MR-guided breast biopsy using an active marker: a phantom study.

PURPOSE: To evaluate the advantages of using an active marker (active micro coil) for MR-guided breast biopsy procedures. MATERIALS AND METHODS: An add-on breast biopsy guidance device used with a standard breast coil was equipped with an active marker. The marker's position was determined with a dedicated MRI sequence. In combination with custom software, the biopsy planning process was reduced basically to defining the target in the diagnostic MR images. Automatic control scans verified the settings of the biopsy guidance device. To measure the targeting accuracy, x-ray control of the needle placement was performed in phantoms containing 36 small titanium cylinders. The reliability of the procedure was evaluated in 24 core needle biopsies on phantoms. Workflow enhancements were analyzed. RESULTS: The root mean square deviation of the needle position from the target perpendicular to the needle axis was 1.25 mm, in three-dimensions it was 1.35 mm. All targets were sampled successfully. The duration of a phantom biopsy was nine minutes. CONCLUSION: The use of an active marker can offer advantages for MR-guided breast biopsies in terms of handling and procedure time as well as accuracy.

Value of fat-suppressed PD-weighted TSE-sequences for detection of anterior and posterior cruciate ligament lesions--comparison to arthroscopy.

OBJECTIVE: To evaluate fat-suppressed (FS) proton-density-weighted (PDw) turbo spin-echo (TSE) magnetic resonance imaging for the detection of anterior and posterior cruciate ligament lesions in comparison to arthroscopy. MATERIALS AND METHODS: In a prospective study 31 knee joints were imaged on a 1.5T MR scanner (Vision, Siemens, Erlangen) prior to arthroscopy using following sequences: (a) sagittal FS-PDw/T2w TSE (TR/TE: 4009/15/105 ms); (b) sagittal PDw/T2w TSE (TR/TE:3800/15/105 ms). Further imaging parameters: slice thickness 3mm, FOV 160 mm, matrix 256 x 256. A total of 62 anterior and posterior cruciate ligaments (ACL/PCL) were evaluated, standard of reference was arthroscopy. Sensitivity, specificity, positive (ppv) and negative predictive value (npv) and accuracy were calculated. RESULTS: Twenty-one cruciate ligament ruptures were detected in arthroscopy, 19 ACL- and 2 PCL-ruptures (on MRI 34/124, 25/62 ACL, 9/62 PCL lesions). For all four sequences in the 31 patients with arthroscopic correlation sensitivity, specificity, ppv, npv and accuracy were 86%, 98%, 95%, 93% and 94% for detection of tears, and 84%, 100%, 100%, 80% and 90% for ACL-ruptures respectively. The two PCL-ruptures were true positive in all sequences, one intact PCL was diagnosed as torn (false positive). CONCLUSIONS: Fat-suppressed PDw/T2w TSE-MR sequences are comparable to PDw TSE sequences for the detection of ACL/PCL-lesions.

Low-profile stent placement with the monorail technique for treatment of renal artery stenosis: midterm results of a prospective trial.

PURPOSE: To determine feasibility, safety, and midterm patency of a monorail balloon stent device for the treatment of renal artery stenosis (RAS). MATERIALS AND METHODS: During a period of 30 months, 47 patients (with severe hypertension, n=45; renal insufficiency, n=20) with 50 cases of RAS and indications for stent implantation (calcified ostial lesion, n=41; insufficient percutaneous transluminal angioplasty, n=6; dissection, n=3) were enrolled into the prospective evaluation. After predilation, 59 stents (Rx-Herculink 4 mm, n=2; 5 mm, n=19; 6 mm, n=35; 7 mm, n=3) were implanted under manometer control with use of the long-sheath technique (5 F; 6 F for 7-mm stents) via a femoral (n=44) or transbrachial approach (n=6). Parameters of hypertension and renal insufficiency were determined before and after the procedure and for a maximum of 18 months. Restenosis rate was determined with color duplex ultrasonography. RESULTS: Renal artery stent placement (mean diameter, 5.7 mm; mean length, 16 mm) was technically successful in all cases (100%). Mean blood pressure and serum creatinine level decreased from 177/93 mm Hg to 145/78 mm Hg and from 1.8 mg/dL to 1.5 mg/dL, respectively. Within 48 hours after the implantation, acute occlusions occurred in two patients, supposedly triggered by cholesterol embolization. Primary and primary assisted patency rates were 87% and 92% at 6 months and 75% and 84% at 18 months. CONCLUSIONS: Renal artery stent placement with the rapid-exchange monorail system is a safe procedure with promising patency rates. In combination with the long-sheath technique, adequate control of stent deployment is guaranteed during the entire intervention. The low profile of the device facilitates the use of small sheaths (5 F) to minimize access-site complications.

Bilateral leg ischemia due to descending aortic dissection: combined treatment with femoro-femoral cross-over bypass and unilateral aorto-iliac stenting.

We report a case of aorto-iliac occlusion due to descending aortic dissection treated initially with femoro-femoral cross-over bypass and secondarily with unilateral aorto-iliac stenting because of progression of the dissection. A 75-year-old man presented with acute ischemia of the right leg. CT revealed occlusion of the right iliac artery due to descending aortic dissection with a clotted false lumen. Three days after femoro-femoral cross-over bypass, ischemia of both legs developed and angiography demonstrated occlusion of the infrarenal aorta and left common iliac artery. Two overlapping stents were deployed in these vessel segments. Completion angiography confirmed successful recanalization with adequate distal flow and good patency of the cross-over bypass. Peripheral pulses were restored and the patient's symptoms were alleviated. Combined treatment with cross-over bypass and endovascular recanalization may be considered as a viable alternative to open aortic surgery in selected cases of complicated aorto-iliac dissection with bilateral leg ischemia.