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Biomedical subjects

W Kucharczyk

Publications and source records attributed to W Kucharczyk.

At least 73 records · Page 4Linked to original sources
PubMed1986

Intracranial lesions: flow-related enhancement on MR images using time-of-flight effects.

Many physico-anatomic variables and instrument parameters influence the relative magnetic resonance signal intensity of vascular channels. The interaction of these mechanisms is complex, but their composite effects can be accounted for by two main categories of flow phenomena: time-of-flight effects and spin-phase changes. Of these two mechanisms only the time-of-flight effect known as flow-related enhancement produces augmentation of intravascular signal. Flow-related enhancement can potentially provide positive contrast of diagnostic value in terms of anatomic depiction of vascular detail as well as physiologic characterization of blood flow. The authors have used a single-section, selectively irradiated, spin-echo pulse sequence to maximize flow-related enhancement within a variety of intracranial lesions, as a supplement to their regular imaging. The technique was found to be diagnostically useful in improving the conspicuity of vascular lesions, in determining vessel patency, in distinguishing flow void from calcification, and in obtaining semiquantitative information about flow dynamics.

Brain Diseases↗
PubMed1986

MRI of angiographically occult vascular malformations.

Eleven patients with 15 angiographically occult arteriovenous malformations were studied by magnetic resonance (MR) imaging and computed tomography (CT). Five patients had biopsy proof; six were clinically diagnosed from the long-term clinical follow-up (more than 3 years) and imaging features. Of the 15 lesions, 11 were recognized by both CT and MR. Each method was falsely negative for two lesions. The most useful contribution of MR in the characterization of angiographically occult arteriovenous malformations was the depiction of hemorrhagic foci in 12 of 13 lesions seen on MR. High-attenuation foci indicative of hematomas were seen in only five lesions on CT; the rest were iso- or hypoattenuating. CT detected two very small lesions, in one case as punctate foci of enhancement and in the other as punctate calcification, that were not seen with MR. MR complements CT in characterizing angiographically occult arteriovenous malformations and in distinguishing them from similar-appearing lesions, in particular, small neoplasms. However, when such lesions are seen with only focal calcification and subtle enhancement on CT, routine MR may miss them.

Adolescent↗
PubMed1986

Magnetic resonance characterization of non-flowing intravascular blood.

We eliminated the effects of flow on the magnetic resonance (MR) appearance of intraluminal blood by imaging the superficial veins in the arms and legs of 3 volunteers during venous occlusion with tourniquets. T1, intermediate and T2 weighted transaxial images were obtained using a multisection spin-echo technique at 1.5 T. The images were analyzed by visual inspection and by region of interest pixel intensity measurements. The intensity of non-flowing blood was compared with muscle, fat and a tube of water taped to the skin. We determined that non-flowing, unclotted blood has intermediate T1 characteristics and long T2 characteristics. On T1 weighted images, non-flowing blood is of greater signal intensity than water or muscle, but less than fat. On T2 weighted images, non-flowing blood is of greater signal intensity than fat and muscle, but slightly less than water. These results may help explain the signal observed with very slow intravascular flow and hyperacute intracranial hematomas, where intermediate T1 and long T2 relaxation characteristics are reported.

Blood Flow Velocity↗
PubMed1986

Magnetic resonance imaging of spinal cord hemangioblastoma.

We retrospectively reviewed the magnetic resonance (MR) studies in nine patients with spinal cord hemangioblastoma. Five patients were studied with a low field magnet (0.35 T/0.5 T) and four with a high field magnet (1.5 T). Six tumors were thoracic and three cervical in location. Magnetic resonance imaging (MRI) was positive in all the nine patients. MRI permitted a specific diagnosis prior to angiographic evaluation of the cord in three patients. The most characteristic findings in such tumors were: an intramedullary vascular nodule, enlarged drainage vessels, diffuse enlargement of the cord, and/or intramedullary cyst. The high field magnet showed a greater sensitivity in detecting vascularity within the nodule and draining vessels than did the low field magnet. MRI should be the first procedure in patients with myelopathy and subarachnoid bleed of spinal origin and for screening patients with von Hippel-Lindau disease.

Adult↗
PubMed1985

Central nervous system tumors in children: detection by magnetic resonance imaging.

Fifty-one pediatric patients who were suspected of having central nervous system (CNS) tumors underwent magnetic resonance (MR) imaging using a 0.35 T Diasonics MT/S system. Pulse intervals (TR) ranged from 0.5 to 2.0 seconds with echo delays (TE) of 28 and 56 msec. The ability of MR and contrast-enhanced CT to detect focal lesions, determine lesion extent, and evaluate associated abnormalities was compared. In most patients in whom there was suspected spinal cord disease, comparison with myelography was made. Thirty-three intracranial lesions were detected with at least one imaging modality in 43 cranial examinations. MR was judged superior to CT in 14 of these cases and CT superior to MR in only one. Of eight spinal examinations, there were six that demonstrated abnormal findings. MR was superior to CT in all six cases and better than myelography in four of five cases where myelography was performed. Spin echo (SE) sequences with long pulse intervals were the most sensitive, but in some cases short pulse intervals permitted further characterization of the lesion. Patient motion was not a problem; sedation was routinely used in children younger than five years of age. MR imaging has rapidly become a valuable diagnostic modality in neuroradiology. The lack of ionizing radiation and the ability to evaluate the spinal cord noninvasively makes it particularly attractive in examination of children.

Adolescent↗
PubMed1985

Cystic intracranial lesions: magnetic resonance imaging.

