Biomedical subjects

J Wittenberg

Publications and source records attributed to J Wittenberg.

At least 73 records · Page 4Linked to original sources

PubMed1987

Ferrite-enhanced MR imaging of hepatic lymphoma: an experimental study in rats.

The purpose of this investigation was to define the potential of unenhanced and ferrite-enhanced MR to detect hepatic lymphoma. Rats were implanted with diffuse and focal hepatic lymphoma. Both in vitro measurements of relaxation times and in vivo MR imaging of normal liver and of diffuse and focal hepatic lymphoma were compared. Diffuse infiltrative hepatic lymphoma showed increased T1 (45%) and T2 (41%) relaxation times in vitro, but could not be distinguished from normal control livers on in vivo spin echo (SE) images with a repetition time of 500 msec and an echo time of 30 msec (SE 500/30) or SE 1500/60 images. Focal hepatic lymphoma showed increased T1 (185%) and T2 (115%) relaxation times relative to normal liver tissue. Focal hepatic lymphoma was undetectable on unenhanced SE 500/30 MR images (contrast-to-noise ratio, C/N = 0.4) and was slightly hyperintense on SE 1500/60 images (C/N = 1.1). Ferrite (50 mumol Fe/kg) was administered to improve tissue contrast. In normal control animals, T2 of liver in vitro decreased from 29.3 +/- 3.3 msec to 11.1 +/- 1.2 msec, and image signal-to-noise ratio (S/N) of liver in vivo decreased from 16.1 +/- 2.4 to 2.8 +/- 0.3 (p less than .005). Ferrite-enhanced diffuse hepatic lymphoma showed in vitro T2 values and in vivo MR image S/N values indistinguishable from those of normal control animals. The T2 of focal hepatic lymphoma was essentially unaltered by ferrite. On SE 500/30 images, focal hepatic lymphoma became readily detectable, quantitated by a 35-fold increase in tumor-liver C/N. We conclude that clinical studies are warranted to determine the value of ferrite enhanced MR as a technique for the enhanced detection of focal hepatic lymphoma.

Animals↗

PubMed1986

Percutaneous drainage of diverticular abscess. An adjunct to surgical therapy.

We undertook this study to determine whether a computed tomography-guided, percutaneous preoperative drainage of a peridiverticular abscess can safely allow a one-stage procedure in patients requiring surgery for acute diverticulitis. In 17 patients evaluated prospectively by computed tomography, thin-needle aspiration demonstrated purulent fluid collection in 11 patients. Percutaneous catheter drainage was undertaken in eight patients. In the three remaining patients, the abscess was either too small to warrant drainage or no safe access route was present. Seven of eight patients had a single-stage resection within one to three weeks of percutaneous catheter drainage. There were no complications. Our studies suggest that a combined radiological-surgical approach has the potential to reduce morbidity and hospital costs without increasing mortality in the management of perforated colon diverticulitis with associated abscess formation.

Abscess↗

PubMed1986

Pancreatic necrosis: CT manifestations.

Pancreatic necrosis is a potential sequela of acute pancreatitis, which pathologically represents a collection of devitalized tissue. Appropriate therapeutic planning requires definition of this irreversibly damaged gland, the presence of which is not consistently diagnosed on the basis of clinical and laboratory data. Over an 18-month period, 22 patients with pancreatic necrosis were studied by one or more computed tomographic (CT) examinations. Retrospective analysis showed the findings to vary with the developmental stage of the necrotizing process. During the acute phase, there was considerable morphologic overlap of necrosis and pancreatic phlegmon. Typical findings were seen in the subacute and chronic stages and included diffuse enlargement of the gland with largely decreased central density. A thick, smooth surrounding rim produced a characteristic saclike configuration. CT-guided aspiration for culture material was performed in four patients with suspected superinfection. Negative gram stain and culture results in two patients allowed surgery to be performed on a more elective basis.

Acute Disease↗

PubMed1986

Liver metastases: detection by phase-contrast MR imaging.

Forty patients with biopsy-proved metastatic liver cancers were studied by magnetic resonance (MR) imaging using one or more conventional (in-phase) pulse sequences and a corresponding phase-contrast (opposed-phase) pulse sequence. Pulse-sequence performance was quantitated by measuring signal-difference-to-noise (SD/N) ratios between cancerous tissue and liver. The SD/N performance of T2-weighted spin-echo (SE) pulse sequences improved when used with the phase-contrast technique. SE 2,000/30 opposed-phase images showed improved (P less than .001) SD/N in 72% of patients over in-phase images. The SD/N of T1-weighted SE or inversion recovery pulse sequences deteriorated when used with the phase-contrast technique. Changes in measured SD/N correlated well with image appearance and actual lesion detectability in individual cases. Phase-contrast imaging should be employed routinely when T2-weighted SE pulse sequences are relied on to detect liver cancer.

