Combined use of virtual monochromatic images and projection-based metal artifact reduction methods in evaluation of total knee arthroplasty.

OBJECTIVES: To evaluate the effect of the combined use of virtual monochromatic imaging (VMI) and projection-based metal artifact reduction (PB-MAR) methods on further artifact reduction and image quality in total knee arthroplasty (TKA) patients. METHODS: Fifty-seven knee joints from 36 patients who had a previous history of TKA for bilateral or unilateral knee joints were included in this study. Four sets of images were compared between non-MAR, PB-MAR, VMI, and VMI + PB-MAR. For quantitative analysis, the area, mean attenuation, artifact index (AI), and contrast-to-noise ratio (CNR) were calculated for each protocol. Regarding qualitative analysis, overall artifact and depiction of soft tissue and bony structure were compared using relative visual grading analysis. RESULTS: In the femoral region, the VMI + PB-MAR protocol showed the best MAR performance in quantitative measures including area, mean attenuation, and AI (p < .001). However, MAR protocols with VMI showed significantly lower CNRs than did the protocols without VMI in the tibial region (p < .001). On qualitative analysis, VMI + PB-MAR also showed fewer overall artifacts than did the other two MAR protocols. Soft tissue was best depicted in VMI + PB-MAR protocol, and PB-MAR showed the best performance for the depiction of bony structure (p < .001). CONCLUSIONS: The combined use of VMI and PB-MAR showed better MAR performance than did PB-MAR or VMI alone. In areas with severe metal artifacts, the VMI + PB-MAR and PB-MAR protocols were useful for the evaluation of soft tissue and bone structure, respectively. KEY POINTS: • The combination of artifact reduction methods is effective in reducing metal artifacts in CT. • Soft tissue was best depicted in the combined protocol of projection- and dual-energy-based methods, and projection-based protocol showed the best performance for the depiction of bone structure in case of severe metal artifacts.

Imaging features of left ovarian and renal venous aneurysms: two case reports and literature review.

Venous aneurysms rarely occur in the visceral veins. We report two extremely rare cases of venous aneurysms, one of the ovarian vein and the other one of the renal vein. The aneurysms were depicted on grayscale and color Doppler ultrasonography as anechoic saccular structures with compressibility and blood flow. Pulsed Doppler ultrasonography showed venous flow. Contrast-enhanced computed tomography showed aneurysmal venous dilatation. We diagnosed left ovarian and renal venous aneurysms. We also review the clinical presentation and implications of visceral venous aneurysms.

Multidetector computed tomography of iliac vein variation: prevalence and classification.

PURPOSE: To determine the prevalence of iliac venous variations and to classify the variations using multidetector computed tomography (MDCT). MATERIALS AND METHODS: MDCT images of 2,488 patients were retrospectively reviewed. Iliac venous variations were documented and classified with regard to internal iliac vein (IIV) drainage patterns, the presence of interiliac communicating veins and inferior vena cava (IVC) anomalies associated with iliac venous variations. The variation prevalence rates were analyzed and calculated. RESULTS: The incidence of iliac venous variations was 20.9%, and these were classified into eight types: normal, 79.1% (type 1); high joining of the IIV to the ipsilateral external iliac vein, 8.7% (type 2); the IIV joining to the contralateral common iliac vein (CIV), 2.3% (type 3); IIVs forming a common trunk, 0.9% (type 4); communicating vein from the IIV to the contralateral CIV or IIV, 7.8% (type 5); double IVC with or without a connecting vein, 0.9% (type 6); left IVC, 0.1% (type 7); and fenestration of the CIV, 0.4% (type 8). There were subtypes which varied according to right- or left-side variation and the status of smaller connecting veins. No statistical difference in the prevalence rate was found between men and women (p = 0.365). CONCLUSIONS: Iliac venous variations are frequently seen on MDCT and can be classified into 8 types.

Unilateral renal oncocytosis and combined hybrid tumor: a case report and review of the literature.

Renal oncocytosis is a very rare cause of multiple renal masses. Imaging features of renal oncocytosis and combined tumors have rarely been reported. Here, we describe a case of unilateral left renal oncocytosis and a combined hybrid tumor between chromophobe renal cell carcinoma and oncocytoma, which were depicted on CT and MR imaging as multiple enhancing solid masses with one dominant mass. Additionally, we reviewed the literature.

Right double inferior vena cava associated with retrocaval ureter: computed tomographic findings in two cases.

Two cases of right double inferior vena cava (RDIVC) were observed on computed tomography. In one case, the duplicated IVCs were both located to the right of the abdominal aorta and were nearly on the same coronal plane. In the other case, the right IVC showed partial duplication. The right ureter coursed posterior to the lateral IVC, then emerged between the duplicated IVC in both cases. The findings from the two cases presented in this report showed novel anatomical differences, likely attributable to different embryologic processes, as compared to previously reported cases of RDIVC.