Plaque Placement Research Articles

The treatment of choroidal melanoma with 198Au plaque brachytherapy

Background: Seventy-nine consecutive patients with primary choroidal melanoma were treated with 198Au plaque brachytherapy at the British Columbia Cancer Agency (BCCA) between 1992 and 1998 with perioperative ultrasound to confirm plaque placement. Seventy-seven of the 79 patients were analyzable for this study. Results: Five year actuarial disease specific survival, enucleation free survival, and local control are 95, 94, and 98%, respectively. There were four melanoma related deaths, all secondary to liver metastases. Conclusions: The BCCA experience in selected patients with choroidal melanomas treated with 198Au plaque brachytherapy has resulted in excellent survival and local control with minimal significant toxicity while preserving the globe. Our results using 198Au seeds are comparable to other series using 125I, 60Co, and 106Ru at other centers.

Intraoperative echographic localization of iodine-125 episcleral plaque for brachytherapy of choroidal melanoma

PURPOSE: To report intraoperative echographic localization of iodine-125 episcleral plaque for brachytherapy of choroidal melanoma. METHODS: In a retrospective study, 117 eyes with medium-sized choroidal melanoma in 117 patients not participating in the Collaborative Ocular Melanoma Study underwent iodine-125 episcleral plaque radiotherapy with intraoperative echographic verification of plaque placement between January 1992 and December 1998 at the Bascom Palmer Eye Institute. RESULTS: After initial plaque placement using standard localization techniques, intraoperative echography demonstrated satisfactory tumor–plaque apposition in 76% of eyes (89 of 117). In the 28 eyes (28 of 117, 24%) that required repositioning of the plaque, the extent of misplacement was less than 1 mm in 10 eyes, 1.1 to 3.0 mm in six eyes, and greater than 3 mm in eight eyes. Two eyes had tilting of the plaque, and in two additional eyes, although the plaque covered all tumor margins, the centration was considered suboptimal. Repositioning was necessary in 1 eye with an anteriorly located tumor (1 of 13, 7.7%) and in 20 eyes with peripapillary or posterior pole tumors (20 of 67, 26.3%). Anteriorly located tumors required plaque repositioning significantly less frequently than did posteriorly located tumors ( P = .041). Misalignment involved one tumor margin in 23 eyes and two margins in five eyes. The most commonly misaligned margins were the lateral (35%) and posterior margins (26%). In no case was an anterior marginal misalignment documented. At a mean follow-up of 37 months, no tumor-related death or metastatic disease was noted. Two of the 117 patients (1.7%) had local tumor recurrence and underwent enucleation. CONCLUSIONS: Intraoperative echography is an effective adjunct for localization and confirmation of tumor–plaque relationship. This technique facilitates the identification and correction of suboptimal plaque placement at the time of surgery, potentially minimizing treatment failures.

Peyronie's disease--incision and dorsal vein grafting combined with contralateral plication in straightening the penis.

To evaluate the effectiveness of incisions of Peyronie's plaque and vein grafting combined with contralateral plication to straightening the penis. Twenty-four patients with Peyronie's disease were treated surgically with a vein patch grafting technique to correct penile curvature. Median penile deviation was 70 degrees (range 60-90 degrees ), in 1 patient curvature was 30 degrees and all were unable to have normal sexual intercourse. The deep dorsal vein was excised and opened longitudinally. Transverse relaxing incisions about 1-2 cm long were made on the plaques at the point of maximal curvature, then, two other lateral incisions were made on both ends at 3 and 9 o'clock. The endothelial side of the harvested vein was placed in contact with the cavernous tissue to cover the defect created. Application of the contralateral surface of the tunica albuginea was performed in 21 cases to straighten the penis. After a median follow-up of 24 months, 19 patients were able to perform sexual intercourse, 3 patients who required intracavernous injection to maintain erection presented pre-operative adverse factors affecting erectile function. One patient returned to baseline pre-operative curvature. Twelve patients reported penile shortening, although only 5 patients were concerned about it. None of the patients permanently lost sensation in the glans of the penis. Palpable knots on the site of plication were reported in 5 patients. Plaque incision and placement of a deep dorsal vein patch graft, combined with contralateral corporeal plication, is a relatively simple, safe and effective alternative to correct angulations greater than 60 degrees.