Humans↗

PubMed1986

Drainage of pelvic abscesses through the greater sciatic foramen.

A computed tomographic (CT) guided transgluteal approach through the greater sciatic foramen was used to drain pelvic abscesses and fluid collections in 21 patients. Ideal catheter placement should traverse the lower portion of the greater sciatic foramen at the level of the sacrospinous ligament. This avoids the vascular and neural elements that are located slightly cephalad at the level of the piriformis muscle. Percutaneous drainage through this approach was successful in avoiding surgery in 17 patients (81%). Pain was the most common complication and was generally associated with a more cephalad approach, transgressing the piriformis and the sacral plexus. CT-guided percutaneous drainage of pelvic abscesses through the greater sciatic foramen should be used when the more standard transperitoneal approach is not possible.

Abscess↗

PubMed1986

Detection of hepatic metastases: analysis of pulse sequence performance in MR imaging.

Forty-three patients with liver metastases were imaged using 14 different pulse sequences (average, 7.5 sequences per patient) to allow direct comparison of their performance. "T2-weighted" spin-echo (SE) images, "T1-weighted" inversion recovery (IR) images, and "T1-weighted" SE images were obtained using a wide range of timing parameters. Pulse sequence performance was quantitated by measuring liver signal-to-noise (S/N) ratios and cancer-liver signal difference-to-noise (SD/N) ratios. Data were standardized to reflect a constant imaging time of 9 minutes for all pulse sequences. The SE 2,000/120 (TR [repetition time]/TE [echo time]) sequence resulted in the greatest SD/N ratio of the T2-weighted SE sequences but also yielded the low S/N ratios, poor anatomic resolution, and motion artifacts common to all T2-weighted SE images. IR sequence images were also sensitive to motion artifacts because of the use of a long TR (1,500 msec). Short TR/TE T1-weighted SE sequences (SE 260/18) had the greatest SD/N ratio (P less than .05), S/N ratio, and anatomic resolution. Furthermore, extensive signal averaging appears to be a powerful solution to all types of motion artifacts in the abdomen.

Adenocarcinoma↗

PubMed1986

Rapid MR imaging with suspended respiration: clinical application in the liver.

The authors demonstrate that it is possible to obtain highly T1-weighted images of the abdomen using a suspended respiration partial saturation (SRPS) method in a breath-holding interval. T2*-weighted images, which reflect tissue T2 as well as variations in the static magnetic field, can also be rapidly obtained. The authors studied five healthy subjects and 19 patients with a variety of liver abnormalities, including benign and malignant hepatic neoplasms, fatty liver infiltration, ascites, and hematoma. On T1-weighted multisection acquisitions, the entire liver can be screened for mass lesions in a single 20-second breath-holding interval. Phase-contrast SRPS images are sensitive to fatty infiltration of the liver. SRPS images are more sensitive to variations in magnetic susceptibility than spin-echo images are, which has been proved to be of value in the detection of hemorrhage. With continued pulse sequence development and clinical study, this method has the potential to become the method of choice for evaluation of the upper abdomen.

Adult↗

PubMed1986

MR-guided aspiration biopsy: needle design and clinical trials.

Nonferrous needles of pure brass, titanium, or copper, and ferrous needles of different alloys of stainless steel were analyzed for the size, area, and distribution of the image artifact created when the needles were placed in a 0.6-T magnet. Results demonstrated that a stainless steel prototype needle (type 316) would be visible on magnetic resonance images and would provide an artifact similar to that seen in computed tomographic-guided biopsies. Further testing of this prototype included assessment of the effect on the artifact when changes were made in annealing properties, gauge, length, needle-tip geometry, pulse sequence, and orientation relative to the magnetic field. To date, three human liver biopsies have been successfully and safely performed using a stainless steel type 316 needle.

Aged↗

PubMed1986

Preoperative evaluation of abdominal aortic aneurysms by computed tomography.

