Despite disappearance on Eovist MR imaging (the most sensitive available imaging modality), 38.5% of all colorectal metastases disappeared and of those, 55% were viable.
The general contribution of the cerebellum to hypoxic respiratory responses and the special role of the fastigial nucleus (FN) in the hypoxic respiratory reflex mediated via peripheral chemoreceptors were investigated in anesthetized and spontaneously breathing cats. Seven cats were exposed to isocapnic progressive hypoxia before and after cerebellectomy by decreasing the fractional concentration of end-tidal O2 (FETO2) from 15 +/- 0.3% to 7% while maintaining the pressure of end-tidal CO2 at a constant level of approximately 30 mmHg. Five additional cats inhaled five breaths of pure N2 (transient hypoxia) and received sodium cyanide (50 micrograms iv) before and after thermal lesions of the bilateral FN. The results showed that cerebellectomy or FN lesions failed to alter the respiratory variables (minute ventilation, tidal volume, respiratory frequency, and the peak of integrated diaphragm activity) during eupneic breathing. However, cerebellectomy significantly attenuated minute ventilation (FETO2 < or = 13%) and the peak of integrated diaphragm activity (FETO2 < or = 10%) compared with control. During progressive hypoxia, changes in respiratory frequency were noted earlier (FETO2 < or = 13%) than changes in tidal volume (FETO2 < or = 10%). Similarly, bilateral lesions of the FN resulted in a profound reduction in these respiratory responses to transient hypoxia and sodium cyanide. We conclude that the cerebellum can facilitate the respiratory response to hypoxia and that the FN is an important region in the modulation of the hypoxic respiratory responses, presumably via its effects on inputs from peripheral chemoreceptors.
Purpose: To demonstrate the feasibility of detecting patency, stenosis, or occlusion of transjugular intrahepatic portosystemic shunts (TIPS) with 4D Flow MR. Materials and Methods: Sequential adult patients with TIPS were eligible for enrollment. A volumetric phase contrast sequence was used to image the TIPS. Particle tracing CINE images were used for qualitative assessment of stenosis. TIPS were segmented to generate quantitative data sets of peak velocity. Segmentation and quantitative measurement of flow throughout an entire TIPS stent defined technical success. Comparison was made to Doppler US. Venogram, when available, and 6-month clinical follow-up were used as reference standards. Results: 4D Flow MR was performed in 23 patient encounters, and was technically successful in 16/23 encounters. Three cases demonstrated both focal turbulence and abnormal velocities (>190cm/s or <90cm/s) on 4D Flow and had venogram confirmed stenosis (true positives). Seven cases had normal velocities and no turbulence on 4D Flow and all were confirmed negative with clinical follow-up or venogram (true negatives). Six cases had discordant 4D flow results, with abnormal velocities but no turbulence, or focal turbulence but normal velocities. All six discordant cases had no evidence of dysfunction with 6-month follow-up. Conclusion: 4D Flow MR can detect TIPS patency and stenosis, but requires further investigation before it can be used to assess for TIPS dysfunction.
The final impression by the two retrospectively reviewing radiologists of MR examinations performed for suspected appendicitis during pregnancy had near-perfect agreement. In patients where the appendix could not be visualized or in patients that were interpreted as indeterminate, no patients had acute appendicitis. Advances in knowledge: MR impression for suspected appendicitis in the pregnant patient has high interradiologist agreement, and a non-visualized appendix or lack of inflammatory findings at the time of MR, reliably excludes surgical appendicitis.
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