[Radiological assessment of interstitial lung disease: what can lung ultrasound do?]

The use of lung ultrasound in the screening, diagnosis, and evaluation of interstitial lung disease has been relatively well studied, but has not been widely accepted and applied in clinical practice. There are also some differences in the examination methods applied in these studies. This paper summarized the application, advantages, and disadvantages of lung ultrasound in the diagnosis and follow-up of interstitial lung disease by comprehensively reviewing the examination methods, research results and progress of new technologies of lung ultrasound in interstitial lung disease.

Heterotopic heart transplantation in rats: improved anesthetic and surgical technique.

OBJECTIVE: An updated anesthetic and surgical technique in a rat model of heterotopic heart transplantation is described. MATERIALS AND METHODS: A microsurgical technique via a suprarenal approach was performed, and is described in stepwise fashion, and several technical improvements are compared with previous descriptions. Lewis rats were used as donors and recipients (syngeneic model). RESULTS: Factors that affected early surgical outcome included type of anesthetic used; surgeon skill, experience in handling blood vessels, and knowledge of small-animal anatomy; gentle manipulation during the operation; and duration of surgery (<1 hour). Use of isoflurane inhalation anesthesia (10 rats) vs intraperitoneal injection of ketamine, 75 mg/kg, and dexmedetomidine, 0.25 mg/kg (20 rats), was associated with improved early survival (90%) and no occurrence of paralysis, paraparesis, bleeding, or intestinal ischemia. Long-term survival (>11 months) with a functioning graft was achieved in all 9 surviving animals. CONCLUSIONS: Survival was substantially improved with administration of isoflurane anesthesia; surgeon microvascular surgical skills and knowledge of small-animal anatomy, and duration of surgery less than 1 hour. These factors collectively contributed to successful early outcomes after heterotopic heart transplantation in rats, with 90% freedom from morbidity and mortality, and resulted in long-term survival (>11 months) with a functioning graft in a syngeneic model. This heterotopic model in rats is suitable for short- and long-term studies of heart transplantation.

Evaluation of Motexafin gadolinium (MGd) as a contrast agent for intraoperative MRI.

OBJECTIVE: The characteristics of an ideal contrast agent for use in the intraoperative MRI would be tumor-specificity and intracellular localization, combined with extended tumor enhancement, but with rapid elimination from the blood. The radiation sensitizing properties of Motexafin gadolinium (MGd) have been investigated in a number of clinical trials involving patients with brain metastases. These studies clearly show that MGd is detectable in magnetic resonance images many days following administration. The aim of this experimental study was to test whether Motexafin gadolinium (MGd) could serve as an efficient intraoperative contrast agent avoiding problems that arise with surgically induced intracranial enhancement. METHODS: F98 orthotopic brain tumors or surgical lesions were induced in Fisher rats. T1-weighted MRI studies were performed with either a single or multiple daily doses of MGd. The last contrast dose was administered either 7 or 24 hours prior to scanning in both tumor-bearing or surgically-treated animals. All scans were T1-weighted nce (TR=495 ms; TE=1 ms.) with a slice thickness of 1.0 mm. Three tubes containing 2.3, 0.23 and 0.023 mg/mL of MGd (in physiological saline) respectively, were used as standards to calibrate the scans. RESULTS: Animals receiving either 30 or 60 mg/kg MGd i.v. developed clinical signs of impaired motor activity, and increasing lethargy and were euthanized 48 hours after MGd administration due to their poor and deteriorating condition. MGd given i.p. was tolerated up to a dose of 140 mg/kg. Despite multiple dosages and several administration modes (i.p., i.v.) no significant enhancement was observed if the scans were performed 7 or 24 hours following the last MGd dose. Clear enhancement was seen though when the scans were performed 30 min following MGd administration, indicating that the agent was being taken up by the tumor. Scans of necrotic lesions though were positive though 7 hours following MGd injection. MGd scans had no significant enhancement following surgically-induced lesions while scans with conventional contrast agents showed both meningeal and intraparenchymal enhancement. CONCLUSION: This study suggests that MGd is not sequestered in viable tumor for the necessary time interval required to allow delayed imaging in this model. The agent does seem to remain in necrotic tissue for longer time intervals. MGd therefore would not be suitable as a contrast agent in intraoperative MRI for the detection of remaining tumor tissue during surgery.

Comparative Ngas measurements for a parallel plate chamber in proton, electron, and 60Co beams.

The TG21 protocol introduced the Ngas calibration method for parallel plate chambers in high-energy electron beams. This calibration method was performed for a Markus parallel plate chamber in proton and electron beams of various energies as well as a 60Co beam. For an individual chamber, the Ngas value in proton beams differs from the Ngas value in cobalt and electron beams by the ratio of (W/e) for proton beams to that of a 60Co beam. While the replacement correction factor is essential for Markus chambers in low-energy electron beams, the results of our Nppgas measurements in proton beams showed that the Markus chamber does not need a replacement correction factor for therapeutic proton beams of energy 20-170 MeV. These results indicate that the 0.7-mm guard ring of the Markus chamber is adequate to prevent the in-scattering of secondary electrons produced by proton irradiation of the chamber wall or medium.