The imaging of regional ventilation in the lungs is essential for the evaluation of a variety of pathological conditions, such as emphysema, pneumonia and pulmonary embolism. We propose a novel approach for ventilation scanning, using magnetic resonance imaging (MRI) and inhaled molecular oxygen as a contrast agent, that directly depicts transfer of oxygen across the alveolus into the pulmonary vasculature. Molecular oxygen is only weakly paramagnetic but produces substantial signal changes in the lungs because of their large surface area. Ventilation defects were shown in a patient with bullous emphysema, and ventilation-perfusion mismatches were shown in two patients with pulmonary embolism.

The effect of the oxygen inhalation on relaxation times was evaluated in various tissues, including the myocardium, liver, spleen, skeletal muscle, subcutaneous fat, bone marrow, and arterial blood, with a [1H]MR system. Statistically significant decrease of T1 relaxation times was observed in the myocardium, spleen, and arterial blood after inhalation of 100% oxygen, whereas no significant change was observed in liver, skeletal muscle, subcutaneous fat, or bone marrow. The T2 relaxation time of these tissues did not differ significantly between before and after inhalation of the oxygen. These results indicate that [1H]MRI can be used to evaluate changes with oxygen inhalation and that the effect of the oxygen inhalation on T1 relaxation time is different among various tissues.

Various LV functional parameters were measured with multi-detector row CT with a segmental approach, and measurements correlated and agreed with those obtained with MR imaging. Moreover, functional analysis with multi-detector row CT was more accurate than that with two-dimensional echocardiography or ECG-gated SPECT.

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Enhanced external counterpulsation therapy improved myocardial perfusion at rest and with dipyridamole and was associated with an increased exercise tolerance with(13)N-ammonia positron emission tomography and increased nitric oxide levels. These results suggest that one of the enhanced external counterpulsation mechanisms is development and recruitment of collateral vessels.

Delayed enhanced MRI is considered a useful method for the early identification of cardiac sarcoidosis. Delayed hyperenhancement is frequently associated with a reduction of regional wall motion and thallium-201 perfusion defects.

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Reinjection- and MIBI-g-SPECT provide clinically satisfactory various functional data. These functional data in combination with the perfusion information will improve diagnostic and prognostic accuracy without an increase in cost or the radiation dose to the patients.