Alan H. Matsumoto

Gadolinium enhanced MR imaging of vascular stents.

The feasibility of obtaining in-plane magnetic resonance (MR) vascular images in the presence of a vascular stent and the value of infusing an MR contrast agent during imaging was assessed. Coronal and sagittal MR imaging at 1.5 T was performed on six dogs with tantalum aortic stents using single-section gradient echo (GRE) imaging and MR angiography techniques before and during intravenous infusion of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). In-plane gradient echo (GRE) imaging and MR angiography clearly showed flow within the stented vessel as increased signal, with a minimum amount of stent-related artifact. Infusion of Gd-DTPA significantly increased the signal of flowing blood and allowed for better delineation of the stented aortic lumina. Our results demonstrate that in-plane GRE imaging and MR angiography can potentially be used as noninvasive methods for evaluating vascular patency in the presence of MR-compatible endovascular devices. In addition, Gd-DTPA infusion during MR vascular imaging clearly enhances the definition of flowing blood in the lumina of stented vessels.

Evaluation of ferromagnetism and magnetic resonance imaging artifacts of the Strecker tantalum vascular stent

A woven tantalum vascular stent (Strecker stent) was tested for ferromagnetism at 4.7 T and underwent magnetic resonance imaging (MRI)in vitro andin vivo at 1.5 T to evaluate the production of magnetic susceptibility artifacts. No ferromagnetism was detected. Spin-echo, phase reconstruction, and gradient echo images revealed a low level of susceptibility artifacts bothin vitro andin vivo. Our findings demonstrate the feasibility of using MRI to evaluate blood vessels noninvasively following tantalum stent placement.

Technical note: Superselective Gelfoam embolotherapy using a highly visible small caliber catheter

A new, highly visible and flexible 3F catheter has become available for superselective catheterization and embolization. We describe the first reported series of cases in which this catheter was used for superselective Gelfoam embolization of bleeding visceral arteries.

Percutaneous nephrostomy in infants.

We reviewed our experience with percutaneous nephrostomy placement in children less than one year of age during a five-year period. Placement was successful in 8 of 9 cases. There were no complications. The procedure favorably altered the outcome for each patient and was useful for reversing azotemia prior to surgical intervention for repair of an obstructed system (2 renal units), for providing drainage of pyonephrotic kidneys (3 renal units), for demonstrating inadequate recovery of renal function after relief of obstruction (2 renal units), and for replacing a surgically placed nephrostomy that was dislodged (1 renal unit). Our experience has encouraged us to accept the technique, and we believe that it is a valuable nonsurgical alternative that should be available to urologists managing infants with urinary tract pathology.

Percutaneous nephrostomy drainage in the management of neonatal anuria secondary to renal candidiasis

We report a case of anuria in a premature neonate secondary to bilateral ureteropelvic junction obstructions related to Candida bezoars. Percutaneous decompression and drainage of both kidneys contributed significantly to the successful management of renal candidiasis in this patient. A review of the literature is presented.

Isolated popliteal vein entrapment

We present two cases of isolated popliteal vein entrapment caused by the lateral head of the gastrocnemius muscle confirmed by both venography and magnetic resonance imaging of the knee.

The use of double guidewires through a single vascular sheath for obtaining profunda femoris arterial access: Technical note

We describe a double guidewire/single vascular sheath technique that facilitates dilatation of stenotic lesions within both the superficial femoral and profunda femoris arteries following a single antegrade common femoral arterial puncture. Such a technique prevents inadvertent loss of vascular access during maneuvers to catheterize the profunda femoris artery or the superficial femoral artery. Angioplasty within the superficial femoral artery with simultaneous safety-wire placement within the profunda femoris artery has been described previously, but we present, in this technical note, successful profunda femoral angioplasty with the safety wire within the superficial femoral artery.

Triple catheter aortoiliac angioplasty in a patient with a horseshoe kidney: Technical note

A method is described for protecting a nonstenotic anomalous artery to the left-lower pole of a horseshoe kidney that originated from a stenotic left common iliac artery. Using a triple catheter technique, injury to this anomalous renal artery was prevented while using “kissing balloons” to dilate bilateral proximal common iliac artery stenoses.