Nasser Ghaed

Mammographic and CT detection of extrathoracic lung herniation.

Herniation of lung through the chest wall is uncommon and previously reported cases have been found either clinically or by chest radiography. We recently discovered a case of herniated lung on screening xeromammography. These findings were correlated with thoracic CT.

Radionuclide Demonstration of a Renopleural Fistula Following Trauma

A renopleural fistula was detected on a Tc-99m DTPA renal study during evaluation for possible post-traumatic urinoma.

Gas washout and pressure waveform characteristics of high-frequency oscillation.

High-frequency oscillation (HFO) minimizes tidal volume. To investigate whether ventilation can proceed when tidal movement (volume) is eliminated, a nondis-tensible physical model of interconnected chambers was constructed. During HFO, ventilation was related to pressure waveform characteristics recorded within the separate chambers. Ventilation increased up to a critical frequency related to the time constant of the system. Beyond this frequency, ventilation dropped off rapidly.

Duodenogastroesophageal reflux. Demonstration with Tc-99m DISIDA imaging.

Duodenogastroesophageal reflux is demonstrated using cholescintigraphy in a patient with severe esophagitis.

GLOMERULAR FILTRATION RATE DETERMINED IN CONJUNCTION WITH ROUTINE RENAL SCAN

A method has been developed to estimate glomerular filtration rate (GFR) by means of computer evaluation of information obtained during routine renal scanning with intravenous Tc-99m DTPA. Thirty minutes of data were accumulated as a 30 sec/frame dynamic study following injection, with kidneys and a portion of the heart included in the imaging field. From the computer acquired study, a plasma activity disappearance curve was generated using: (1) a region of interest outlining the imaged portion of the heart, and (2) a single blood sample obtained near the end of the study. Average plasma activity concentration during the study (PAVG) was then determined. Total urinary activity (TUA) generated from onset to conclusion of the study at time T, was determined using subsequent pre- and post-void bladder images, and measured volume and activity of the voided urine. Clearance was calculated using the formula: C1 (ml/min) = TUA DTPA (PAVG)(T) The urinary radionuclide clearance correlated highly with standard 24-hour creatinine clearance over a wide range of clearance values in thirteen patients. The method described to estimate GFR can be performed using less than 40 minutes of imaging time, requires only a single blood sample, does not require measurement of administered dose, is accurate even when the dose is partially or largely infiltrated, and unlike many popular indirect methods for estimating GFR adequately accounts for variations in volume of distribution.

Intraparenchymal Perirenal Pseudocyst Following Trauma

Perirenal pseudocyst (urinoma) is an extravasated collection of urine usually resulting from trauma. The unusual occurrence of the intrarenal location of a pseudocyst is herein first reported.

Masked Obstruction of the Renal Collecting System

Two cases of apparent unilateral renal obstruction in which lesser contralateral obstructions were not seen are presented. In both cases, relief of the more severe obstruction resulted in an unmasking of the milder contralateral lesion.

Differential diagnosis of prolonged cortical retention of radiotracer in technetium-99m DTPA renal scintigraphy.

The mechanisms of prolonged renal cortical tracer retention in Tc-99m DTPA scintigraphy are discussed and a variety of examples are presented.

Hyperalimented lung diagnosed by perfusion scan.

Injection of radiopharmaceutical through a catheter may be useful in localizing its placement. A case is described in which a central venous line had punctured to superior vena cava, delivering hyperalimentation solution into the right pleural space.