A prospective, preoperative study was conducted of 50 electively repaired abdominal aortic aneurysms comparing the CT and angiographic findings with those described at surgery. CT demonstrated all 50 aneurysms and correctly identified their proximal extent in relation to the takeoff of the renal arteries in 47 patients (94%), while angiography detected 48 aneurysms (96%) and their correct relation to the renal arteries in all (100%). CT correctly identified 40 (98%) of 41 patients with two renal arteries, but only two (29%) of seven with three and none of two patients with four arteries. Common iliac artery involvement or lack thereof was accurately predicted in 42 (84%) of the 50 patients and internal iliac artery aneurysms found in one (33%) of three patients. It was concluded that CT is not sufficiently accurate for documenting location and patency of the renal arteries to allow its routine substitution for angiography in patients undergoing preoperative assessment of abdominal aortic aneurysms.

Aged↗

PubMed1986

Staging rectal cancer by MR and CT.

Sixteen patients with known rectal cancer were evaluated and staged with CT and MR, and at surgery. Detailed evaluation of the pathologic specimens was performed and correlated with CT and MR to determine the accuracy of staging. Most of the cases were advanced stages, and both CT and MR were equally effective in staging. Prone positioning using an air-distension technique was equally important for CT and MR examinations. Because of a positive contrast material (iodine), adequate CT examinations could be performed without prior bowel preparation; however, bowel cleansing was necessary for MR examinations. Both techniques could identify the primary tumor and invasion into perirectal fat and local organs. Neither CT nor MR were able to assess the extent of bowel-wall infiltration or tumor spread to normal size perirectal lymph nodes.

Air↗

PubMed1986

Dynamic spin-echo MRI of liver cancer using Gadolinium-DTPA: animal investigation.

An animal model of liver cancer was used to demonstrate that with a fast MRI technique, Gadolinium-DTPA increases tumor-liver contrast. A spin-echo pulse sequence with short repetition (TR) and echo-delay (TE) times (TR 250/TE 15/Excitations 1) has a scan time of 0.6 min, which allows early dynamic postcontrast infusion imaging. This is necessary to capture peak compartmental differences when an extracellular contrast agent such as Gadolinium-DTPA is used. This short TR/short TE pulse sequence also increases T1-dependent tissue contrast over the traditional (inversion recovery or spin echo) T1-weighted pulse sequences. Our studies suggest a significant potential for improved detection of liver metastases with Gadolinium-DTPA-enhanced liver MRI.

Adenocarcinoma↗

PubMed1985

The bile ducts after a fatty meal: further sonographic observations.

The sonographic appearance of the response of the common hepatic duct to physiologic stimulation by a fatty meal was assessed in 131 patients referred because of right upper quadrant symptoms or abnormal liver chemical studies. In the determination of the presence or absence of biliary obstruction, the sensitivity of the examination was 84%, the accuracy of a positive test was 84%, and the accuracy of a negative test was 93%. This test proved helpful in several circumstances: equivocal duct caliber (6-10 mm); abnormal caliber (6-14 mm) with normal laboratory values; normal caliber duct with abnormal laboratory values; persistent question of cholelithiasis or asymptomatic pancreatic duct dilatation. Measurements of bile duct caliber alone may be insufficient to ascertain the presence of bile duct obstruction and fatty meal stimulation significantly improves diagnostic accuracy.

Bile Ducts↗

PubMed1985

Lesser sac abscesses and fluid collections: drainage by transhepatic approach.

Twelve abscesses and fluid collections in the lesser peritoneal sac were drained percutaneously using an access route across the intervening liver. This rather unusual access was chosen when other approaches were contraindicated because of surrounding colon, stomach, or spleen. All collections were drained successfully, and no specific complications such as hemorrhage, bile leak, or liver abscess occurred. Placement of an abscess drainage catheter should be done through the peripheral portion of the liver if possible. The technique offers a new, safe approach to percutaneous drainage of hitherto inaccessible collections.

Abscess↗

PubMed1985

Surface coil MR imaging of abdominal viscera. Part II. The adrenal glands.

Magnetic resonance (MR) imaging of the adrenal glands with a prototype surface coil was compared with conventional body coil images in five healthy volunteers and 15 patients with adrenal disease. The spectrum of abnormalities included five nonfunctioning cortical adenomas, of which two were in hyperplastic glands, four adrenal metastases, three pheochromocytomas, a functioning adenoma, a myelolipoma, and a partially calcified, cystic adrenal mass. In both body and surface coil images, anatomic detail was superior on T1-weighted images compared with T2-weighted images obtained with identical imaging time because of decreased motion artifact and superior contrast. In the T1-weighted studies, high-resolution surface coil images showed a threefold improvement in signal-to-noise ratio (SNR) over body coil images, which was manifest by better intrinsic resolution of small adrenal lesions and clearer definition of the extrinsic relationships of large masses to nearby organs. In addition, inferior vena caval invasion by two right adrenal metastases was better demonstrated using the surface coil than body coil MR or computed tomography (CT). Limitations of surface coil imaging include restriction in the field of view to a single gland and additional time required for patient positioning. Since the sensitivity of surface coils diminishes with depth, gains in SNR were limited in large patients with deeper adrenal glands. Despite these limitations, dramatic improvements in SNR and anatomic resolution indicate that surface coil MR imaging will be competitive with CT for examining the adrenal glands.

