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Biomedical subjects

H Kangarloo

Publications and source records attributed to H Kangarloo.

At least 19 recordsLinked to original sources
PubMed1992

The pediatric patient with suspected adrenal neoplasm: which radiological test to use?

To establish which radiological test to use in a pediatric patient with suspected neoplasm, we retrospectively studied 19 children with proven adrenal neoplasm who had a combination of ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). The results show that US should remain the initial imaging modality for evaluating abdominal masses in children but that MRI is more accurate than CT and US in detecting the organ of origin and the extent of an adrenal lesion and should, therefore, be the modality of choice for the definitive evaluation of adrenal neoplasm in children.

Adolescent↗
PubMed1992

Design of a high-speed, high-resolution teleradiology network.

A teleradiology system acquires radiographic images from one location and transmits them to one or more distant sites where they are displayed and/or converted to hard-copy film recordings. The long-term goal of teleradiology research is to show that teleradiology systems can provide diagnostically equivalent results when compared with conventional radiographic film interpretation. If this hypothesis is proven, provision of the following radiology services will be improved: (1) providing for primary interpretation of radiological images for patients in underserved areas as well as in other medical facilities; (2) integration of radiological services for multihospital/clinic health care provider consortiums; (3) improving emergency service and intensive care unit coverage; (4) offering consulting-at-a-distance with subspecialty radiologists; and (5) providing radiologists in the community or in rural areas with immediate access to large academic centers for help in the interpretation of difficult and problematic cases. We are designing a high-speed, high-resolution teleradiology network that will communicate between our level 3 medical center and several outlying medical centers within the metropolitan area. Computed tomography (CT), magnetic resonance (MR), and screen-film examinations will be digitized to 2,000 x 2,000 or 4,000 x 4,000 pixels at the remote sites, transmitted to the central referral facility, and sent to a laser film printer, replicating the original film. This film may then be used for primary diagnosis, overreading/consultative purposes, or for emergency department preparation. Inherently digital modality data (eg, MR and CT) can be sent without digitization of the multiformat film if desired.

Computer Communication Networks↗
PubMed1992

Magnetic resonance image synthesis from analytic solutions of spin-echo and radio frequency-spoiled gradient-echo images.

RATIONALE AND OBJECTIVES: To synthesize magnetic resonance images (MRI) in real-time using a minimal data set obtained with routine clinical protocols and stored in a picture archiving and communication system (PACS) database. METHODS: Analytic solutions for T1 and T2 were obtained from a double and a single spin-echo set, with routine parameters. Analytic solutions from radio frequency-spoiled gradient-echo images, with TRs as low as 33 mseconds, also were used to synthesize gradient-echo images. RESULTS: Phantom studies showed that the errors in the synthesized images were significantly smaller than the errors in the T1- and T2-calculated images and similar to the source images. The gradient-echo images resulted in significant scan time savings. CONCLUSION: MRI synthesis from analytic solutions of T1, T2, and rho saves computational time and yields accurate values for the intrinsic parameters while allowing the use of routine clinical protocols. The availability of clinical images in the PACS database and the ability to synthesize images in real-time has allowed the development of a practical interactive teaching module.

Brain↗
PubMed1992

Metastatic head and neck malignancy treated using MRI guided interstitial laser phototherapy: an initial case report.

Interstitial laser phototherapy (ILP) guided by magnetic resonance imaging (MRI) may become an attractive adjunctive modality for the treatment of deep and surgically inaccessible tumors of the head and neck when accurate methods of laser dosimetry and "real-time" monitoring techniques with the MRI are introduced. We recently demonstrated in ex vivo and in vivo models, a linear relationship between levels of laser energies, thermal profiles, MR signal intensity changes, and histopathological tissue damage. Results of treatment in a patient with an unresectable large right jugulodigastric metastatic squamous carcinoma using new approach of MRI guided ILP are now reported. The patient complained of significant right-sided neck pain and headaches secondary to a rapidly growing metastatic lymphadenopathy which recurred after previous surgery, radiation, and chemotherapy. Two treatment sessions were used at an interval of 2 weeks. Each treatment was performed in the MRI suite under heavy sedation. Using a 600-microns bare fiber of the Nd:YAG laser implanted interstitially under MR guidance, the metastatic node was treated at three sites. T1- and T2-weighted images were performed prior to, immediately after, 24 and 48 hours, and 4, 5, 7, 9, 16, and 25 days post-treatment. Successful relief of pain and growth arrest of this node was observed after the second treatment and at the 3-month follow-up. These results demonstrate that this technique of ILP guided by MRI may be feasible in humans, and will become clinically practical when appropriate methods of dosimetry and instrumentation are developed.

Aluminum Silicates↗
PubMed1992

Congenital disorders of sexual differentiation: MR findings.