Three-dimensional ultrasonography of choroidal melanoma: localization of radioactive eye plaques.

To evaluate the use of 3-dimensional (3D) ultrasonography for the localization of episcleral eye plaques during the treatment of choroidal melanomas. A series of 13 patients with choroidal melanoma were treated with radioactive palladium 103 seeds affixed into gold eye plaques. During surgery, 3D ultrasonography was performed with a commercially available system to evaluate the relative position of radioactive plaques secured beneath their intraocular tumors. This system consists of an automated, rotating, handheld, B-scan ultrasonographic probe operating at 10 MHz, a personal computer, and 3D imaging software. We measured the margins of the plaque extending beyond the tumor and the distance between the radioactive seeds and the tumor apex. We also evaluated the relationship between the plaque edge, the episclera, and the tumor's edges. While the plaques were well centered over the tumor in all cases, the plaque margins around the tumor were found to be variably sized. When comparing measurements taken at the time of plaque insertion with those taken at the time of plaque removal, we noted changes in the apical tumor height and in plaque centration. In the 1 patient with a juxtapapillary tumor, the posterior margin of the plaque was found to be displaced away from the sclera, or "tilted." Three-dimensional ultrasonography offers a new method for ophthalmic plaque localization. Unique perspectives can be visualized through the use of computer-aided 3D reconstructions that permit the assessment of the relative position of the plaque to the optic nerve and the measurement of the distance between the in vivo radioactive seed and the tumor apex. Our experience suggests that when compared with 2-dimensional ultrasonography, 3D ultrasonography offers new capabilities that can be used to improve plaque placement and radiation dose calculations.

INTRAOPERATIVE ECHOGRAPHIC LOCALIZATION OF IODINE 125 EPISCLERAL RADIOACTIVE PLAQUES FOR POSTERIOR UVEAL MELANOMA

Plaque radiotherapy has been reported to have a higher relapse rate than charged-particle radiotherapy for posteriorly located uveal melanomas, which also are more technically difficult to localize accurately. The authors used intraoperative echography in patients with posterior uveal melanoma to determine the rate of inaccurate localization of iodine 125(125I) episcleral plaques using standard localization techniques. The authors reviewed the records of 29 consecutive patients with medium-sized posterior uveal melanomas who underwent 125I episcleral plaque radiotherapy with intraoperative echographic verification of plaque placement. After careful plaque placement using standard localization techniques, 4 of 29 plaques (14%) did not cover at least one tumor margin. All four of these plaques were associated with posterior tumors with at least one margin posterior to the temporal arcades. Two (7%) additional juxtapapillary plaques were displaced away from the sclera by the optic nerve. In all six cases, it was possible to immediately reposition the plaque to achieve coverage of all tumor margins. Placement of 125I episcleral radioactive plaques for posteriorly located uveal melanomas using standard localization techniques occasionally results in suboptimal plaque positioning. Intraoperative echography can identify plaques that are localized poorly and allows immediate adjustment to achieve optimal plaque positioning.