Adrenal Gland Diseases↗

PubMed1985

Surface coil MR imaging of abdominal viscera. Part III. The pancreas.

Eight healthy volunteers and 11 patients with pancreatic abnormalities were studied using a conventional body coil and a prototype magnetic resonance (MR) surface coil. Final pathologic diagnoses included carcinoma of the head (six), body (one), and tail of the pancreas (two) and chronic pancreatitis (two). In surface coil images of the volunteers, the body and tail of the pancreas was visualized in all cases but one, and the pancreatic duct was seen in five of eight cases. In-plane spatial resolution of 0.9 X 0.9 mm and 5-mm section thickness was obtained. At the same time, pancreatic surface coil images had a twofold improvement in the signal-to-noise ratio (SNR) compared with body coil images. T1-weighted spin-echo images gave greater SNR, reduced motion artifacts, provided superior anatomic detail, and offered more diagnostic information than comparable T2-weighted images. Significant abnormalities detected only by surface coil imaging included a small tumor surrounded by reactive edema and periglandular tumor invasion. This study demonstrates that surface coil imaging of the pancreas not only is feasible but provides an improved method for examining the pancreas by MR.

Adult↗

PubMed1985

Comparison of sonography and plain films in evaluation of the acute abdomen.

In 95 patients with acute abdominal pain seen in the emergency ward of a large urban teaching hospital, real-time sonography was performed in conjunction with a plain film of the abdomen in order to detect what, if any, added information was provided by the sonographic examination. In 20 patients (21%) the sonogram contributed important diagnostic information not provided by the plain film of the abdomen. Most of these patients had pathology referable to the biliary tract (14 of 20). In 28 patients (30%), the sonogram confirmed the diagnosis by abdominal film. In 39 (41%) the sonogram added no relevant information, and in three (3%) it was deleterious. In five (5%) the plain film provided more information than the sonogram.

Abdomen, Acute↗

PubMed1985

Presacral masses after abdominoperineal resection for colorectal carcinoma: the need for needle biopsy.

Computed tomographic(CT)-guided biopsy of presacral masses after abdominoperineal resection for colorectal carcinoma was performed in 28 patients, using a transgluteal approach. The masses were divided into three groups according to their morphologic appearance: solid mass, mass with central low-density area, and gas-containing mass. Of 19 patients with a homogeneous solid mass, 15 had biopsy-proven recurrent adenocarcinoma. In the other nine patients, who had low-density masses with or without gas, it was not possible to offer a diagnosis on the basis of the CT appearance alone. In these cases, needle biopsy disclosed various entities, including recurrent tumor, abscess, and posttreatment necrosis. There was only one complication, transient hematuria. CT-guided needle biopsy of presacral masses after abdominoperineal resection is a simple, relatively safe, and valuable diagnostic technique.

Adenocarcinoma↗

PubMed1985

Percutaneous drainage of pyogenic liver abscesses.

This report summarizes the results of percutaneous catheter drainage in 23 cases of primary or secondary pyogenic liver abscess. The overall success rate was 76%. Only three (60%) of five cases of secondary abscess (infected hematoma or infected tumor) were cured with catheter drainage, but 11 (91%) of the last 12 primary pyogenic abscesses were drained successfully. Six patients with abscesses of less than 4 cm in diameter required catheter drainage for less than 72 hr. Although six abscesses in the series appeared septated or multiloculated, only one required more than a single catheter for curative drainage. Diagnostic and technical considerations for successful drainage of hepatic abscesses are discussed. The differential diagnosis includes echinococcal disease and hepatic amebiasis. Therapeutically, specific measures should be taken to ensure proper catheter position to prevent contamination of the subphrenic, perihepatic, and pleural spaces. Percutaneous catheter drainage should be attempted as a first choice of treatment in all pyogenic hepatic abscesses.

Diagnosis, Differential↗