High-power, high repetition-rate, green-pumped, picosecond LBO optical parametric oscillator.

We report on a picosecond, green-pumped, lithium triborate optical parametric oscillator with record-high output power. It was synchronously pumped by a frequency-doubled (530 nm), pulse-compressed (4.4 ps), high-repetition-rate (230 MHz), fiber-amplified gain-switched laser diode. For a pump power of 17 W, a maximum signal and idler power of 3.7 W and 1.8 W was obtained from the optical parametric oscillator. A signal pulse duration of ~3.2 ps was measured and wide tunability from 651 nm to 1040 nm for the signal and from 1081 nm to 2851 nm for the idler was achieved.

High energy femtosecond fiber chirped pulse amplification system with adaptive phase control.

We demonstrate increased peak power from an Yb fiber CPA system operating with strong self-phase modulation by shaping the spectral-phase of the input pulses. An adaptive control loop used feedback from the output autocorrelation. We investigated pre-compensation of both SPM phase distortion at high energies, and residual dispersion from mismatched stretcher/compressor technologies at low energies. Phase shaping resulted in improved pulse quality. When using a bulk grating stretcher, shaping increased the autocorrelation peak by a factor of 2.9, and with a fiber stretcher, shaping increased the autocorrelation peak by a factor of 3.4. High-quality 800 fs, 65 microJ recompressed pulses were produced. This technique could benefit a wide variety of fiber amplifier systems and is self-optimising for operation at both low and high pulse energies.

Scapular free flap for repair of massive lower facial composite defects.

The scapular osteocutaneous free flap provides excellent tissue for reconstruction of massive lower facial defects. Five cases of full-thickness cheek and lip defects associated with mandibular loss were successfully repaired with sandwiched osteocutaneous scapular flaps plus a parascapular or latissimus dorsi flap. In two instances the osteocutaneous scapular flap was harvested along with a parascapular skin paddle. The other three patients had latissimus dorsi myocutaneous units taken with the scapular osteocutaneous flap from the same subscapular pedicle.

Accuracy of frozen-section diagnosis in salivary gland lesions.

A retrospective study is presented comparing the results of 462 frozen-section analyses of surgically extirpated salivary gland tumors with the permanent-section results. The overall agreement between frozen- and permanent-section analyses was 95.7%. A separate review of the last 47 months of this 32-year study revealed an accuracy rate of 98.8%. Frozen-section diagnosis of salivary gland tumors has been reliable and clinically valuable in our practice.

Lymphoma presenting as a salivary gland mass.

A retrospective review of 36 cases of lymphoma presenting as a salivary gland mass was conducted over a 34-year period. A significant increase in the occurrence of lymphoma was noted in proportion to other salivary gland tumors (P less than 0.01, chi 2 analysis: 1954-1972, 11 of 714 (1.5%); 1973-1979, 9 of 201 (4.5%); 1980-1987, 16 of 265 (6.0%). The mean age was 61 years, sex distribution was equal, and 75% occurred in the parotid. Only 42% presented with signs or symptoms other than a painless mass. Glandular excision was done in early stages of the disease while biopsy was done at later stages. Frozen section analysis was accurate in all but one case and was useful in determining if biopsy were adequate. All patients were definitively treated with chemotherapy and/or radiotherapy. Several instructive points are apparent. Any patient presenting with an isolated salivary gland mass can have a lymphoma. There has, in fact, been a significantly increasing proportion of salivary gland lymphoma among the various salivary gland tumors in our patient population. In contrast to other salivary gland tumors, surgery is reserved for diagnosis and not for treatment. A lymph node biopsy may be sufficient to establish a diagnosis, in which case, glandular excision is unnecessary. Most of the patients presented with an asymptomatic isolated salivary gland mass. The presence of adjacent adenopathy, a rubbery feel to the mass, and the intraoperative appearance were the most suggestive signs of lymphoma. Frozen section analysis is helpful in determining the appropriate extent of surgery and is recommended.

The pseudocapsule of pleomorphic adenomas (benign mixed tumors): the argument against enucleation.

The "well encapsulated" pleomorphic adenoma has at best a pseudocapsule which allows for bits of satellite tumor to be left behind at ""enucleation" surgery as well as for easy "spillage" of tumor by the overconfident surgeon. Recurrent pleomorphic adenomas then become difficult tumors to eradicate and place vital structures, such as the facial nerve, in jeopardy.

Management of recurrent salivary gland tumors.

The management of 129 patients with recurrent tumors of the salivary glands is analyzed, Principles of approaching recurrent tumors and guidelines for their management are outlined in detail. Age distribution, symptoms, time to recurrence, cases that showed possible malignant degeneration, and complications are reviewed. The surgical procedures, recurrence rate, and survival rates are recorded.

Submandibular gland tumors.

Tumors involving the submandibular gland are rare. However, the incidence of malignancy is much higher than in the parotid (approaching 50 percent). In addition, the 5-year survival rate in patients with malignant tumors of the submandibular gland is much poorer in our series--28 percent versus 71.8 percent for the parotid gland. Because of the poor prognosis in patients with malignant tumors involving the submandibular gland we feel that composite resections should be carried out for all tumors except low-grade mucoepidermoid tumors. In addition, postoperative radiation should be given for specific indications (detailed in the article).

Pitfalls of comparative photography in plastic and reconstructive surgery.

Some of the pitfalls of comparative scientific photography are reviewed. Methods of avoiding these pitfalls and for maintaining consistency are suggested.