The pseudocapsule in hepatocellular carcinoma: correlation between dynamic MR imaging and pathology.

Nodular hepatocellular carcinoma (HCC) is characterized by the presence of a pseudocapsule (constructed usually from connective fibrous tissue) that appears hypointense on T1- and T2-weighted spin-echo (SE) and gradient-echo (GE) MR imaging sequences without a contrast medium. The presence of vascular structures inside the tumor, which are verified by histological exam, affects enhancement of the PC after administrating the contrast medium: The impregnation is more evident in the dynamic study but also persists on the delayed T1-weighted SE images. The accuracy of MR in detecting the pseudocapsule of HCC and contrast enhancement of the pseudocapsule during dynamic studies were evaluated and related to pathological findings. Thirty-seven HCC were examined in 33 patients and afterwards resected. In capsulated nodules, besides usual hematoxylin, eosin, and trichrome stainings, histochemical and immunohistochemical methods were performed. On a 1.5-T MR unit, T1- and T2-weighted SE and GE FLASH 2D sequences after intravenous injection of Gd-DTPA (dynamic study) were used. In a later phase, T1-weighted SE sequences were repeated. Histologically, the pseudocapsule (thickness 0.2-6 mm) was present in 26 of 37 nodules (70%). The dynamic study was the most suitable technique to show the pseudocapsule, which was recognized in 80.7% (21 of 26 nodules). In 5 of 26 cases, the pseudocapsule, not demonstrated by MR, was thinner than 0.4 mm. In 16 of 21 cases, in the early portal phase (30-60 s), the pseudocapsule had an early enhancement, which was more evident later; in 5 of 21 cases the enhancement was observed only in the late portal phase (1-2 min). At histological examination, 14 of 16 pseudocapsules with early enhancement showed a more prominent vasculature than those with enhancement in the equilibrium phase. Magnetic resonance was a reliable tool in demonstrating the pseudocapsule of HCC. The histological examination demonstrated a good correlation between the enhancement behavior and the vessel number of the pseudocapsule.

[Comparison of ultrasonography and magnetic resonance in the postoperative monitoring of complete subcutaneous rupture of the Achilles tendon]. / Confronto ecotomografia-Risonanza Magnetica nel monitoraggio post-operatorio della rottura sottocutanea completa del tendine d'Achille.

The diagnostic accuracy of US and MRI in the subcutaneous rupture of the Achilles tendon has already been assessed. We used both techniques to study the Achilles tendon during the postoperative repair process after surgery according to Bosworth. The results were compared and discussed in relation to clinical recovery. Ten patients with complete subcutaneous rupture of the Achilles tendon were followed-up with physical examination and submitted to US and MR studies 40, 60 and 90 days postoperatively. Eighty patients recovered in the expected time, while 2 took longer. At 90 days, the US findings in 7 patients and the MR findings in 8 patients who recovered in the expected time could be considered normal. US poorly distinguished the tendon from the reinforcement flap because of gross tendon echostructure. The tendon and the reinforcement flap were not distinguishable at MRI because they were uniformly hypointense. Clinical recovery appeared as a hyperechoic structure and a gross fibrillar pattern at US and as a hypointense structure with some small hyperintense areas at MRI. US and MRI were in disagreement in one patient with a postoperative algodystrophic syndrome, where US showed some alterations which were considered false positives because of clinical recovery and negative MR findings. US and MR patterns were considered abnormal in the 2 patients with delayed recovery. US showed persistent hyperechoic areas within the tendon, while the MR signal was of intermediate intensity in the tendon and reinforcement flap. To conclude, we believe that US is an appropriate technique for the postoperative follow-up of complex subcutaneous ruptures of the Achilles tendon. Additional MRI should be performed in all the cases where US findings are in disagreement with clinics.

[Magnetic resonance angiography with TOF-TONE tridimensional sequences in the study of steno-occlusive diseases of the renal arteries. Comparison with digital angiography]. / Angiografia con Risonanza Magnetica con sequenze tridimensionali TOF-TONE nello studio delle malattie steno-occlusive delle arterie renali. Confronto con angiografia digitale.

The authors examined 32 patients (68 renal arteries in all) with suspected renovascular hypertension with MRA (3D TOF-TONE sequences) and DSA. MRA visualization of the renal vessels was considered good in 96.8%, 91.6%, 76.6% and 16.6% of cases for the ostium, the proximal third, the distal third and the hilum, respectively. MRA correctly assessed the 4 occlusions in our series and 19/20 atherosclerotic stenoses, all in proximal site. In proximal stenosis detection, MRA had 100% sensitivity and 98% specificity in atherosclerotic sclerosis-occlusion grading considering a 50% caliber reduction as the cut-off value. The two techniques were in agreement in 68% of cases; MRA overestimated stenosis grade in 25% of cases. The 3D TOF-TONE sequence is a reliable diagnostic tool in the study of the proximal tract of the renal arteries, but its major limitation remains in distal tract studies. Nevertheless, this technique has elective indications in a selected group of patients, namely the elderly with hypertension and impaired renal function.

[The role of magnetic resonance angiography in the assessment of arterial stenosis in the transplanted kidney]. / Ruolo dell'angiografia con Risonanza Magnetica nella valutazione delle stenosi dell'arteria del rene trapiantato.

Artery stenosis in the transplanted kidney is the most frequent vascular complication; hypertension onset or worsening may be associated and, at an end stage, also renal insufficiency. The diagnosis must be early and accurate and provide guidelines for medical, interventional or surgical therapy. To assess the diagnostic reliability or MRA, 27 patients were examined. On the basis of clinical, biochemical, pharmacological (Captopril test) and instrumental (color-Doppler US) examinations, the artery of the transplanted kidney was considered normal in 6 patients and stenotic in 21. In the control group, MRA results were in agreement with color-Doppler findings. On the contrary, in 8 of 21 abnormal conditions, the two techniques were in disagreement. Digital angiography, considered as the gold standard, was performed in any questionable case, confirming a slight overestimation of the stenoses by MRA (3 cases) and 2 false positives by color-Doppler US. The authors believe color-Doppler US to be a reliable technique for screening stenosed arteries in the transplanted kidney. MRA is proposed as a complementary investigation useful to define stenosis type and to provide guidelines for treatment.