ABSTRACT
AIM: Strain elastography is a method for recording tissue hardness. Strain in different areas may be compared using strain ratio (SR). The aims of this study were to validate a previously proposed SR cut-off value of 1.25 for differentiating adenocarcinomas from adenomas and to compare the performance of endorectal ultrasonography (ERUS), strain elastography and MRI in the same patients. METHOD: A prospective evaluation of 120 consecutive patients with rectal neoplasia, using a predetermined elastography strain ratio cut-off value, was performed to differentiate adenomas from adenocarcinomas. ERUS and MRI were performed according to standard routine at Haukeland University Hospital, defining T0 as adenomas and T1-T4 as adenocarcinomas. Subsequent histopathology was used as the reference standard. RESULTS: Histopathological evaluation revealed 21 adenomas and 99 adenocarcinomas. Sensitivity, specificity and accuracy (with 95% CI) were as follows: ERUS: 0.96 (0.90-0.99), 0.62 (0.40-0.80) and 0.90 (0.83-0.94); elastography SR: 0.96 (0.90-0.99), 0.86 (0.66-0.96) and 0.94 (0.88-0.97); and MRI: 0.99 (0.94-1.00), 0.07 (0.00-0.31) and 0.87 (0.80-0.93). CONCLUSION: This study confirms that the elastography SR assessment accurately differentiates sessile adenomas from adenocarcinomas. SR assessment has a superior ability to differentiate adenomas and adenocarcinomas when compared with ERUS and MRI. MRI examination seems unable to recognize adenomas and should be interpreted with care when early-stage rectal neoplasia is suspected.
Subject(s)
Adenocarcinoma/diagnosis , Adenoma/diagnosis , Elasticity Imaging Techniques/statistics & numerical data , Endosonography/statistics & numerical data , Magnetic Resonance Imaging/statistics & numerical data , Rectal Neoplasms/diagnosis , Adenocarcinoma/pathology , Adenoma/pathology , Adult , Aged , Aged, 80 and over , Diagnosis, Differential , Elasticity Imaging Techniques/methods , Endosonography/methods , Female , Humans , Magnetic Resonance Imaging/methods , Male , Middle Aged , Prospective Studies , Rectal Neoplasms/pathology , Rectum/diagnostic imaging , Sensitivity and SpecificityABSTRACT
OBJECTIVE: In the recent past it has become clear that the kallikrein-kinin system is closely intertwined with long-term blood pressure regulation. It was shown that a kinin B2 receptor blockade leads to a sodium-dependent rise in blood pressure. The underlying mechanisms of this phenomenon, however, remain unclear. The osmotic gradient of the renal medulla is a prerequisite for the preservation of volume and sodium by the kidney. We thus hypothesized, that a kinin dependent modulation of medullary blood flow accounts for the influence of sodium on blood pressure. METHODS: In 39 urethane anaesthetized rats pressure dependent regulation of whole kidney blood flow and cortical and medullary blood flow were estimated via laser-Doppler flux by a stepwise reduction of renal perfusion pressure to 30 mm Hg. RESULTS: In controls (n = 15), a reduction in renal perfusion pressure to 30 mm Hg lead to a concomitant reduction in whole kidney blood flow (25 +/- 3% of baseline) and cortical laser-Doppler flux (36 +/- 5% of baseline). In contrast, medullary laser-Doppler flux decreased only to 79 +/- 8% of the baseline level. Providing a 2% sodium chloride solution as drinking water over 5 days (n = 12), resulted in a significantly lower capability to autoregulate medullary flow (50 +/- 6% of baseline, P < 0.05). Acute subcutaneous administration of Hoe 140, a bradykinin B2 receptor antagonist (300 micrograms/kg bwt), restored autoregulation of medullary flow to almost normal levels (93 +/- 12% of baseline, P < 0.01 versus high sodium diet alone, n = 12). CONCLUSIONS: Our results indicate that B2 receptor blockade restores the attenuated autoregulation of medullary Doppler flux during sodium enriched diet. This, suggests that the kinin dependent impact of sodium on blood pressure regulation is mediated by modulations of medullary blood flow autoregulation.