Long-term Followup of Treatment of Peyronie's Disease with Plaque Incision, Carbon Dioxide Laser Plaque Ablation and Placement of a Deep Dorsal Vein Patch Graft

Numerous surgical therapies have been used for Peyronie's disease in patients who maintain potency. We report on incision and carbon dioxide laser ablation of Peyronie's plaque combined with a deep dorsal vein patch graft in the treatment of 6 men (mean age 57 years). The chief indication for surgery was curvature interfering with intromission, with voiding difficulty being a secondary indication as well. Long-term followup (mean 31 months) was available in 6 men, each of whom was potent preoperatively. Potency was preserved in all men, and 5 described significant improvement in penetration and curvature. In 1 patient the curvature returned to preoperative levels. Each patient reported a subjective shortening of the penis from one-quarter to 1 inch but no case was functionally debilitating. We describe this technique, which to our knowledge has been reported previously by only 1 group with 18 patients, and conclude that it may be used with successful preservation of potency and restoration of intercourse in the treatment of Peyronie's plaques.

Long-term Followup of Treatment of Peyronie's Disease with Plaque Incision, Carbon Dioxide Laser Plaque Ablation and Placement of a Deep Dorsal Vein Patch Graft

Long-term Followup of Treatment of Peyronie's Disease with Plaque Incision, Carbon Dioxide Laser Plaque Ablation and Placement of a Deep Dorsal Vein Patch Graft

Can a venous patch graft be a substitute for the tunica albuginea of the penis?

We describe our experience with plaque excision and placement of a venous patch graft. Sprague Dawley rats (n = 20) underwent excision of a wedge of tunica albuginea with the defect covered by a segment of detubularized femoral vein, endothelial side towards the cavernous tissue. Erectile function, as determined by the rise in intracavernous pressure with cavernous nerve stimulation (mean 54.0 ± 4.2cm. H20), was equal to that in a group of 10 intact age-matched controls (mean 46.9 ± 3.37cm. H20). Penile cross-sections stained with Hart’s elastic fiber stain or Trichrome stain revealed only minimal fibrosis in the region of the patch.In 3 dogs, a wedge of tunica was removed, and the defect was covered with a segment of detubularized deep dorsal vein. When sacrificed at 3 months, all animals had retained their erectile function with histologic evidence of minimal fibrosis.On the basis of histologic and functional data, the venous patch appears to be a reasonable alternative substance to those in common use.

Results of Combined Nesbit Penile Plication with Plaque Incision and Placement of Dacron Patch in Patients with Severe Peyronie’s Disease

We treated 9 men with severe curvature of the penis secondary to Peyronie’s disease with penile plication and a previously unreported technique of incision of the Peyronie plaque and placement of Dacron patch. All men were potent before penile straightening. At a mean followup of 17.5 months all men achieved good to excellent correction of the deformity and they have remained potent. One patient initially complained of numbness of the glans penis and decreased penile rigidity distal to the Dacron patch but potency returned and the numbness resolved.

Treatment of choroidal melanoma: MR imaging in the assessment of radioactive plaque position.

Verification of the position of an episcleral iodine-125 gold plaque in relation to underlying choroidal melanoma is essential during early radiation therapy to ensure accurate plaque placement and thus optimum dose delivery. The authors used magnetic resonance (MR) imaging to examine 15 patients with choroidal melanoma after plaque placement to assess tumor coverage. The relationship of the plaque to the tumor was well defined in all cases, including two tumors anterior to the ora serrata. MR imaging measurements of the plaques were within 1 mm of the actual plaque sizes, while tumor measurements were within 2 mm of the preoperative ultrasound estimations of tumor dimensions. Tumors as small as 3 mm thick were readily visualized with MR imaging. Associated subretinal effusion was demonstrated in seven cases.

Accuracy of Diagnosis of Choroidal Melanomas in the Collaborative Ocular Melanoma Study

In the 3-year period during which patients were enrolled into the Collaborative Ocular Melanoma Study, 413 eyes with clinical diagnoses of choroidal melanoma were examined histopathologically as of December 31, 1989. Four hundred eleven of these eyes were found to be diagnosed correctly. One eye, removed after preoperative external beam radiation, was found to have a hemangioma. The second eye, removed after radioactive iodine plaque placement, was described as a magnocellular nevus (melanocytoma) by four of the five pathologists on the Collaborative Ocular Melanoma Study Pathology Review Committee. The Collaborative Ocular Melanoma Study misdiagnosis rate of 0.48% is the lowest ever reported. The major challenge with regard to posterior uveal melanomas is no longer that of correct diagnosis but rather determination of the optimal treatment.

