Dorsal scapular artery as a recipient vessel in the vessel-depleted neck during free tissue transfer in head and neck reconstruction.

BACKGROUND: The vessel-depleted neck poses a unique challenge to the microvascular surgeon. Using 3D modeling and cadaveric dissection, we describe the approach and advantages of a known but less frequently used recipient vessel, the dorsal scapular artery, during free tissue transfer. METHODS: Three patients with vessel-depleted necks required reconstruction with free tissue transfer. The dorsal scapular artery was used as a recipient vessel. Three-dimensional anatomic models were created and cadaveric dissections were performed to characterize the anatomy. RESULTS: The dorsal scapular artery was successfully used in 3 patients as the recipient pedicle for free tissue transfer. The vessel was identified deep in the posterior triangle after emerging through the brachial plexus. In all cases, the artery was in a previously undissected field, and had a large caliber and favorable geometry for microvascular anastomosis. CONCLUSION: The dorsal scapular artery is a viable recipient vessel during head and neck reconstruction in the vessel-depleted neck.

Renal remodeling after abdominal radiation therapy: parenchymal and functional changes.

OBJECTIVE: The purpose of this study was to quantify changes in renal length, volume, and function over time after upper abdominal radiation therapy. MATERIALS AND METHODS: Imaging and clinical data were retrospectively reviewed for 27 adults with abdominal radiation therapy between 2001 and 2012. All had two kidneys, radiation exposure to one kidney, and survival of at least 1 year after therapy. Mean prescribed dose was 52 ± 9 Gy to extrarenal targets. Length and volume of exposed and unexposed kidneys were measured on CT scans before treatment (baseline) and at intervals 0-3, 3-6, 6-12, 12-24, 24-36, and more than 36 months after completion of radiotherapy. Serum creatinine was correlated at each interval. Mixed-models ANOVA was used to test renal length and volume, serum creatinine, and time against multiple models to assess for temporal effects; specific time intervals were compared in pairwise manner. RESULTS: Mean follow-up duration was 35 months (range, 5-94 months). Exposed kidney length and volume progressively decreased from baseline throughout follow-up, with mean loss of 23% (p < 0.001) and 47% (p < 0.001), respectively. Slight increase in unexposed kidney length was not significant. Mean serum creatinine increased from 0.86 ± 0.18 mg/dL at baseline to 1.12 ± 0.27 mg/dL at 12-24 months (p < 0.001), then stabilized. CONCLUSION: Kidneys exposed to radiation during therapy of adjacent malignancies exhibited continuous progressive atrophy for the entire follow-up period, nearly 8 years. Volume changes were twice as great as length changes. Renal function also declined. To accurately interpret follow-up studies in cancer survivors, radiologists should be aware of the potential for progressive renal atrophy, even many years after radiation therapy.

Sources of error in the measurement of aortic diameter in computed tomography scans.

OBJECTIVE: This study was conducted to determine the differences in the diameter of the thoracic aorta when measured from electrocardiographic (ECG)-gated and nongated computed tomography (CT) angiography. Another aim was to define the difference in the aortic diameter when it is measured at peak systole and end diastole in ECG-gated scans. METHODS: The gated and nongated CT angiograms of 27 patients (mean age, 58 ± 16 standard deviation [SD] years) obtained on a 256-slice multidetector CT scanner were used. The transverse and anteroposterior diameters and the lumen areas were measured at 1, 4, and 8 cm below the origin of the left subclavian artery. RESULTS: There was a significant difference in the aortic measurements of diameter between gated and nongated scans found in samples taken at 1, 4, and 8 cm distal to the left subclavian artery (P < .0001). We found a considerable difference between the systolic and diastolic diameters (P < .0001). The maximum change in diameter between systole and diastole was 2.9 ± 0.9 (SD) mm (14.5%, P < .0001) at 1 cm, 5.4 mm (22.6%; median, 1.7 mm; P < .0001) at 4 cm, and 4.4 mm (16.9%; median, 1.3 mm; P < .0001) at 8 cm. There was a significant difference between the transverse and anteroposterior diameters in systole and diastole at all locations (P < .0001): The maximum change in diameter between transverse and anteroposterior diameters in systole was 5.4 ± 1.1 (SD) mm (15.7%, P < .0001) at 1 cm, 5.8 mm (19%; median, 1.4 mm; P < .0001) at 4 cm, and 5 mm (15%; median, 1.02 mm; P < .0001) at 8 cm. There was also a substantial difference between measuring the transverse diameter directly and deriving it from the lumen area (P < .0001). CONCLUSIONS: Our results showed an important difference between systolic and diastolic diameters measurements in ECG-gated scans. The standard protocol for measuring aortic diameters in gated scans of the thoracic aorta uses images at end diastole because the lack of wall motion at this time provides better resolution. This is likely to result in undersizing that, in some instances, may threaten stability and the proper seal of the stent graft. The dimensions of the aorta in a gated CT should be measured at peak systole rather than the conventional end diastole used today. Most medical centers use nongated CT or gated CT scans in end diastole to calculate sizes of endografts. In view of our findings, the latter method could result in potential complications.

Evaluation of mechanical heart valve size and function with ECG-gated 64-MDCT.

