Dual-time [99m] TC-MAG3 diuretic renography and new criteria in the assessment of obstructive uropathy

Obstructive pattern within hydronephrotic non-obstructed kidney is frequently encountered during [99m] TCMAG3 diuretic renography. The aim of this study was to assess the value of applying new protocol and criteria on dual-time imaging in ruling out obstruction. We included 53 children [56 kidneys] in this study [28 boys and 25 girls with age range three weeks to 12 years]. All had hydronephrosis, which was bilateral in three children. Eighteen children had pyeloplasty, while 35 children had no previous surgical interventions. All children were referred for assessment of renal outflow obstruction and kidney function. All children underwent routine diuretic [99m]Tc MAG3 renal renography. All had obstructive patterns during diuretic [99m] TcMAG3 renography and underwent a second dynamic study 30 minutes later for 10 minutes. Non obstructive criteria were set as down sloping second time renogram with drop of kidney counts by 50% of peaked activity in first time renogram. Obstructive criteria on dual-time imaging were set as progressive rising second time renogram or flat second time renogram with drop of kidney counts by less than 30% compared to first time study. Equivocal criteria were set as flat renograms with drop of kidney activity by 3 0-50% or down sloping renogram with drop of kidney counts by<30% over 10 minutes. Non obstructive patterns were noticed in 16 kidneys 15 [patients], with down sloping curves during second time renograms in seven kidneys and flat second time renogram with drop of activity by> 50% in 9 kidneys. Obstructive patterns on dual time point [99m] TcMAG3 renography were noticed in 31 kidneys [29 patients]. Eleven kidneys [six patients] were false positive, since three patients had neurogenic bladder with no obstruction, two patients had long standing severe hydronephrosis with no obstruction and one patient had glomerulonephritis. Equivocal patterns were noticed in nine patients, four of them were turned to have significant obstruction, while five had no obstruction. Dual-time [99m] Tc-MAG3 diuretic renography can increase the efficiency in differentiating between obstructed and non-obstructed hydronephrosis compared to routine single time study

Impact of dual time point FDG PET imaging in the assessment of solitary pulmonary nodules

The aim of this study was to assess the diagnostic potential of [18]F-FDG Positron Emission Tomography imaging in the evaluation of patients with solitary pulmonary nodules, by comparing the diagnostic criteria in single time point imaging method to two different diagnostic criteria in dual-time-point imaging. This retrospective study was conducted in the Hospital of the University of Pennsylvania, and data was collected and analyzed in the period from September 2005 to March 2006, from the pooled hospital studies for the last eight years. Two hundred sixty five patients were included [161 men, 104 women, age range: 41-92 years]. All had solitary pulmonary nodules on computed tomography, and the diagnosis was confirmed by biopsy or by follow up computed tomography. All 265 patients underwent whole body FDG PET scan, and 255 of them had PET scan two time points. The maximum standardized uptake values of nodules were calculated for both time points. On single time point imaging we set the maximum standardized uptake value of 2.5 as a cutoff criterion for malignancy. On dual time point imaging, first criterion of malignancy was set as any increase in the maximum SUV from the first to second time point. The second criterion was set as either no change or increase in the maximum standardized uptake value between the two time points. Sensitivity, specificity and accuracy were calculated for the three methods by using the biopsy results and clinical follow up as gold standard. Biopsy and follow-up revealed 72 patients with malignant lung nodules, whereas 193 patients had benign nodules. Single time point imaging with a threshold maximum standardized uptake value of 2.5 had a sensitivity, specificity and accuracy of 63%, 92% and 85% respectively. On dual-time-point imaging, for the initial criterion for malignancy, the sensitivity, specificity and accuracy were 81%, 95% and 91% respectively. On dual time point imaging, for the second criterion for malignancy, the sensitivity, specificity and accuracy were 92%, 93%, and 92% respectively. Dual-time-point FDG PET imaging using both criteria has higher sensitivity, specificity and accuracy compared to single time imaging. Dual-time-point FDG PET imaging should be included in the clinical workup of patients with pulmonary nodule

Diagnostic value of 99m Tc-labeled red blood cell single photon emission tomography for the diagnosis of liver hemangiomas

Technetium-99m red blood cell scintigraphy is a very specific method to differentiate a hemangioma from other hepatic masses. The purpose of this study is to evaluate the efficacy of planar scintigraphy and single photon emission computed tomography Technetium-99m-labeled red blood cell in the investigation of suspected hepatic cavernous hemangioma. The study group consisdered of one hundred and five patients, 62 females [59%] and 43 males [41%], between 23-69 years of age [mean age of 41]. These patients were evaluated for liver masses found on ultrasound. The final diagnosis was made after liver biopsy or aspiration cytology in 26 patients and after folow-up by maintaining stable clinical course ranging for one year with no changes in the size or appearance of the lesion on ultrasound in 79 patients. One hundred and thirty two lesions were found; hemangioma in 96 patients and non-hemangiomatous lesions in 36 patients. Planar[99m] Tc-red blood cell showed sensitivity and specificity of 67% and 100% respectively, while [99m] Tc-red blood cell-single photon emission computed tomography showed sensitivity and specificity of 81%, 97% respectively. The use of single photon emission computed tomography showed better sensitivity value than PS from hemangiomas < 2.5 cm [61% for single photon emission computed tomography versus 24% for planar scintigraphy]. Tc-99m RBC scintigraphy is a simple, noninvasive and accurate technique in the detection of hepatic hemangioma. It can distinguish from other hepatic lesions. Single photon emission computed tomography is superior to planar imaging in the detection of small hemangioma and should be performed whenever planar imaging fails to show the lesion by 2 hours. Lesions less than 1.1 cm cannot be detected by Tc-99m red blood single photon emission computed tomography because they are beyond the limit of spatial resolution of the gamma camera used