Iodine quantification and detectability thresholds among major dual-energy CT platforms.

OBJECTIVES: To estimate the minimum detectable iodine concentration on multiple dual-energy CT (DECT) platforms. METHODS AND MATERIALS: A phantom containing iodine concentrations ranging from 0 to 10 mg ml-1 was scanned with five dual-energy platforms (two rapid kilo volt switching (r-kVs), one dual source (DS), one sequential acquisition and one split-filter). Serial dilutions of 300 mg ml-1 iodinated contrast material were used to generate concentrations below 2 mg ml-1. Iodine density and virtual monoenergetic images were reviewed by three radiologists to determine the minimum visually detectable iodine concentration. Contrast-to-noise ratios (CNRs) were calculated. RESULTS: 1 mg mL-1 (~0.8 mg mL-1 corrected) was the minimum visually detectable concentration among the platforms and could be seen by all readers on the third-generation r-kVs and DS platforms. CONCLUSIONS: At low concentrations, CNR for monoenergetic images was highest on the DS platform and lowest in the sequential acquisition and split-filter platforms. ADVANCES IN KNOWLEDGE: The results of this study corroborate previous in vivo estimates of iodine detection limits at DECT and provide a comparison for the performance of different DECT platforms at low iodine concentrations in vitro.

LOWER RATES OF RESIDUAL/RECURRENT DISEASE IN PATIENTS WITH INCIDENTALLY DISCOVERED THYROID CARCINOMA.

OBJECTIVE: Incidentally discovered thyroid cancers (IDTCs) have contributed to the rapid rise in thyroid cancer incidence over the past 20 years. Since death rates from thyroid cancer are not increasing, we hypothesized that IDTCs are less aggressive compared to clinically apparent thyroid cancer (CATC). METHODS: A retrospective study of patients and tumor characteristics of IDTCs and their rates of residual/recurrent (R/R) disease were determined at a median follow-up of 27 months in the setting of a large academic medical center. Patient analysis groups (IDTC [n = 46] and CATC [n = 126]) were based upon how the cancer was initially discovered. Patients were followed clinically and by biochemical testing and ultrasonography. We also compared time to progression between these groups. RESULTS: Patients in the two groups had similar demographic and tumor characteristics. At the close of the study, R/R status in the IDTC group was 6.7%, compared to 20.8% in the CATC group (P = .04). Of the 28 individuals in our overall cohort who had R/R disease, 3 were from the IDTC group and 25 were from the CATC group (P = .04). All three of the IDTC recurrences occurred within the first 6 months of follow-up. Using Kaplan-Meier analysis, there was a nonsignificant trend for longer progression-free survival in the IDTC group (P = .08). CONCLUSION: Compared to CATC patients, IDTC patients have a significantly less aggressive course and a trend toward longer progression-free survival. If confirmed by further studies, it may be reasonable to subject them to less intense surveillance and more conservative therapeutic approaches. ABBREVIATIONS: CATC = clinically apparent thyroid cancers CT = computed tomography HMH = Houston Methodist Hospital IDTC = incidentally discovered thyroid cancer MRI = magnetic resonance imaging PET = positron emission tomography PTMC = papillary thyroid microcarcinoma R/R = residual/recurrent RRA = radioiodine remnant ablation Tg = thyroglobulin TgAb = anti-thyroglobulin antibody TSH = thyroid-stimulating hormone US = ultrasonography.

Concurrent angiomyolipoma and two oncocytomas in the same kidney.

We report on a rare case of synchronous angiomyolipoma (AML) and 2 oncocytomas (OCs) in the same kidney of a 73-year-old woman. During the course of a follow-up for a long-standing staghorn calculus in the left kidney, a 4-cm right suprarenal mass and a small solid nodule adjacent to a cyst in the midportion of the right kidney were radiographically discovered. A radical nephrectomy was performed. The suprarenal tumor was found to be an AML, and the small nodule was an OC (1.5 cm). An additional OC (0.8 cm) elsewhere in the right kidney was also identified. The coexistence of AML and other renal tumors is uncommon. Among reported cases, conventional renal cell carcinoma, possibly reflecting its higher incidence, has been the most common concurrent tumor with AML. Although only rare cases of simultaneous AML and OC have been reported in the literature, it appears that the proportion of OC among concurrent renal tumors with AML is higher than expected based on its frequency among all surgically resected renal neoplasms. Whether there is a pathogenetic association between AML and OC needs to be further investigated.