SE sequence at 1.5 T was significantly inferior to the other sequences for detecting focal hepatic lesions. T1-weighted SE imaging at 0.5 T was significantly inferior to T1-weighted IR and T2-weighted imaging at both magnetic field strengths for detecting focal lesions in the left lobe of the liver. The authors conclude that T1-weighted IR and T2-weighted sequences alone will result in optimal MR imaging for the detection of focal hepatic lesions at 0.5 and 1.5 T.

A prospective multiinstitutional study was performed to compare the ability of dynamic sequential contrast material-enhanced computed tomography (CT), delayed contrast material-enhanced CT, and two T1-weighted magnetic resonance (MR) sequences (spin echo and inversion recovery) to demonstrate metastatic disease in the liver and abdomen in patients with cancer. All four techniques had comparable rates of hepatic lesion detection when compared individually or when the combined CT techniques were compared with the combined MR techniques. The sensitivity to hepatic disease was 96% (27 of 28 patients) for the combined MR techniques versus 93% (26 of 28 patients) for the combined CT techniques. However, CT was statistically superior in the detection of extrahepatic disease, with significant extrahepatic findings demonstrated by CT in only 12 of 59 patients (20%). For this reason, the authors continue to recommend CT in the initial screening of patients with cancer for upper abdominal metastatic disease.

The ability of a T1-weighted spin-echo magnetic resonance (MR) sequence to allow differentiation of benign from malignant adrenal masses at 0.5 T was investigated in 28 patients with 35 adrenal masses. All nine lesions with an adrenal mass-liver signal intensity ratio of 0.71 or less were metastases, and all 15 with a ratio of 0.78 or more were adenomas. Eleven masses (31%)--including six adenomas, three metastases, a pheochromocytoma, and a neuroblastoma--had ratios between these values. Nine of ten masses with adrenal mass-fat intensity ratios of 0.35 or less were metastases, and all 12 with ratios of 0.42 or more were benign. Eleven masses (31%), four malignant and one benign, had ratios between these values. The ratios for two masses could not be calculated due to lack of fat. The specificity of T1-weighted MR imaging in differentiating benign from malignant adrenal masses appears similar to that reported for T2-weighted imaging. However, significant overlap occurred, as has also been reported for T2-weighted imaging. While both imaging sequences may help distinguish benign from malignant adrenal masses in some cases, biopsy is still necessary when an accurate histologic diagnosis is essential.

Inability to demonstrate the renal corticomedullary junction (CMJ) on magnetic resonance (MR) images has been reported in connection with several medical renal diseases. T1-weighted spin echo pulse sequences have been advocated to demonstrate a signal intensity difference between cortex and medulla. This study was undertaken to determine which of several T1-weighted spin echo (SE) and gradient echo (GE) sequences are better for delineation of the CMJ. The MR studies were performed at 0.5 Tesla on 27 normal volunteers. Multi-slice axial images of both kidneys were obtained in all subjects at each of the following five pulse sequences: SE 250/20, SE 500/30, SE 900/30, and GE 300/15 with 80 degrees and 64 degrees flip angles. Contrast/noise ratios were calculated for the signal intensity differences between cortex and medulla; the average standardized contrast/noise ratios ranked as follows: GE 300/15/80 degrees = 3.01 +/- 0.74, GE 300/15/64 degrees = 2.72 +/- 0.74, SE 250/20 = 2.02 +/- 0.33, SE 500/30 = 1.96 +/- 0.51, and SE 900/30 = 1.71 +/- 0.39. In addition, the five sequences for each patient were randomized and the images were independently ranked for delineation of CMJ by three MR radiologists. The cumulative subjective ranking for all observers from best to worst is as follows: SE 500/30, GE 300/15/80 degrees, GE 300/15/64 degrees, SE 900/30, SE 250/20. Although better contrast/noise ratios are achieved with the GE sequences and the more T1-weighted SE sequences, as a practical matter this does not seem to be the only significant factor when compared with the visual image evaluation by independent observers.(ABSTRACT TRUNCATED AT 250 WORDS)