Magnetic resonance imaging of juxtapapillary plaques in cadaver eyes.

Adequate treatment of juxtapapillary melanomas with episcleral plaque brachytherapy using lower energy radiation sources may be difficult because of uncertainties regarding the relationship of the plaque to the optic nerve and tumour base. We obtained magnetic resonance images of a dummy plaque placed in a juxtapapillary location in cadaver specimens. Although it is possible to place a plaque in close association with the optic nerve sheath, a tissue barrier exists which may prevent actual contact between the plaque and nerve. Posterior tilting of the plaque may also occur. Because of these uncertainties regarding plaque placement, juxtapapillary melanomas should be considered a distinct subgroup when evaluating the efficacy of radioactive plaque brachytherapy in the treatment of choroidal melanoma.

MR technique for localization and verification procedures in episcleral brachytherapy

Spatial definition of an intraocular tumor and subsequent determination of the actual position of an implanted eye plaque are essential for adequate ocular brachytherapy treatment planning. However, a method for verification of the plaque placement which would provide required 3-dimensional information is not available at present. In addition, tumor localization procedures, including ultrasonography and CT techniques, cannot always offer the precision needed for 3-dimensional definition of an intraocular target. This communication describes a magnetic resonance imaging technique specifically developed for both localization and verification procedures. A 1.5 Tesla magnetic resonance scanner, spin-echo pulse sequence (echo time 30 msec, repetition time 700 msec), and commercially available surface coil were used to obtain a series of transverse, coronal, and sagittal images of a slice thickness of 3 mm. Usually, eight scans in each of the three planes were needed for adequate coverage of the orbit. The required patient set-up and data acquisition time did not exceed 40 minutes. With a data matrix size of 256 × 256 pixels and 13 cm field of view, localization and verification were accomplished with a precision of 0.5 mm. Our results suggest that the magnetic resonance imaging technique permits precise integration of diagnostic and therapeutic procedures, and in addition provides adequate data for accurate treatment planning. We conclude that magnetic resonance imaging is the preferred diagnostic technique for episcleral brachytherapy.

New Insights Into the Pathophysiology of Coronary Arteries by Epicardial High Frequency Echocardiography

Currently, the coronary angiogram remains the “gold standard” for the detection and quantification of coronary arterial disease. Clinical assessment of the arteriogram is usually based simply on the relative percent narrowing of the column of angiographic dye. However, such analysis oversimplifies and is not accurate for evaluating the extent and severity of coronary artery atherosclerosis. Recently a new generation of ultrasonic devices has become available for intraoperative evaluation of coronary arterial anatomy. These high frequency echocardiography transducers use 12 MHz probes. The transducer is placed directly over the epicardium during open heart surgery to evaluate the coronary artery. With this technique, demonstration of coronary artery anatomy, including wall and cross-sectional lumen, is available in vivo. We have undertaken numerous validation studies in vitro and in vivo of animal and postmortem human heart preparations to show that this technique can be used to accurately measure luminal area, luminal diameter, and wall thickness. Subsequently in patients intraoperatively the extent of atherosclerosis using luminal diameter to wall thickness (LD/WT) ratios was compared with the routine angiographic evaluation of coronary arterial disease using percent stenosis measurements. LD/WT ratios from arterial segments with no visible angiographic disease but with angiographic lesions elsewhere in the same coronary artery showed marked variability. The majority were in the range of LD/WT ratios of those segments where high frequency echocardiography recording was made at the site of “angiographic” disease. This indicates that in vivo atherosclerosis is more widespread than the angiogram predicts and underlies the difficulties of using percent stenosis angiographically to determine the extent and severity of coronary arterial disease. In a second study we have demonstrated that there is marked variability and eccentricity in coronary plaque geometry, luminal morphology, and placement of the residual lumen with respect to the atherosclerotic plaque. This eccentricity results in some relatively “normal” coronary wall at the site of maximum atherosclerosis, theoretically preserving the ability to vasodilate and vasoconstrict. Studies with high frequency echocardiography are underway to study the capability of arteries with atherosclerosis to vasodilate. We have evaluated atherosclerotic remodeling of coronary arteries and found that remodeling occurs in an attempt by the artery to preserve its residual luminal size during encroachment on the lumen by the atherosclerotic plaque. This is the first in vivo demonstration of this process in human coronary arteries. Coronary arterial bypass grafts have been evaluated in animal models and at the time of intraoperative coronary anastomoses to evaluate the adequacy of graft anastomoses and compare vein grafts with internal mammary grafts. This dynamic in vivo technique supports and extends information obtainable from pathologic studies. It contributes to our understanding of the pathologic anatomy of coronary arterial disease.