A broad spectrum of anomalies of sexual differentiation may exist at birth. These include male and female pseudohermaphroditism, gonadal dysgenesis, and true hermaphroditism. When ambiguous genitalia are present, expedient identification of the anomaly is required for proper gender assignment and appropriate surgical or hormonal correction. As the appearance of the external genitalia often is not distinctive enough to make a specific diagnosis, this must be accomplished by clinical findings along with a combination of cytogenetic, biochemical, and radiologic studies. Because the causes of abnormal sexual differentiation are diverse and often exhibit incomplete expression, they produce much anatomic variability. Sonographic and radiographic studies are often used initially to evaluate such conditions. The noninvasive multiplanar nature of MR imaging makes it a useful alternative method with which to characterize the abnormal anatomy in this group of disorders, as we illustrate in this pictorial essay.

Disorders of Sex Development↗
PubMed1992

Receiver-operating-characteristic study of chest radiographs in children: digital hard-copy film vs 2K x 2K soft-copy images.

Two methods are commonly used to visualize digital radiologic imaging data: (1) hard-copy viewing, in which the digital data are used to modulate the intensity of a laser beam that exposes an analog film and (2) soft-copy viewing, in which the digital data are converted to an analog video signal and presented on a CRT monitor. The film method allows new digital imaging systems to be easily integrated into conventional radiologic management and viewing methods. The second method, soft-copy viewing, allows digital imaging data to be managed and viewed electronically in a picture archiving and communication system (PACS). These PACS systems are hypothesized to have improved operational efficiency and enhanced image-analysis capabilities. The quality of soft-copy images is still not widely accepted. This article reports on the results of a large-scale receiver-operating-characteristic study comparing observers' performance in detecting various pediatric chest abnormalities on soft-copy 2048 x 2048K byte displays with their performance with digital laser-printed film from computed radiography. The disease categories studied were pneumothorax, linear atelectasis, air bronchogram, and interstitial disease. The selected data set included 239 images; 77 contained no proved abnormality and 162 contained one or more of the abnormalities mentioned. Seven pediatric radiologists participated in the study, two as judges and five as observers. Our results show no significant difference between viewing images on digital hard copy and soft copy for the detection of pneumothoraces and air bronchograms. A slight performance edge for soft copy was seen for interstitial disease and linear atelectasis. This result indicates that computed chest radiographs in children viewed in a soft-copy PACS environment should result in diagnoses similar to or slightly more accurate than those obtained in a laser-printed film-based environment.

Child↗
PubMed1992

A PACS-based interactive teaching module for radiologic sciences.

This article describes an interactive teaching module, linked to a picture archiving and communications system (PACS) data base, for teaching radiology. The module is currently tailored to MR images but can be adapted to any other imaging technique. An algorithm has been developed that allows the use of MR images acquired with routine clinical protocols and stored in the data base to yield, in real time, images at any other arbitrary TE and TR. In the browse mode, the user can study either the effect of different scan parameters or clinical cases on synthesized or acquired images. The quiz mode has multiple-choice questions and answers, accompanied by images. In the teaching mode, the instructor has access to the clinical data base and WRITE privileges for setting up the browse or quiz mode. The module achieves considerable flexibility when linked to the PACS, with access to all archived images and the ability to subsequently synthesize MR images at arbitrary TE and TR values in real time. The module is also "dynamic" in character, in that the instructor can easily add new cases and comments to the teaching files, both to enhance its clinical aspects and to reflect advances in technology.

Algorithms↗
PubMed1991

Renal ultrasound abnormalities in children with end-stage liver disease--reversal by liver transplantation.

Ultrasound (US) imaging of the kidneys was performed in 43 pediatric patients with end-stage liver disease evaluated for orthotopic liver transplantation. Renal size was increased in 8 patients (19%) and echogenicity of the kidneys was increased in 12 patients (28%). In 12 patients studied after liver transplantation, US revealed normal renal size in all and increased echogenicity in only 2 patients shortly after transplantation. Normalization of renal US findings was also found in 2 patients studied before and after liver transplantation. The glomerular filtration rate varied from 65 to 225 ml/min per 1.73 m2 in 5 patients with abnormal US, and from 74 to 116 ml/min per 1.73 m2 in 3 patients with normal US. Nephromegaly and increased echogenicity on renal US are frequent in children with end-stage liver disease and appear to be mostly reversible by liver transplantation.

Adolescent↗
PubMed1991

Future directions of laser phototherapy for diagnosis and treatment of malignancies: fantasy, fallacy, or reality?

A new and highly promising adjunctive modality for the diagnosis and therapy of malignancies is under development using lasers and tumor targeting dyes. To reach the eventual goal of clinical treatment, several current "fantasies and fallacies" regarding laser applications in medicine must be identified and their problems clearly outlined. A multidisciplinary scientific approach is also required to enable the clinical practicality of this laser targeting approach. Many new dyes and laser wavelengths are being tested to improve specific tumor uptake and/or retention, lower systemic toxicity, increase tissue penetration, and identify fluorochromes with synergistic properties to further enhance laser tumoricidal effects. Rapid technological advancements in magnetic resonance imaging may now provide an extremely sensitive way to detect and monitor laser-tissue effects, and allow efficient interstitial laser phototherapy of deep and sometimes inaccessible tumors. The current and future prospectives of the emerging field of laser phototherapy are described.

Coloring Agents↗
PubMed1990

Advances in medical imaging.

