Magnetic resonance (MR) imaging methods with good spatial and contrast resolution are often too slow to follow the uptake of contrast agents with the desired temporal resolution. Imaging can be accelerated by skipping the acquisition of data normally taken with strong phase-encoding gradients, restricting acquisition to weak-gradient data only. If the usual procedure of substituting zeroes for the missing data is followed, blurring results. Substituting instead reference data taken before or well after contrast agent injection reduces this problem. Volunteer and patient images obtained by using such reference data show that imaging can be usefully accelerated severalfold. Cortical and medullary regions of interest and whole kidney regions were studied, and both gradient- and spin-echo images are shown. The method is believed to be compatible with other acceleration methods such as half-Fourier reconstruction and reading of more than one line of k space per excitation.

The purpose of our study was to determine the frequency of detection of small hepatic lesions ( 15 mm) in outpatients who had abdominal CT and to assess the significance of these lesions in the presence or absence of known malignant tumors. Contrastenhanced abdominal CT scans In 1454 patients were reviewed. In 254 patIents (17%), hepatic lesions 15 mm or smaller were detected. In 51% of these patients, lesions were judged benign on the basis of other imaging studies, biopsy results, or stability for at least 6 months as shown by CT. Lesions were judged malignant on the basis of progression seen on radiologic studies or biopsy in 22%. The other 27% of the patients had lesions that could not be classifled The majority of patients with small hepatic lesions (82%) were known to have a malignant tumor-in 51% of these patients, lesions were diagnosed as benign. No patient without a known malignant tumor had a small hepatic lesion that was determined to be malignant. Multiple small lesions were more likely to represent malignant disease than were single small lesions.We conclude that small hepatic lesions are common (seen in 17% of our patients), and that there is a high probability that hepatic lesions smaller than 15 mm are benign, even in patients known to have an extrahepatic malignant tumor.

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.

No abstract

This study measured cardiac output before and 1 or 2 yr after orthotopic liver transplantation in 23 patients. Cardiac output was measured by thermodilution before transplantation and by first-pass radionuclide angiocardiography at follow-up. Study patients were selected as those doing well clinically and by standard laboratory tests at 1-yr and 2-yr reevaluations with no evidence of rejection: six had mild recurrent hepatitis shown on biopsy samples. Hepatocyte function was normal at the time of the study as shown by galactose elimination capacity of 442 +/- 90 mg/min. Medications were cyclosporine and prednisone in all patients, azathioprine in 10 patients and a combination of antihypertensive therapy to maintain diastolic blood pressure less than 90 mm Hg in 20 patients. Mean (+/- S.D.) pretransplantation cardiac output was 9.1 +/- 3.1 L/min and remained elevated at 8.3 +/- 2.1 L/min 1 yr, and 9.6 +/- 2.6 L/min (n = 13) 2 yr after transplantation. A significant (p less than 0.001) correlation was found between pretransplant and follow-up cardiac output. End diastolic, end systolic and stroke volumes are all increased in a pattern similar to that seen in end-stage cirrhosis. These data show that the high cardiac output of the hyperdynamic state of advanced liver disease persists after liver transplantation. The mechanisms and consequences of this require further study.

The authors retrospectively studied 36 hepatic masses in 20 patients who underwent computed tomography during arterial portography (CTAP) and subsequent hepatic tumor resection. The authors used the right main and left main portal veins as landmarks for the transverse scissura, along with the hepatic veins, the gallbladder fossa, and the umbilical fissure to blindly predict the segmental location of each tumor confirmed at surgery. The right main and left main portal veins were found to be consistently near the middle sections through the liver. CTAP findings and surgical descriptions agreed on the primary segmental location of 33 of 36 focal lesions (92%) but disagreed on the extent of 11 of 36 lesions (31%). Further review of the CTAP scans of the 11 lesions revealed that the extent of the lesion was more correctly described at surgery in six masses and at CTAP in four masses; in one lesion, opposite margins of the same mass were correctly described at both surgery and CTAP. Since it may be difficult or impossible to localize deep hepatic lesions intraoperatively by means of palpation or inspection, CTAP is a helpful preoperative tool for determining the segmental location of lesions and for planning the surgical approach.

No abstract

No abstract