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Biomedical subjects

R F Mattrey

Publications and source records attributed to R F Mattrey.

At least 55 records · Page 3Linked to original sources
PubMed1991

Potential role of PFOB enhanced sonography of the kidney. II. Detection of partial infarction.

Aside from its ability to assess flow velocity within vessels, color Doppler and gray-scale sonography cannot distinguish perfused from non-perfused tissues. In this study we evaluated whether Perfluorooctylbromide (PFOB), a sonographic contrast agent given i.v., could aid sonography with this recognition. Partial renal infarction was produced by a 1 mm bead embolized in the right, the left, or both renal arteries of 20 normal rabbits. The sonographer, unaware of rabbit assignment, attempted to diagnose the infarct 24 hours later. All 20 rabbits were studied with gray-scale and color Doppler sonography, 10 before and after PFOB and 10 only after PFOB. Angiography and post-mortem examination were done for confirmation. Of the 20 kidneys evaluated before PFOB, the sonographer was unable to diagnose the 10 partial infarctions. Color Doppler identified five of the ten infarcted kidneys, but accurately localized the infarction in only two. Of the 40 kidneys evaluated after PFOB infusion, 20 scanned before and 20 scanned only after PFOB, all 20 partial infarctions were accurately diagnosed with both gray-scale and color Doppler. PFOB enhanced the echogenicity of perfused renal tissue allowing the easy detection of the unenhanced infarct. Because of the increased signal from vessels after PFOB, color Doppler displayed the entire vascular tree, allowing the detection of the truncated embolized branch. The ability of PFOB to enhance Doppler signals and the echogenicity of perfused tissues improved the diagnostic accuracy of sonography when used to detect partial renal infarctions.

Animals↗
PubMed1991

Use of perfluorooctylbromide (PFOB) to detect liver abscesses with computed tomography. Safety and efficacy.

Although perfluorooctylbromide (PFOB) is known to stimulate macrophages, particulates given intravenously (IV) can inhibit the body's response to infection by blocking the reticuloendothelial system. Since PFOB enhances abscesses on computed tomography (CT), the authors evaluated its safety and efficacy by assessing the mortality and abscess volume in 104 rabbits with intrahepatic abscesses given either PFOB or lactated Ringer's (LR), and by comparing its efficacy to that of 76% meglumine sodium diatrizoate (MSD76). Abscesses were produced by injecting a virulent strain of E. coli into the liver. Two days later, five of the rabbits had died. Of the remaining rabbits, 50 were given 5 g/kg PFOB IV, and 49 were given an equal volume of LR. All rabbits had a CT scan at four and at ten days after infusion. They were killed before the second CT scan. Thirty seconds before being killed, 28 rabbits given LR were given a bolus of 2 ml/kg MSD76 IV. Following CT, rabbits were frozen, sliced, and photographed. Abscess volumes were calculated by digitizing the photographs of the anatomic sections and the CT images. MSD76 enhanced the liver by 105 Hounsfield units (HU) more than the liquefied abscess center. The abscess wall enhanced to the same degree as liver, resulting in nonvisualization of three of six abscesses less than 3 mm in size, and a 30% underestimation of true abscess volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Ultrasound contrast agents. State of the art.

In the development of sonographic contrast agents it is clear that the material properties of the contrast have a profound effect on the resulting effectiveness of the product requiring careful manipulations of its properties. The important parameters are particle size, imaging frequency, density, compressibility, particle behavior (surface tension, internal pressure, bubble-like qualities), and equally important biodistribution characteristics and tolerance. Particulate agents appear to be the most likely materials, and gas filled particles are by far the most effective reflectors. However, the gas-based agents reported to date appear to have a short blood half-life. The fluorocarbon emulsions and the solid particles with entrapped air appear to be the most promising agents for abdominal imaging.

Biophysical Phenomena↗
PubMed1991

Magnetic resonance imaging of the scrotum.

MRI demonstrates exquisite anatomical detail of the entire scrotum and inguinal region, adding a new dimension to the assessment of scrotal disease. MRI allows the recognition and distinction of intrascrotal structures and clearly displays their alteration in disease states. MR interpretation is based on a constellation of intrascrotal findings. A specific diagnosis frequently can be made from the MR results combined with the clinical presentation. On the other hand, MR is more expensive and time consuming than sonography and access in many geographic areas is still limited. MRI may be helpful when ultrasound is inconclusive or fails to demonstrate a clinically suspected lesion. In the author's experience, when MR has been the first imaging modality used, ultrasound has not been needed to reach a diagnosis.

Adolescent↗
PubMed1990

Magnetic resonance imaging as an adjunct to sonography in the evaluation of the female pelvis.