Thirty-three patients with cystic intracranial lesions were examined with both magnetic resonance (MR) imaging and CT scanning. The abnormalities imaged included 11 arachnoid cysts, 10 cystic tumors, six postoperative cysts, and three colloid cysts. The intensity patterns of the cyst contents as encoded with routine spin-echo imaging sequences enabled subdivision of the cysts into three categories. Arachnoid and postoperative cysts had an intensity pattern identical to cerebrospinal fluid. More proteinaceous cysts, including inflammatory cysts and nonhemorrhagic tumoral cysts, had an intermediate intensity pattern with characteristically low intensity on the short TR sequence (0.5 sec), but had clearly higher intensity than cerebrospinal fluid on the long TR sequences (2 sec). Finally, three cystic tumors with hemorrhagic fluid and three colloid cysts had a distinctly different pattern of high intensity on all four MR sequences through the same section. MR was superior to CT in characterizing intracranial cystic lesions because of its ability to categorize cysts into these three groups on the basis of the intensity pattern of cyst contents, thereby improving diagnostic specificity and patient management.

Adolescent↗
PubMed1985

Intracranial vascular malformations: MR and CT imaging.

Twenty-four patients with 29 cerebrovascular malformations were evaluated with a combination of computed tomography (CT), angiography, and magnetic resonance (MR) imaging. Characteristics of the malformations on MR images were reviewed retrospectively, and a comparative evaluation of MR and CT images was made. Of 14 angiographically evident malformations, 13 intra-axial lesions were detected on both CT and MR images, and one dural malformation gave false-negative results on both modalities. The appearance of parenchymal lesions on MR images closely mirrored characteristic CT findings. Calcific foci were difficult to separate from vessels on both images. Clot was more easily identified on MR images. In the detection of 15 angiographically occult malformations, CT proved more sensitive when focal calcification was the only evidence of their presence. MR study failed to detect two small supratentorial lesions evidenced by faint calcifications on CT scans. In two patients, MR images showed small hemorrhages not detectable by CT, and MR provided strong evidence for the diagnosis of hematoma for 12 lesions. Angiographically evident malformations have a highly characteristic appearance on MR images. MR may be more sensitive than CT in the detection of small hemorrhagic foci associated with cryptic arteriovenous malformations and may add specificity in the diagnosis of occult malformations in some cases, but MR is less sensitive than CT for the detection of small calcified malformations.

Adolescent↗
PubMed1985

MR technology: effect of even-echo rephasing on calculated T2 values and T2 images.

In multiple spin-echo image sequences of blood flow, the "even-echo" phenomenon produces an absolute increase in signal magnitude from first- to second-echo images of normal vessels harboring slow flow. Distinguishing this from the apparent relatively high signal intensity seen on second-echo images in pathologic foci of stationary tissue is important to the diagnostician. Selected case material containing two tissue types was reviewed retrospectively: tissues known to harbor slow flow, such as normal veins and venous sinuses and vascular malformations, and tissues that have long transverse (T2) relaxation times and appear as intense structures on second-echo images, such as neoplasms, infarcts, and regions of demyelination. Calculations of T2 parameters were made by computer for defined regions of interest. T2 images were also generated. Visual inspection of the acquired images did not reliably distinguish increased intensity due to even-echo rephasing from the relative changes between adjacent tissues seen on second-echo images. More definitive differentiation of the even-echo phenomenon was provided by calculated values of T2 and computer-synthesized T2 images representing acquired intensity data of two-echo sequences. The synthesized images were especially useful when stationary tissue with lengthened T2 values was adjacent to or in proximity to vessels or vascular lesions. A five spin-echo image sequence was valuable for separating slow flow from stationary tissue by a technique of synthesizing T2-difference images using three consecutive echoes.

Brain Diseases↗
PubMed1985

MR imaging of calcified intracranial lesions.

Fifty calcified intracranial lesions diagnosed with computed tomography (CT) were evaluated with magnetic resonance (MR) using a spin-echo sequence. MR images demonstrated 41 of 50 lesions seen as calcified on CT scans, among them 29 of 30 cerebral neoplasms and all ten arteriovenous malformations. The presence of calcification was suspected prospectively in about 60% of calcified lesions but was also suspected in 45% of uncalcified lesions (reviewed as control cases). No fine calcifications and only 25% of punctate calcifications were disclosed on MR images. In the nine lesions undetected by MR, calcification was the only abnormal CT finding. The findings of calcification on MR images were nonspecific, ranging from signal void or signal dampening on all sequences to no alteration of signal intensity. The most common finding of calcification was a focus of signal diminution, rather than signal void, as commonly reported.

Adolescent↗
PubMed1985

Magnetic resonance imaging of the central nervous system--an update.

Magnetic resonance imaging has developed rapidly and now has superior ability to detect and to characterize disease in the central nervous system without any significant biologic hazard. It is becoming the screening method of choice in the diagnosis of neoplasm, ischemia, hemorrhage, infection and degenerative and demyelinating diseases involving the central nervous system.

Central Nervous System Diseases↗
PubMed1982

Cardiac tamponade as a complication of thin-needle aspiration lung biopsy.

Thin-needle aspiration lung biopsy has become an important diagnostic technique in chest disease. Complications, other than pneumothorax, are infrequent. We report a case of acute cardiac tamponade complicating biopsy of a lesion near the mediastinum. Caution should be exercised in selecting patients for, and in performing biopsies in, or close to the mediastinum.

Adult↗