OBJECTIVE: The purpose of our study was to determine whether CT can accurately evaluate mechanical heart valve size and function. MATERIALS AND METHODS: Sixty-two patients with mechanical valves (37 single-disc, 27 bileaflet; 59 aortic, 5 mitral) were evaluated with ECG-gated 64-MDCT and transthoracic echocardiography; a subset of 10 patients underwent cinefluoroscopy. Two readers independently interpreted each study. RESULTS: The mean age of the patients was 46.4 +/- 14.4 years; 50 were men and 12 were women. There was excellent correlation, and differences between CT readers were absent to small in measuring the opening angle (r = 0.96, p < 0.001; 76.7 +/- 9.0 degrees vs 76.8 +/- 9.6 degrees , p = 0.73), annulus diameter (r = 0.96, p < 0.001; 25.9 +/- 3.3 vs 25.9 +/- 3.2 mm, p = 0.62), and geometric orifice area (r = 0.98, p < 0.001; 3.8 +/- 0.9 vs 3.6 +/- 0.8 cm(2), p < 0.001). There was strong correlation without difference in opening angle between CT and cinefluoroscopy (r = 0.77, p < 0.001; 79.2 degrees +/- 9.8 degrees vs 77.2 degrees +/- 15.5 degrees , p = 0.45). Compared with manufacturer specifications, CT reported opening angles that were smaller for single-disc valves (n = 36, 67.4 degrees +/- 5.7 degrees vs 75 degrees , p < 0.001) and similar for bileaflet valves (n = 42 for 21 valves, 83.8 degrees +/- 3.9 degrees vs 85 degrees , p = 0.05), valves, with small underestimation with CT versus specifications in annulus diameter (n = 41; r = 0.75, p < 0.001; 26.4 +/- 3.0 vs 27.5 +/- 3.3 mm, p = 0.003), and geometric orifice area (n = 35; r = 0.90, p < 0.001; 3.7 +/- 0.7 vs 3.8 +/- 0.8 cm(2), p = 0.04). Each disc closed fully on CT; none had more than mild regurgitation on echocardiography. CONCLUSION: CT can measure the size and function of mechanical valves with high interobserver agreement and results similar to specifications. The opening angle with CT strongly correlates with cinefluoroscopy. CT is promising for the assessment of mechanical valves.

Hemodynamic and functional assessment of mechanical aortic valves using combined echocardiography and multidetector computed tomography.

BACKGROUND: Limitations are found in the ability of transthoracic echocardiography to evaluate mechanical aortic valve replacements (AVR). We evaluated the ability of combined echocardiography and computed tomography (CT) to enhance the hemodynamic and functional evaluation of AVR. METHODS: We performed a retrospective evaluation of 41 consecutive patients with AVR (27 bileaflet, 14 single disc) and both transthoracic echocardiography and 64-detector electrocardiographic-gated CT. Each study was interpreted by 2 independent, blinded readers. The effective orifice area was compared with the corrected energy-loss coefficient area and the geometric orifice area. Patients with an elevated mean pressure gradient (>15 mm Hg) were assessed for potential abnormal findings, including patient-prosthesis mismatch, elevated cardiac index, valve dysfunction, significant regurgitation, or pressure recovery effect. RESULTS: Significant differences (P<0.05) and moderate-to-high correlations (r=0.55-0.98) were observed between the effective orifice area (2.2+/-0.8 cm(2)), corrected energy-loss coefficient area (3.0+/-1.5 cm(2)), and geometric orifice area (3.6+/-0.9 cm(2)). At least one abnormality was observed in 7 of 25 patients with normal gradients and in 14 of 16 patients with elevated gradients (P<0.001). In 16 patients with elevated mean pressure gradient, a potential cause could be determined in 4 with echocardiography alone and in 14 patients with combined echocardiography and CT (P=0.001). CONCLUSION: CT aids in the interrogation of prosthetic valve function, enhancing evaluation for patient prosthesis mismatch, and correction for pressure recovery by the corrected energy-loss coefficient. CT is additive to the assessment of mechanical AVR with transthoracic echocardiography, and the combination permits a more complete assessment of both AVR function and hemodynamics.

Thyroid carcinoma metastasis to skull with infringement of brain: treatment with radioiodine.

BACKGROUND: Infringement by differentiated thyroid carcinoma on the brain is rare but, when suspected, the patient deserves special attention. A patient with an enlarging metastasis of thyroid carcinoma to the skull that was impinging on the brain illustrates diagnostic and therapeutic strategies applicable to the treatment of metastatic carcinoma. METHODS: A case study was performed. Computed tomography (CT) and magnetic resonance imaging (MRI) were done, serum thyroglobulin was measured, and tumor responses to thyroxine and (131)I treatments were monitored. Tumor dosimetry, enabled by scintigraphy with (131)I employing single photon emission tomography fused with CT (SPECT-CT), was performed. RESULTS: The metastasis was from a follicular variant of papillary thyroid carcinoma. During thyrotropin stimulation the tumor enlarged. The tumor decreased in volume after each of two (131)I therapies. Dosimetry indicated delivery of 1970 and 2870 cGy to the tumor and 35 and 42 cGy to the brain, respectively, in the two treatments. The patient has survived for more than 11 years since diagnosis. CONCLUSIONS: A metastasis from a follicular variant of papillary carcinoma increased in volume during hypothyroidism producing more infringement on the brain. Beyond the effects of thyroxine therapy, (131)I treatments induced recession of tumor volume. In patients with metastases that concentrate (131)I, dosimetry with SPECT-CT can predict absorbed doses of radiation to the tumor and to the adjacent organs and thus lay a basis for data-based decisions on (131)I therapies. Therapy may induce prolonged survival in patients with metastases infringing on the brain.