Ultrasound Determination of the Relationship of Radioactive Plaques to the Base of Choroidal Melanomas

There is an assumption that radioactive plaques placed at surgery are, and will remain, in proper relationship to the base of the tumor. The plaque dose is calculated based on this assumption. In fact, factors such as loose sutures, improper diameter estimations, pressure from adjacent rectus muscles, and intervening tissue (oblique muscles) can compromise this relationship. Ultrasound provides a practical method of imaging the tumor and plaque simultaneously. The authors have used postoperative ultrasound to monitor the accuracy of iodine-125 plaque placement in nine cases. Detection of eccentrically placed and malpositioned plaques provides valuable insight which can be used to refine surgical technique. Detection of plaque tilting by oblique muscles can serve as a basis for recalculating dosage. The relationship of plaque margins to vital ocular structures such as the optic nerve can also be determined by ultrasound.

An Inexpensive Fiberoptic Light Pipe to Aid in Placement of Episcleral Radioactive Plaques

Episcleral plaque placement requires accurate localization of choroidal melanomas. Available fiberoptic light pipes can be fashioned to become scleral markers and transilluminators. The equipment is available wherever posterior segment surgery is performed. Surgical technique and equipment modifications are described.

Computer-assisted intraoperative mapping of the entire ventricular epicardium in the wolff-parkinson-white syndrome

Intraoperative mapping with a hand-held, roving electrode requires a sustained rhythm lasting 5 to 10 minutes. To overcome this limitation, a computerized mapping system that records from 60 epicardial electrodes simultaneously was used to study 16 patients with Wolff-Parkinson-White syndrome. A sock containing 6 rows of electrodes arranged concentrically from base to apex was place over the ventricles. The total time from placing the sock to analyzing the most basal row of electrode recordings was 5 minutes. A 39 X 44-mm plaque containing 56 electrodes was than placed across the atrioventricular (AV) groove for detailed simultaneous mapping of the ventricle and atrium in the preexcited region identified from the most basal row of sock electrodes. During plaque placement and recording, the remaining sock recordings were analyzed and a complete isochronal epicardial map was drawn. The plaque recordings were then analyzed. This technique rapidly detects early activation at the AV groove as do other computer systems using only a band of electrodes around the AV groove. Also, complete epicardial mapping supplied important additional information. One patient with a posterior paraseptal accessory pathway had ventricular epicardial breakthrough below the strip recorded by the AV band. When more than 1 early activation site was present along the AV groove, complete maps allowed multiple pathways to be differentiated from normal activation fronts ascending from the bundle branches. Complete epicardial maps allowed the study of rapidly changing or short-lived electrical events including isolated premature impulses, initiation and termination of reciprocating tachycardia by pacing, entrainment and changing degrees of fusion created by pacing during reciprocating tachycardia, and ventricular responses during atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)