Mohamed Sayed

Technetium‑99m dimercaptosuccinic acid scan in evaluation of renal cortical scarring: Is it mandatory to do single photon emission computerized tomography?

Objectives: Renal cortical scintigraphy with technetium-99m (Tc-99m) dimercaptosuccinic acid (DMSA) is the method of choice to detect acute pyelonephritis and cortical scarring. Different acquisition methods have been used: Planar parallel-hole or pinhole collimation and single photon emission tomography (SPECT). This study compared planar parallel-hole cortical scintigraphy and dual-head SPECT for detection of cortical defects. Patients and Methods: We retrospectively reviewed 190 consecutive patients with 380 kidneys and 200 DMSA scans referred to rule out renal cortical scarring. The diagnoses were 52 vesicoureteric reflux, 61 recurrent urinary tract infection, 39 hydronephrosis, 20 renal impairment, and 18 hypertension. All patients were imaged 3 h after injection of Tc-99m DMSA with SPECT and planar imaging (posterior, anterior, left, and right posterior oblique views). For each patient, planar and SPECT images were evaluated at different sittings, in random order. Each kidney was divided into three cortical segments (upper, middle and lower) and was scored as normal or reduced uptake. The linear correlation coefficient for the number of abnormal segments detected between planner and SPECT techniques was calculated. Results: From 200 DMSA scans, 100 scans were positive for scar in SPECT images, from which only 95 scans were positive for scar in planner imaging. Out of the five mismatched scans, three scans were for patients with renal impairment and high background activity and two scans were for very small scars. No significant difference was seen in the average number of abnormal segments detected by planar versus SPECT imaging (P = 0.31). The average correlation coefficient between was high (r = 0.91 - 0.92). Conclusions: Tc-99m DMSA renal cortical scanning using SPECT offers no statistically significant diagnostic advantage over multiple views planar imaging for detection of cortical defect.Objectives: Renal cortical scintigraphy with technetium-99m (Tc-99m) dimercaptosuccinic acid (DMSA) is the method of choice to detect acute pyelonephritis and cortical scarring. Different acquisition methods have been used: Planar parallel-hole or pinhole collimation and single photon emission tomography (SPECT). This study compared planar parallel-hole cortical scintigraphy and dual-head SPECT for detection of cortical defects. Patients and Methods: We retrospectively reviewed 190 consecutive patients with 380 kidneys and 200 DMSA scans referred to rule out renal cortical scarring. The diagnoses were 52 vesicoureteric reflux, 61 recurrent urinary tract infection, 39 hydronephrosis, 20 renal impairment, and 18 hypertension. All patients were imaged 3 h after injection of Tc-99m DMSA with SPECT and planar imaging (posterior, anterior, left, and right posterior oblique views). For each patient, planar and SPECT images were evaluated at different sittings, in random order. Each kidney was divided into three cortical segments (upper, middle and lower) and was scored as normal or reduced uptake. The linear correlation coefficient for the number of abnormal segments detected between planner and SPECT techniques was calculated. Results: From 200 DMSA scans, 100 scans were positive for scar in SPECT images, from which only 95 scans were positive for scar in planner imaging. Out of the five mismatched scans, three scans were for patients with renal impairment and high background activity and two scans were for very small scars. No significant difference was seen in the average number of abnormal segments detected by planar versus SPECT imaging (P = 0.31). The average correlation coefficient between was high (r = 0.91 – 0.92). Conclusions: Tc-99m DMSA renal cortical scanning using SPECT offers no statistically significant diagnostic advantage over multiple views planar imaging for detection of cortical defect.

Increased 18F-FDG Uptake in the Posterior Ocular Bulb Is Associated with Brain Metastasis: A Retrospective Study

OBJECTIVE An observation of increased (18)F-FDG uptake in the posterior ocular bulb led us to the hypothesis that increased posterior ocular bulb uptake is likely abnormal and may indicate intracranial lesions. MATERIALS AND METHODS Fifteen healthy volunteers and 35 patients with lung carcinoma-14 without brain metastasis and 21 with brain metastases-were retrospectively studied. The individuals underwent whole-body PET/CT including the brain with low-dose and unenhanced CT. Two nuclear medicine physicians visually analyzed the posterior ocular bulb uptake of both eyes. Standardized uptake values (SUVs) in the posterior ocular bulb were compared among the study groups. A radiologist reviewed brain MRI scans for abnormalities in the ocular bulbs and orbits. RESULTS Visual interpretation showed normal FDG uptake at the posterior ocular bulb in 14 of the 15 healthy volunteers and 12 of the 14 (86%) patients without brain metastasis. Seventeen of the 21 (81%) patients with brain metastases showed increased uptake in the posterior ocular bulb. Visual interpretation showed no statistically significant difference between the healthy volunteers and patients without brain metastasis (p = 0.671). However, there was a significant difference between the patients with brain metastases and healthy volunteers as well as patients without brain metastasis (both, p < 0.001). High interrater agreement (kappa = 0.83) was noted. Brain MRI showed no abnormalities at the posterior ocular bulb in all study subjects. SUV results were inaccurate because of the intense tracer activity in the posterior orbit nearby. A good correlation between visually increased posterior ocular bulb uptake and the presence of brain metastasis was present (Cramers V = 0.61). CONCLUSION Visually increased FDG uptake along the posterior ocular bulb is an abnormal finding and may indicate intracranial structural abnormalities such as brain metastases.

Rate of thyroglossal duct remnant visualization after total thyroidectomy for differentiated thyroid carcinoma and its impact on clinical outcome of radioactive iodine (I-131) ablation.

Objectives: The rate and impact of thyroglossal duct remnant (TGDR) visualization in patients with hypothyroidism after total thyroidectomy for differentiated thyroid carcinoma (DTC) have not yet been fully determined. The aim of this study was to assess the rate of TGDR visualization in post total thyroidectomy whole body scan (WBS) for DTC and to evaluate its impact on the outcome of I-131 ablation. Methods: A total of 60 consecutive DTC patients (51 papillary thyroid Ca., and 9 Follicular thyroid Ca.), underwent total thyroidectomy, followed by WBS (using I-131 in 28 patients and I-123 in 32 patients), neck ultrasound (US), thyroglobulin (Tg) and Tg anti-bodies (TgAb) assay after 40 days and subsequent I-131 ablation. At 6 months later follow-up I-131 WBS, neck U/S, Tg and TgAb were performed following suspension of L-thyroxine for 1-month (thyroid stimulating hormone [TSH] >30 μIU/ml) in 53 patients and following recombinant human TSH stimulation in seven patients. Results: Of the studied 60 patients, 19/60 (31.7%) had a linear or focal radioactivity at the superior midline of the neck, suggesting TGDR (Group 1), and 41/60 (68.3%) had no uptake to suggest TGDR (Group 2). No significant difference regarding age, gender and histopathology between both groups. Neck US showed no evidence of thyroid tissue in the superior midline of the neck in both groups, and only a small or no residual thyroid tissue in patients of Group 1. There was a significant successful I-131 ablation rate among patients of group 1 compared to group 2 (79% in Group 1 vs. 41.5% in Group 2) (P = 0.007). Conclusions: Thyroglossal duct remnant visualization on WBS of hypothyroid subjects after total thyroidectomy suggests presence of only a small or no residual functioning thyroid tissue at the thyroid bed and can predict a good response to I-131 ablation.