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Biomedical subjects

P Prassopoulos

Publications and source records attributed to P Prassopoulos.

67 records · Page 4Linked to original sources
PubMed1992

CT evaluation of compensatory renal growth in relation to postnephrectomy time.

In 27 patients nephrectomized for renal carcinoma, the compensatory hypertrophy of the remaining kidney was assessed by 72 CT examinations performed one month before and during 32 months after nephrectomy. Kidney size was estimated on CT by multiple measurements of the renal parenchymal thickness. Kidney growth was evaluated by comparing the amount of renal parenchyma before and after contralateral nephrectomy. Renal compensatory hypertrophy varied with postnephrectomy time. Kidney enlargement was 15% in the first 3 months, reached maximum 30% about a year later, and was reduced to 5%, 2 1/2 years postoperatively.

Adult↗
PubMed1990

The thickness of the renal parenchyma decreases with age: a CT study of 360 patients.

Renal parenchymal thickness was estimated by using CT in 360 patients with no evidence of renal disease. In each patient, the measurements were normalized to the transverse diameter of the vertebral body and a reference table was formulated. The renal parenchymal thickness decreases about 10% per decade of increasing age in both men and women. These findings are consistent with previously reported findings based on autopsy material. The proposed table may be useful as a criterion for assessing normal renal parenchyma on CT.

Adult↗
PubMedDate not supplied

Interposition of the colon between the kidney and the psoas muscle: a normal anatomic variation studied by CT.

The position of the bowel in the pararenal space was examined in relation to the kidney and the psoas muscle in 1203 abdominal computed tomographic (CT) examinations. The ascending colon was found between the lower kidney pole and the psoas muscle in 1.7% and the descending colon in 0.7% of the patients. This variation appeared more frequently in women, young adults, and individuals with less intrabdominal fat. Lateral displacement of the lower kidney pole was observed in 40% of the patients with this normal variation. These findings may be of value when interpreting urographic and abdominal CT examinations.

Adult↗
PubMedDate not supplied

Optimization of a contrast medium suitable for conventional enteroclysis, MR enteroclysis, and virtual MR enteroscopy.

BACKGROUND: The purpose of the current study was to optimize a gadolinium-barium sulfate solution suitable for performing conventional and MR enteroclysis examinations in the same session. METHODS: Eighteen vials of 20% barium sulfate and various gadolinium concentrations (lower 0 ml/lt, higher 45 ml/lt) were prepared and placed in the magnet. The imaging protocol was consisted of the following sequences: true FISP, HASTE with fat saturation and 3d FLASH with fat saturation in various flip angles. Ten patients underwent conventional enteroclysis with 1.2 lt of 20% barium sulfate enema and 18 ml of gadolinium. MR enteroclysis was performed afterwards using true FISP, fat suppressed 3d FLASH and fat suppressed HASTE sequences. RESULTS: The lowest gadolinium concentration in the barium sulfate solution generating low intraluminal signal on HASTE and high intraluminal signal on true FISP and 3d FLASH sequences was 15 ml/lt. The presence of gadolinium did not influence the lumen opacification in conventional enteroclysis examination. In all patients the proposed contrast medium acted as positive in 3d FLASH (T1w), true FISP (T2/T1 w) and as a negative in HASTE (T2w). Bowel wall conspicuity, lumen opacification and distention were ranked as very good to excellent on MR enteroclysis images while artifacts level did not downgraded the overall image quality. High quality virtual MR endoluminal views of the small bowel, based on 3d FLASH images, were obtained in all cases. CONCLUSION: A 20% barium sulfate enema with 15 ml/lt gadolinium is appropriate for conventional and MR enteroclysis examinations.

Adolescent↗
PubMedDate not supplied

Suprapubic versus transrectal ultrasonography in assessing the volume of the prostate and the transition zone in patients with benign prostatic hyperplasia.