In an effort to determine whether T2 values of liver and muscle change with increasing field strength, 144 abdominal MR examinations were retrospectively evaluated. These patients were evaluated with a dual echo T2-weighted spin-echo sequence. Eighty-two of the examinations were performed at 0.5 Tesla and 72 at 1.5 Tesla (T). Eleven of the patients were evaluated with both MR systems with the same sequences. T2 values were also obtained from a Fe NH4(SO4)2 12H2O phantom. The T2 values of liver decreased from 57.8 +/- 11.3 at 0.5 T to 43.7 +/- 8.3 at 1.5 T. The T2 values of muscle decreased from 44.2 +/- 9 at 0.5 T to 35.4 +/- 7.2 at 1.5 T. Patients who were examined on both systems also demonstrated a decrease in both liver and muscle T2 values. For concentrations in the range of hepatic T2's, the phantom demonstrated a decrease in T2 values from 0.5 to 1.5 T ranging from 20.3 to 23.4%. All the T2 changes were statistically significant (p less than .05). The findings suggest that T2 values may depend on field strength, or may vary due to other hardware-related differences.

Magnetic resonance imaging of the liver was performed on 11 rabbits (3-5 kg) before and at 4, 5 and 6 hours after the intravenous administration of 0.3 mM/kg Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) to determine if hepatocytes exhibit delayed excretion of Gd-DTPA, similar to the delayed hepatic excretion of iodinated contrast agents. Imaging was performed at 0.5 Tesla in the axial plane using a spin echo sequence of TR/TE, 250/20 milliseconds. Precontrast and postcontrast intensity changes for liver and muscle were standardized and compared over time. The average percent of postcontrast enhancement for liver and muscle, respectively was: 30.6 +/- 9.5% and 17.3 +/- 17.0% immediately postcontrast; 9.7 +/- 13.6% and 1.6 +/- 13.8% at 4 hours; 9.6 +/- 7.8% and 4.3 +/- 13.2% at 5 hours; and 11.0 +/- 7.8% and 4.1 +/- 11.7% at 6 hours. We conclude that there is not significant hepatocyte excretion of Gd-DTPA at 4 to 6 hours postcontrast injection in rabbits and that this may not be an advantageous paramagnetic contrast strategy for focal hepatic lesion detection.

Eighteen patients with focal hepatic lesions were evaluated with two computed tomographic (CT) techniques including dynamic sequential bolus contrast CT and delayed contrast CT, and 3 magnetic resonance (MR) techniques including a spin echo pulse sequence with TE/TR of 21/310 msec and 2 fast field echo sequences using a TE/TR of 15/300 msec and 80 degrees flip angle (T1-weighted) and TE/TR of 15/500 msec and 10-20 degrees flip angle (T2-weighted). We concluded that CT, using delayed contrast and dynamic sequential bolus contrast techniques, was consistently superior to the 3 MR pulse sequences used on our imagers in terms of number of lesions detected, lesion-to-liver contrast, and quality of scan.

Forty-three patients with known primary or secondary neoplastic involvement of the liver underwent evaluation to determine the number, size, and location of focal lesions before possible tumor resection. Imaging studies included computed tomography (CT) during arterial portography (CTAP), delayed CT, and magnetic resonance (MR) imaging at various pulse sequences. Results of radiologic studies were compared with surgical and pathologic findings. In the combined group of surgical and nonsurgical patients, CTAP was significantly more sensitive (85%) than all other techniques except 1.5-T T2-weighted spin-echo imaging (64%). Combining the information from all MR pulse sequences yielded a cumulative sensitivity of 68%. Combining the information from two modalities yielded sensitivity of 96% for CTAP plus MR imaging, 85% for CTAP plus delayed CT, and 77% for delayed CT plus MR imaging. The authors conclude that when it is vital to know the precise number, size, and location of focal hepatic lesions before tumor resection, CTAP has the highest sensitivity, but MR imaging is an important adjuvant.