A novel energy mapping approach for CT-based attenuation correction in PET.

PURPOSE: Dual-energy CT (DECT) is arguably the most accurate energy mapping technique in CT-based attenuation correction (CTAC) implemented on hybrid PET/CT systems. However, this approach is not attractive for clinical use owing to increased patient dose. The authors propose a novel energy mapping approach referred to as virtual DECT (VDECT) taking advantage of the DECT formulation but using CT data acquired at a single energy (kV(P)). For this purpose, the CT image acquired at one energy is used to generate the CT image at a second energy using calculated kV(P) conversion curves derived from phantom studies. METHODS: The attenuation map (µ-map) at 511 keV was generated for the XCAT phantom and clinical studies using the bilinear, DECT, and VDECT techniques. The generated µ-maps at 511 keV are compared to the reference derived from the XCAT phantom serving as ground truth. PET data generated from a predefined activity map for the XCAT phantom were then corrected for attenuation using µ-maps generated using the different energy mapping approaches. In addition, the generated µ-maps using the above described methods for a cylindrical polyethylene phantom containing different concentrations of K(2)HPO(4) in water were compared to actual attenuation coefficients. Likewise, CT images of five clinical whole-body studies were used to generate µ-maps using the various energy-mapping approaches were compared with µ-maps acquired at 511 keV using (68)Ge/(68)Ga rod sources for the clinical studies. RESULTS: The results of phantom studies demonstrate that the proposed method is more accurate than the bilinear technique. All three µ-maps yielded almost similar results for soft and lung tissues whereas for bone tissues, the DECT and the VDECT methods produced a much smaller mean relative difference (3.0% and 2.8%, respectively) than the bilinear approach (11.8%). Likewise, the comparison of PET images corrected for attenuation using the various methods showed that the proposed method provides better accuracy (6.5%) than the bilinear method (13.4%). Clinical studies further demonstrated that, compared to the bilinear method, the VDECT approach has better agreement for bony structures with the DECT technique (1.5% versus 8.9%) and transmission scanning (8.8% versus 17.7%). CONCLUSIONS: It was concluded that the proposed method outperforms the bilinear method especially in bony structures. Further evaluation using a large clinical PET/CT database is underway to evaluate the potential of the technique in a clinical setting.

Buried penis release in adults with suction lipectomy and abdominoplasty.

The buried penis in adults who had substantial weight gain was treated with a combination of suction lipectomy of the abdomen and pubic area and the release of the suspensory ligament of the penis and with abdominoplasty with suture anchoring of the pubic and penile skin base dermis to the rectus fascia superiorly. This procedure was performed in 11 patients over the past 10 years with satisfactory results. One patient required additional excess skin excision from the side of the pubic and scrotal area to improve the results.

Treatment of alar cartilage malposition using the cartilage disc graft technique.

Patients with a bifid, cephalically rotated, contour-deformed, bulky, overprojected, pinched-tip, alar-dislocated, and/or alar-tethered nose had primary and secondary rhinoplasties using complete lateral alar cartilage mobilization, modification, and repositioning and the cartilage disc tip-graft technique. This technique avoids the pitfalls of classic in situ subtraction rhinoplasty and provides a better way to correct the nasal shape without causing airway obstruction. This technique was performed in 30 patients in the past 6 years who had primary or secondary rhinoplasties, with satisfactory results.

Rejuvenation of the upper arm.

During the course of life, the upper arm demonstrates skin relaxation and fat deposits that become increasingly evident, particularly with age. However, the degree of skin ptosis and accumulation of subcutaneous fat varies from patient to patient. Therefore, it is critical to evaluate each patient individually, to inform the patient of the available options, and to tailor the procedure to his or her needs. We have described four categories of upper-arm problems. Patients with minimal to moderate subcutaneous fat and minimal skin laxity generally do well with circumferential lipectomy alone. With an increased amount of subcutaneous fat and more pronounced skin laxity, suction lipectomy in conjunction with a "ridge" provides good results, with a well hidden scar in the axilla. In the obese patient in whom skin laxity becomes much more noticeable after suction lipectomy, we recommend a purse-string closure of the modest brachioplasty incision to decrease the scar size. In those patients who have minimal fat but extensive skin laxity, a traditional brachioplasty cannot be avoided. Carefully selected and properly informed patients will result in an extremely high satisfaction rate. The techniques and guidelines described are designed to provide simple, easily performed procedures with minimal complications that safely and effectively rejuvenate the upper arm.

The modified cartilage disc tip graft in primary rhinoplasty.

The cartilage disc graft technique with new modifications has been used in primary rhinoplasty during the past 6 years on 51 patients. The technique can be done through closed or open rhinoplasty with other modifications of the tip cartilages or premaxilla. This technique is simple and reliable, and the results are consistently reproducible.