The reliability of suprapubic ultrasonography (SU) in assessing the size of the prostate was examined in 95 patients with benign prostatic hyperplasia (BPH). Volumetric measurements of the prostate and the transition zone of the prostate (TZP) performed by SU were compared with corresponding measurements obtained by transrectal ultrasonography measurements obtained by transrectal ultrasonography (TU). A very strong correlation was found between suprapubically and transrectally performed measurements for both the total prostate gland (r = 0.948, p < 0.001) and the TZP volume (r = 0.953, p < 0.001). According to the results of this study, SU appears to be reliable as TU in assessing the size of the prostate and the TZP and may be used effectively in the evaluation of patients with BPH, as it is less cumbersome, better tolerated, and a widely available examination technique.

Aged↗
PubMedDate not supplied

A study of the variation of colonic positioning in the pararenal space as shown by computed tomography.

In a review of 1708 consecutive CT examinations of the abdomen the position of the ascending and descending colon in relation to the posterior and lateral edge of the kidney was studied. It was found that part of the colon was positioned posterior or posterolateral to the kidney's edge in percentages that varied between 14.2% and 0.9% in the different sex groups at the levels of upper, mid- and lower poles of the right and left kidney. It is concluded that this anatomical variation should be known if colon perforation is to be avoided during percutaneous nephrostomy or biopsy.

Adult↗
PubMedDate not supplied

Image analysis methods for solitary pulmonary nodule characterization by computed tomography.

Computer software was designed for classifying solitary pulmonary nodules (SPNs) into benign and malignant from their CT images, using image analysis methods. The system made use of three features, computed from the CT density matrix of the SPN, and a class-discriminating algorithm. System evaluation was performed on 51 histologically confirmed SPNs of indeterminate CT diagnosis. Overall classification accuracy in distinguishing benign and malignant SPNs was 90.2%, while 83.3% of the benign and 93.9% of the malignant SPNs were correctly classified. The proposed system may be of value to the radiologist in assessing the probability of malignancy in patients with a solitary pulmonary nodule.

Adult↗
PubMedDate not supplied

Tailored low dose three-dimensional CT of paranasal sinuses.

A technique for three-dimensional (3D) computed tomography (CT) of the paranasal sinuses was evaluated. The influence of milliamperage and reconstruction algorithms on image quality was studied in a phantom. Eleven patients with bony abnormalities of the paranasal sinuses underwent CT to assess the clinical impact of 3D CT protocol. Contiguous 1.5-mm sections obtained at 120 kVp/175 mA/1.9 sec can provide 3D images with high diagnostic image quality. This technique offers the advantage of a much lower dose than that of the conventional CT (CCT) examination of paranasal sinuses. Three-dimensional CT protocol of paranasal sinuses is suggested for use for the evaluation of bony abnormalities and for preoperative planning of the above region.

Humans↗
PubMedDate not supplied

The bicipital groove as a landmark for orientation of the humeral prosthesis in cases of fracture.

We studied 45 dry cadaveric humeri to determine whether the bicipital groove of the humerus can be used as a landmark for a proper, individualized orientation of a humeral prosthesis, especially in the case of a fracture. We performed 3 computed tomography sections (at a level just below the lower portion of the head, at the middle of the humeral head, and at a distance 5 cm below the first section), and we used special software for 3-dimensional image processing. To reproduce the individual posterior version of the head, when a humeral prosthesis is implanted for fracture, the lateral fin of the prosthesis should be a mean distance 5.2 +/- 2.6 mm (-1.5 to 10.7 mm) from the posterior edge of the bicipital groove. If the lateral fin of the humeral prosthesis seats just behind the posterior edge of the bicipital groove, a difference of -6.3 degrees to 41.7 degrees from the normal posterior version occurs. A new, simple methodology for an individualized posterior version of a humeral prosthesis in cases of fracture is proposed. We applied this in 6 consecutive patients with fracture of the humeral head that required hemiarthroplasty.

