Technical report: A low cost technique for vessel sizing in angioplasty

Accuracy of pre-interventional computed tomography angiography post-processing software and extravascularly calibrated devices to determine vessel diameters: comparison with an intravascularly located calibrated catheter

Background Accurate vessel sizing might affect treatment outcome of endovascular therapy. Purpose To compare accuracy of peripheral vessel diameter measurements using pre-interventional computed tomography angiography post processing software (CTA-PPS) and extravascularly located calibrated devices used during digital subtraction angiography (DSA) with an intravascular scaled catheter (SC). Material and Methods In 33 patients (28 men, mean age = 72 ± 11 years) a SC was used during DSA of the femoro-popliteal territory. Simultaneously, one scaled radiopaque tape (SRT) was affixed to the lateral thigh, one scaled radiopaque ruler (SRR) was positioned on the angiography table. For each patient, diameters of five anatomic landmarks were measured on DSA images after calibration using different scaled devices and CTA-PPS. Diameters were compared to SC (reference) and between groups of non-obese (NOB) and obese (OB) patients. Results In total, 660 measurements were performed. Compared to the reference, SRT overestimated the diameter by 1.2% (range = -10-12, standard deviation [SD] = 4.1%, intraclass correlation coefficient [ICC] = 0.992, 95% confidence interval [CI] = 0.989-0.992, P = 0.01), the SRR and CTA-PPS underestimated it by 21.3% (range = 1-47, SD = 9.4%, ICC = 0.864, 95% CI = 0.11-0.963, P = 0.08) and 3.2% (range = 17-38, SD = 9.7%, ICC = 0.976, 95% CI = 0.964-0.983, P = 0.01), respectively. Underestimation using the SRR was greatest in the proximal superficial-femoral artery (31%) and lowest at the P2 level of the popliteal artery (15%). In the NOB group, diameter overestimation of the SRT was 0.8% (range = 4-7, SD = 4.2%, B = 0.071, 95% CI = 0.293-0.435, P = 0.08) compared to the OB group of 1.6% (range = -7-4, SD = 2.9%, B = 0.010, 95% CI = 0.474-0.454, P = 0.96). Diameter underestimation of the SRR was 17.3% (range = 13-21, SD = 3.1%, B = 0.946, 95% CI = 0.486-1.405, P = 0.002) in the NOB group, 23.3% (range = 11-36, SD = 6.6%, B = 0.870, 95% CI = 0.268-1.472, P = 0.007) in the OB group. Conclusion For calibrated measurements SRT and CTA-PPS prove accurate compared to the reference, while SRR does not. Obesity has a significant impact on underestimation of diameter if SRR is used.

Dangerous advances in measurements from digital subtraction angiography: when is a millimeter not a millimeter?

Aneurysms need accurate millimeters (mm). Direct millimeters were lost with digital subtraction angiography (DSA) years ago, with measurements in pixels. Advances in DSA can now give inherent millimeters. The Cerecyte aneurysm coiling trial's angiographic core lab assesses images from compact disc (CD). External fiducials for millimeter calibration are required. Of 25 cases with two 10 mm fiducials, near and far from the intensifier, the midline mean is between 9 "mm" to 15 "mm". Yet 10 mm must be 10 mm. This variance is potentially dangerous. Proprietary software seems to prohibit calibration transfer via CD to another vendor's system.

Treatment of refractory post-transjugular portosystemic stent-shunt encephalopathy: a novel case of stent luminal reduction

Encephalopathy is a significant complication of transjugular intrahepatic portosystemic stent-shunt (TIPSS). The majority respond to medical treatment but a proportion prove recalcitrant to conservative measures and eventually require some modulation of shunt blood flow in order to ameliorate their symptoms. This is particularly relevant in patients for whom TIPSS has been performed as a rescue procedure and are not suitable for liver transplantation (OLT). We describe a novel approach to the reduction of the diameter of the stent-shunt in TIPSS in an encephalopathic patient. This involved the creation of a waist around a standard covered stent and its subsequent introduction into a pre-existing TIPSS. This proved to be a successful procedure resulting in the alleviation of the patient's encephalopathy.

Three-dimensional rotational angiography in peripheral endovascular interventions

PURPOSE

To demonstrate the feasibility and applicability of 3-dimensional rotational angiography (3D-RA) in the assessment of candidates for endovascular treatment of occlusive or aneurysmal arterial disease.

TECHNIQUE

In 3D-RA, a continuous rotation of the fluoroscopic tube around the region of interest is made while intra-arterial contrast is continuously infused. The area of interest is placed in the isocenter in both frontal and lateral planes. Images are acquired at a rate of 12.5 frames per second at a rotation speed of 30 degrees per second. Injection protocols are adjusted according to the anatomical location. The acquisition takes 8 seconds and yields 100 contrast-enhanced cinefluoroscopic images that are automatically reconstructed within 5 minutes to yield a 3D volume that can be rotated and viewed in any direction. Measuring the diameter of the target vessel and length of the lesion can be performed in the same session. An initial evaluation of this technique in 101 patients with known peripheral vascular disease yielded diagnostically adequate images preprocedurally while adding a maximum of only 10 minutes to the endovascular procedure: 5 minutes for reconstruction and another 2 to 5 minutes for measurements, which were made without difficulty in all cases. 3D-RA aided in selection of the optimal fluoroscopic tube angulation for the endovascular procedures and provided assessment of the interventional results comparable to angiography.

CONCLUSIONS

Our preliminary experience suggests that 3D-RA appears to be a valid tool in the pre- and periprocedural assessment of patients treated endovascularly for both aneurysmal and occlusive peripheral arterial diseases.