Magnetic resonance imaging (MRI) of the pelvis is generally considered to be most beneficial in those cases where the pelvic sonogram is limited or equivocal. All cases that underwent both sonographic and MRI examinations at our institution for the evaluation of the female pelvis in the past two years were retrospectively reviewed. We reviewed the sonographic and MRI reports and the subsequent clinical management in the 41 cases that had both studies to assess whether MRI contributed to the clinical management decision. Both studies were interpreted independently based upon the known clinical and laboratory data available at the time. MRI was obtained in 21 cases because the sonogram was suboptimal or inconclusive. In the other 20 cases it was obtained for additional information, even though the sonogram was diagnostic. Of the 21 inconclusive sonographic studies, MRI established or clarified the diagnosis in all cases. Of the 20 studies where MRI was obtained for additional information, MRI added useful data that helped contribute to the clinical management of 11 patients. MRI is an important adjunct to pelvic sonography. It established, clarified, or added significant data in 78% of cases.

Adult↗
PubMed1990

In vivo estimation of perfluorooctylbromide concentration in tissues.

Currently, the only available method to measure perfluorooctylbromide (PFOB) in tissues requires its extraction with a solvent followed by gas chromatography. Not only is this method invasive, but it cannot be validated because the amount of unextracted PFOB is unknown. Using a cylindrical CT phantom with eight wells in the wall filled with bromine (Br) standards, an in vivo method to measure PFOB tissue concentration was developed. Neutron activation analysis (NAA) was used to calibrate and validate the phantom since NAA allows the quantification of Br by making Br radioactive without the need for extraction. Once NAA was validated for PFOB, the phantom was calibrated using 80 rats and tested using 20 rats relative NAA. The phantom produced linear correlation between CT number and known PFOB concentrations with r = 0.998. After its calibration with NAA, the CT method produced a linear correlation between tissue PFOB concentration determined by CT and NAA near the line of identity with an r = 0.984, thus allowing the determination of PFOB tissue content in vivo noninvasively.

Animals↗
PubMed1990

AUR Memorial Award 1990. The physiologic basis of the radiodense renal medulla after the administration of blood pool contrast agent PFOB.

The hypothesis that the greater CT enhancement of the renal medulla relative to cortex after the administration of perfluorooctylbromide (PFOB) was due to the renal medullary osmotic gradient was tested in eight dogs infused with 10 g/kg PFOB. Urine osmolarity and CT attenuation of the cortex and medulla of each kidney under the full effect of antidiuretic hormone were measured before and after 40 mg of furosemide given intravenously, which is known to destroy the renal osmotic gradient. In an attempt to measure the fractional blood volume of the cortex and medulla, which could account for the observed difference on CT, 10 mCi of 99mTc-labeled erythrocytes were given and cortical and papillary tip tissue samples harvested within 1 minute of the animals' death. Cortical blood volume was eight times that of the medulla (21.6 +/- 5.1% vs 2.7 +/- 0.5%, P less than 0.01) and was not significantly affected by furosemide. Furosemide markedly decreased urine osmolarity (1473 +/- 176 mOsm to 454 +/- 45 mOsm, P less than 0.01), had a minor effect on cortical attenuation (decreased from 90.4 +/- 8.2 to 85.1 +/- 8.1 HU, P less than 0.01), and a marked effect on medullary attenuation (decreased from 140.9 +/- 12.4 to 85.9 +/- 8.9 HU, P less than 0.01) which resulted in total loss of corticomedullary contrast (decreased from 20.0 +/- 3.1% to 0.1 +/- 2.2%, P less than 0.01). Thus, the observed greater CT attenuation of the medulla than cortex following the administration of PFOB, a blood pool agent, is due to the osmotic gradient across the medulla which increases the concentration of the agent in the vasa rectae.

Animals↗
PubMed1990

Subacute scrotal pain: evaluation of torsion versus epididymitis with MR imaging.

Torsion knot and whirlpool patterns result from the twisting of the spermatic cord, which produces distortion of cord structures. These two findings, along with spermatic cord vascularity, were used to prospectively differentiate testicular torsion from epididymitis in 11 patients with subacute scrotal pain who underwent magnetic resonance (MR) imaging. The final diagnosis was established clinically in four patients and surgically in five. MR imaging enabled the recognition of each entity without error. Retrospective review of findings highlighted other potential discriminating features, the most important of which were testicular size and vascularity. Because of its ability to highlight vessels and detail normal and abnormal intrascrotal anatomy, MR imaging in this small series enabled the differentiation of subacute torsion from epididymitis with 100% accuracy. This high degree of accuracy warrants further investigation.

Adolescent↗
PubMed1990

Differentiation of seminomatous from nonseminomatous testicular tumors with MR imaging.