Cadaver↗
PubMedDate not supplied

Retropsoas positioned bowel: incidence and clinical relevance.

PURPOSE: Our goal was to assess the incidence of retropsoas positioned large or small bowel in the population and to examine factors predisposing to its formation. METHOD: The presence of retropsoas positioned bowel was retrospectively studied in 1,852 abdominal CT examinations of 1,055 men and 797 women, 648 younger and 1,204 older than 50 years. All examinations were considered normal or demonstrated findings that were unrelated to the position of the bowel. RESULTS: Retropsoas positioned colon (RPC) was observed in 51 (2.8%) cases for the ascending and 45 (2.3%) for the descending colon. RPC appeared more frequently in younger (< 50 years) than older patients and in individuals with decreased amount of retroperitoneal fat. Retropsoas position of small bowel loops was observed in 11 (0.6%) patients, all exhibiting paucity of retroperitoneal fat. CONCLUSION: Because of its prevalence, retropsoas positioned bowel should be considered when performing percutaneous diskectomy or other interventional procedures in the posterior retroperitoneum.

Adult↗
PubMedDate not supplied

Computer image analysis of brain CT images for discriminating hypodense cerebral lesions in children.

A computer software system was designed for the automatic discrimination of focal oedemas from local glioses in brain CT examinations. Image analysis methods were applied to the images of 77 CT examinations of children with focal oedemas (42) or local glioses (35). Textural features derived from the co-occurrence matrix of the lesion's image and a neural network classifier (the multilayer perceptron) were employed for the design of the system. Best classification accuracy (89.6%) was achieved by two textural features (contrast-difference entropy), one hidden layer and three hidden nodes of the classifier. The proposed software system provides new textural information and may be of value to the radiologist in differentiating focal oedemas from local glioses, especially in small lesions, where other radiological criteria are not evident.

Brain↗
PubMedDate not supplied

Maturation of the tract after percutaneous cholecystostomy with regard to the access route.

PURPOSE: To assess the shortest time for catheter removal with regard to the transhepatic or transperitoneal approach in patients undergoing percutaneous cholecystostomy (PC). METHODS: In this prospective study, 40 consecutive high-risk patients with acute cholecystitis (calculous, n = 22; acalculous, n = 18) underwent PC by means of a transhepatic (n = 20) or transperitoneal (n = 20) access route. In 28 patients (70%) computed tomography was used for puncture guidance, while in the remaining 12 (30%) the procedures were formed under ultrasound control. A fistulography was performed on the 14th postprocedural day in al patients and was repeated weekly if the tract was found to be immature. The catheter was removed only if a mature tract without evidence of leakage was delineated. RESULTS: In 36 of 40 patients the procedure was technically successful (90%). Three of the unsuccessful punctures were attempted transperitoneally and one transhepatically. Thirty-five of 36 patients showed rapid improvement within the first 48 hr following the procedure (96%). Three of them died of their severe underlying disease (7.5%) and in another three the catheter was accidentally removed prior to the first fistulography (7.5%) A total of 30 patients could be fully evaluated after the procedure: 15 with a transhepatic, and 15 with a transperitoneal PC. Whereas 14 of 15 patients (93%) with transhepatic gallbladder access developed a mature tract after 14 days and the remaining patient after 3 weeks, only 2 of 15 patients (13%) with a transperitoneal route presented a mature tract after 2 weeks (p < 0.0001; chi2 test with Yates' correction). Eleven patients (73%) with transperitoneal access required 3 weeks and two patients (13%) 4 weeks for complete tract formation. CONCLUSION: A period of 2 weeks suffices for the majority of patients to develop a mature tract when the transhepatic access route is used; when using the transperitoneal route at least 3 weeks are required. We suggest that the transhepatic route is preferable since it allows earlier removal of the catheter and reduces the incidence of complications and discomfort for the patients.

Acute Disease↗