The propeller flap: a one-stage procedure for nipple-areola reconstruction.

The advantages of the propeller flap combined with tattooing for nipple-areola reconstruction include the fact that it is a simple one-stage procedure, a secondary procedure after creation of the nipple-areola complex is eliminated, and a skin graft and the possibility of a skin graft and second wound are eliminated. The propeller flap technique offers the ability to produce a nipple of adequate size, good color match, and satisfactory projection over an 18-month follow-up. The preliminary results of this flap operation are promising. A long-term evaluation of this operation has begun.

The multiplane face lift.

The technique and experience with multiplane face lift are reviewed. The multiplane face lift can be thought of as a fourth-generation rhytidectomy, combining features of the extended SMAS and deep-plane face lifts. It is felt that this lift can more adequately address the problem of the nasolabial fold and can effect better bidirectional pull. Though difficult to quantify, it is expected that this lift will produce a longer-lasting result with no greater risk of complications than the more conventional lift. The multiplane face lift also can be used safely with ancillary procedures, such as blepharoplasty, rhinoplasty, and suction lipectomy.

A national survey of complications associated with suction lipectomy: a comparative study.

In March of 1988, a survey form was sent to all 2695 U.S. and Canadian members of the American Society of Plastic and Reconstructive Surgeons. Nine-hundred and thirty-five members responded, for a response rate of 34.7 percent. The purpose of the survey was to ascertain the total number of major liposuction, dermatolipectomy, and abdominoplasty procedures performed from January of 1984 to January of 1988 and to compare nine specific complications that are associated with these three procedures. The 935 surgeons reported a total of 112,756 procedures performed: major liposuction (75,591), dermatolipectomy (10,603), and abdominoplasty (26,562). Nine major complications were surveyed: mortality, myocardial infarction, cerebrovascular accident or transient ischemic attack, pulmonary thromboembolism, fat embolism, major skin loss, anesthesia complication, transfusion complications, and deep venous thrombosis. The findings in this survey showed, when comparing these three procedures and the nine types of complications, that the complication rate for major suction lipectomy was 0.1 percent, for dermatolipectomy 0.9 percent, and for abdominoplasty 2.0 percent. Fat emboli did not prove to be a significant factor associated with any of the three procedures. However, of the 15 reported deaths (major liposuction 2, dermatolipectomy 2, and abdominoplasty 11), pulmonary thromboembolism was the causative factor in 9 deaths (60 percent). Based on these analyzed data, we feel that major suction lipectomy has a low complication rate and is a reasonably safe procedure.

Contouring of the midtrunk in overweight patients.

Classical abdominoplasty primarily addresses the anterior abdominal wall. It involves a low transverse incision, extensive undermining in the supra-aponeurotic plane, correction of the musculofascial flaccidity, and resection of excessive skin and fat. The introduction of suction lipectomy into the armamentarium of the plastic surgeon has allowed a more thorough, yet safer, contouring of the entire midtrunk. When used in conjunction with a modified W-type abdominoplasty, circumferential suction lipectomy has yielded excellent results in contouring the midtrunk of overweight patients. It is the purpose of this article to present our technique for this procedure.

Suction lipectomy: complications and results by survey.

In October of 1983, we sent a questionnaire on suction lipectomy to 2524 U.S. and Canadian members of the American Society of Plastic and Reconstructive Surgeons. Six-hundred and twelve plastic surgeons returned questionnaires (24.2 percent response rate). One-hundred and seven responding surgeons reported 1573 operations in which suction lipectomy with or without skin excision was used for 2685 procedures on various parts of the body. In the subset of 1249 operations in which suction lipectomy only was used to treat 2261 anatomic areas, surgeons reported greater than 80 percent good or excellent aesthetic results. The overall complication rate was 9.3 percent. The most frequent complications were persistent hypesthesia (2.6 percent), seroma (1.6 percent), and persistent edema (1.4 percent). Skin pigmentation, pain, hematoma, infection, and slough each occurred with an incidence of 1.0 percent or less. Based on the results of this survey, suction lipectomy is a valuable new modality for surgical improvement of body contour.

Reduction suction mammoplasty and suction lipectomy as an adjunct to breast surgery.

Suction lipectomy has become an accepted procedure and its full use is still being elucidated. The author herein describes the use of suction lipectomy as an adjunct in refining the results of established surgical procedures on the breast. The authors also explain the use of suction lipectomy in doing "suction reduction" mammoplasty. The advantages of the use of suction lipectomy as an adjunct to breast surgery and for reduction mammoplasty are explained.