The field of medical imaging, stimulated by advances in digital and communication technologies, has grown tremendously. New imaging techniques that reveal greater anatomical detail are available in most diagnostic radiology departments. We discuss vascular imaging with ultrasound, high-resolution computed tomography of the thorax, magnetic resonance imaging applications, and picture archiving and communication systems. Vascular imaging with ultrasound requires duplex and color flow Doppler, which combine gray-scale ultrasound and the Doppler phenomenon. High-resolution computed tomography modifies conventional computed tomography technology and results in images with higher spatial resolution. Magnetic resonance imaging applications for all areas of the body are being investigated and are replacing older roentgenographic techniques such as computed tomography, arthrography, myelography, and even angiography in a growing number of indications. With these new digital imaging modalities, image management has become an important consideration that can be addressed by picture archiving and communication systems.

Diagnostic Imaging↗
PubMed1989

Magnetic resonance imaging of the musculoskeletal system in children.

Pediatric applications of magnetic resonance imaging (MRI) differ from those in adults primarily with respect to the focus on congenital and developmental abnormalities and those pathologic conditions that are unique to children. Sedation is often required for younger children to avoid motion. Quality diagnostic images also require the use of appropriate sizes of surface and planar coils. MRI is an excellent method to evaluate bone marrow involvement and soft-tissue extension of osteosarcoma and Ewing's sarcoma. In children, it is important to be aware of the changes in normal bone marrow signal that occur with maturation and with the normal progression of the replacement of red marrow by yellow marrow. Aplastic and hypercellular anemias have differing MRI features. The high-contrast resolution of the soft tissues, including the spinal cord, and the capability for direct imaging in any plane make MRI an excellent modality for the evaluation of the spine, including congenital malformations.

Bone Marrow↗
PubMed1988

Acquired cystic kidney disease in children undergoing long-term dialysis.

Acquired cystic kidney disease (ACKD) occurs in adult patients undergoing long-term dialysis. Early detection is important because clinically significant hematuria and malignancies are associated with ACKD. We evaluated by magnetic resonance imaging (MRI) and ultrasonography (US) the incidence of ACKD in 15 patients aged 7.3-21.6 years (mean 15.9 years) with non-cystic primary renal disease. Nine patients had been treated with peritoneal dialysis only, and 6 with both hemodialysis and peritoneal dialysis for 24-73 months (mean 37 months). Three patients (20%) had no cysts. In 5 patients (33%) with bilateral multiple cysts, the diagnosis of ACKD was made by MRI and US. In another 5 patients, solitary cysts were localized to one kidney by MRI, and in 2 patients solitary cysts were seen in both kidneys. This study documents that ACKD is not limited to older patients with end-stage renal disease. Early detection of these cysts can be accomplished by MRI and is warranted since 1 patient developed neoplastic tubular changes which can precede tumor formation.

Adolescent↗
PubMed1988

Primary liver tumors in children: comparison of CT and MR imaging.

A prospective study was performed at two institutions to determine the role of magnetic resonance (MR) imaging in the evaluation of primary pediatric liver tumors. The study compared the usefulness of MR imaging and computed tomography (CT) in providing a correct diagnosis, assessing resectability, and determining tumor recurrence in 23 children with liver tumors. The information obtained with both modalities was correlated with surgical data. The results indicate that the accuracy of MR imaging in helping to differentiate benign from malignant lesions is high and identical to that of CT, but not good enough to obviate surgical diagnosis. While all five hepatocellular carcinomas were correctly diagnosed preoperatively with both modalities, neither CT nor MR imaging could help differentiate these carcinomas from aggressive hepatoblastoma or primary hepatic lymphoma. MR imaging helped correctly predict tumor resectability in all 18 children with malignant hepatic tumors; in one, exact tumor extension was misjudged with CT. Postoperative MR studies suggested tumor recurrence in three children who had unremarkable CT examinations. Second-look surgery showed recurrent tumor in two and fibrosis with chronic inflammation at the surgical margin in the third child.

Adolescent↗
PubMed1988

Magnetic resonance imaging of iron overload in children treated with peritoneal dialysis.

The ability of magnetic resonance imaging (MRI) to detect iron overload in children with end-stage renal disease (ESRD) was studied in 18 multiply transfused patients, aged 15.5 +/- 4.8 years, and 5 nontransfused children without evidence of renal disease. In the transfused patients, the serum ferritin (SF) level was compared to (a) a subjective rating of signal intensity of MRI images (scale of 0-10), (b) mean T1 values of liver and spleen, and (c) computer-assisted measurements of spin echo intensity (SEI) of liver, spleen, muscle and fat tissue. On subjective evaluation, the mean signal intensity was significantly lower in transfused patients than in controls and a significant correlation with the SF levels was observed for ratings of both liver and spleen. Mean T1 values of liver and spleen did not correlate with the SF levels. On computer analysis, the ratios of SEI of fat/liver, fat/spleen, muscle/liver and muscle/spleen were significantly correlated with the SF levels as well as the subjective evaluation sources. These data indicate that MRI is a suitable technique of documenting the presence and degree of iron overload in multiply transfused children with ESRD.

Adolescent↗