Distinguishing seminomatous from nonseminomatous testicular neoplasms preoperatively is useful because treatment of these two tumors types is different. We evaluated whether the distinction could be made with MR imaging in six patients with seminomatous and nine patients with nonseminomatous testicular tumors (including teratoma, teratocarcinoma, embryonal cell, and choriocarcinoma). The MR diagnoses, which were obtained from the formal reports of the MR studies done and interpreted before orchiectomy, were compared with the pathologic diagnosis. The distinction between the two tumor types on MR images was based on the signal intensity and heterogeneity of the lesion. We also retrospectively compared the MR findings with tissue histology. MR scans in nonseminomatous tumors showed a marked heterogeneous mix of signals, with some regions less intense and others more intense than normal testicular tissue on both proton-density and T2-weighted images. The typical background signal was nearly equal to normal testicular tissue. The tumors also had a dark band at their periphery that correlated with a fibrous tumor capsule on histologic examination. In contradistinction, seminomatous tumors were isointense with testis on proton-density images and consistently hypointense and relatively homogeneous on T2-weighted images. These tumors typically lacked a capsule on MR images. One lesion, only 3 mm in diameter, could not be characterized on MR images because of limitations in spatial and contrast resolution. In 13 of the 14 lesions that could be characterized, the histologic type was predicted correctly on the basis of the MR appearance. The one error occurred in a patient with pure seminoma. Although the MR appearance of the lesion was otherwise similar to the other seminomas, the lesion had a single focus of bright signal that was due to hemorrhage. This focus was interpreted incorrectly as a nonseminomatous element. Our findings in this small series of patients suggest that MR imaging can be used to distinguish seminomatous from nonseminomatous testicular tumors.

Adult↗
PubMed1989

Hemodynamic effects of intravenous lecithin-based perfluorocarbon emulsions in dogs.

We evaluated and compared the acute hemodynamic effects of perfluorooctylbromide-100% (PFOB), a fluorocarbon emulsified in lecithin without pluronic-F68 (F68), to those of a standard iodinated contrast agent, renografin-76% (R76), and Fluosol-DA 20% (Fluosol), a fluorocarbon emulsified in part by F68. Five open chest dogs were instrumented to evaluate hemodynamic changes after iv injection of PFOB (1 ml.1 g/kg) and R76 (1 ml.0.37 g of iodine/kg). Fluosol (1 ml.0.2 g/kg) was given to two of the five dogs at the end of their study. Fluosol caused transient hemodynamic collapse in both dogs. R76 caused the known transient effect of hypotension (-15.4 +/- 3.3%) followed by hypertension (6.5 +/- 2.7%) and an increase in aortic flow (29.3 +/- 3.9% at 30 sec). PFOB caused minimal, clinically insignificant decrease in aortic flow (4 +/- 1% at 10 sec).

Animals↗
PubMed1989

IV injection of air-filled human albumin microspheres to enhance arterial Doppler signal: a preliminary study in rabbits.

When air-filled human albumin microspheres are injected IV, they have been shown to traverse the pulmonary circulation and markedly influence the echogenicity of the left atrium and ventricle. We studied the possibility that the microspheres can be used to enhance the Doppler signal from systemic arteries and the portal vein. Doppler sonography of the aorta, renal artery, intrarenal branch, and portal vein was performed after the IV injection of saline or microspheres in doses of 1.0, 0.5, 0.3, and 0.1 ml in four rabbits. With appropriate blinding of the observers, subjective estimates of enhancement of the Doppler signal were made in each case. All injections of saline had no detectable effect. All four doses of microspheres enhanced the Doppler signal in the aorta in all rabbits. Signals from the renal artery enhanced in all rabbits after injections of 0.3 ml or greater, but in only two rabbits after 0.1 ml. Although the 1.0-ml dose enhanced the Doppler signal from the intrarenal arterial branch in all rabbits, the 0.5- and 0.3-ml doses enhanced signals in two and the 0.1-ml dose in one. The effect was typical for bolus IV injections. The mean time from injection to onset of enhancement was 5 sec and the effect lasted for 12 sec. Portal venous signals were evaluated in three rabbits. Ten injections were made, four at 1.0 ml and two at each of the lesser doses. Portal vein signals enhanced after all four injections of 1.0 ml of microspheres but after only one of the six injections of lower doses. Our results show that the IV injection of air-filled human albumin microspheres enhances the Doppler signal from systemic arteries and the portal vein and that the microspheres have the potential to serve as a contrast agent for Doppler sonography in humans.

Albumins↗
PubMed1989

Diagnostic significance of interslice gap and imaging volume in body MR imaging.

Thin interslice gaps and large imaging volumes are detrimental to MR signal and contrast, especially when the body coil is used. To show the influence of these two factors on fat and water signal and contrast, we performed a series of in vitro experiments. A cylinder filled with water and another filled with oil were imaged transaxially (TR = 2000 msec; TE = 20 and 70 msec) with different interslice gaps (0-150% slice thickness). A series of images was obtained to cover a 40-cm imaging volume. Increasing interslice gap thickness increased water signal without affecting fat signal, resulting in a decrease in fat/water contrast on TE = 20 msec (less T1-weighting) and increasing contrast on TE = 70 msec (more T2-weighting). Contrast nearly doubled when the interslice gap was increased from 10% to 75%. As slices moved away from the central slice, fat and water signals decreased slowly to 12.5 cm off center. Signal loss was significant with offsets greater than 12.5 cm. These results emphasize that to obtain proper contrast on T2-weighted images, the optimal interslice gap should be used and the region of interest should be near the central slice. Otherwise, images should be interpreted with caution.

Body Water↗