44 research outputs found
Rilevamento dei centri di istantanea rotazione del rachide lombare.Applicazione clinica.
Rx ed identificazione dell’agente balistico: attualità , problemi medico-legali e proposta di metodica valutativa
Non cardiopatic and cardiopatic beta thalassemic patients: quantitative and qualitative cardiac iron deposition evaluation with MRI
Poly-L-lactic acid - hydroxyapatite (PLLA-HA) bioabsorbable interference screws for tibial graft fixation in anterior cruciate ligament (ACL) reconstruction surgery: MR evaluation of osteointegration and degradation features.
Abstract
Purpose. We evaluated with magnetic resonance imaging
(MRI) the degradation and osteointegration features of a
new type of bioabsorbable interference (BioRCI) screw
composed of poly-L-lactic acid and hydroxyapatite
(PLLA-HA) used for tibial graft fixation in anterior
cruciate ligament (ACL) reconstruction.
Materials and methods. Thirty-one patients underwent
arthroscopic surgery for ACL reconstruction using doubled
gracilis and semitendinosus tendons fixed to the tibial
tunnel with PLLA-HA (BioRCI-HA) screws. Two groups
of patients were evaluated, one group 10–13 months after
surgery and the other after 30–40 months. The standard
knee ligament evaluation form of the International Knee
Documentation Committee (IKDC) was used for clinical
assessment and MRI for the radiological assessment.
Results. MRI after 10–13 months revealed findings
referable to healing and integration of the
bone–graft–screw system, findings that disappeared at later
follow-up examinations. The BioRCI-HA screw remained
constantly visible in all patients, although with changes in
signal intensity over time.
Conclusions. BioRCI-HA screws allow adequate primary
stability and superior osteoconduction and biocompatibility
in comparison with plain PLLA screws. The absence of
ferromagnetic artefacts allows accurate MRI follow-up and adequate evaluation of ligament synovialisation, screw
degradation and graft osteointegration.
Keywords Bioabsorbable interference screws ·
Hydroxyapatite · Osteointegration · Magnetic resonanc
Doppio contrasto in RM epatica ( RM-DC): uso sequenziale-combinato di MDC negativi e positivi.
Valutazione RM dei noduli displasici e degli epatocarcinomi nel fegato cirrotico: ruolo dei mezzi di contrasto superparamagnetici.
Double-contrast MRI (DC-MRI) in the study of the cirrhotic liver: utility of administering Gd-DTPA as a complement to examinations in which SPIO liver uptake and distribution alterations (SPIO-LUDA) are present and in the identification and characterisation of focal lesions.
Purpose. The aim of this study was to compare the performance of
double-contrast magnetic resonance imaging (DC-MRI) with the
sequential use of superparamagnetic iron oxide (SPIO) and
gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA)
contrast agents compared with unenhanced MRI and SPIOenhanced
MRI (SPIO-MRI) in the study of the cirrhotic liver.
Special attention was paid to cases in which alterations of liver
uptake and distribution of the SPIO contrast medium [SPIO-liver
uptake and distribution alterations (SPIO-LUDA)] could lead to
diagnostic errors at SPIO-MRI.
Materials and methods. We used DC-MRI to study 67 patients
suffering from hepatic cirrhosis and on a waiting list for liver
transplant. The study was performed with a 1.5-Tesla device and
characterised by three phases: the first phase without contrast
material (unenhanced MRI), the second after the administration of
ferumoxides (SPIO-MRI), and the third, a double-contrast study
following the injection of a bolus of paramagnetic contrast
material (DC-MRI). The sensitivity of unenhanced MRI, SPIOMRI
and DC-MRI in identifying and characterising hepatic focal
lesions was assessed, together with the diagnostic increment of
one technique with respect to the others. The gold standard was
histological confirmation in 38 cases and clinical–radiological
follow-up in all cases. Liver function, kidney function, blood tests
and urinalysis were performed in all patients 24–48 h before and
after the MRI examination.
Results. In 14/67 cases (20.8%), SPIO-LUDA were present, which
posed a limitation to the SPIO-MRI examination. Focal lesions
were absent in 44 patients, and the action of the ferumoxides was
reduced by the presence of SPIO-LUDA in nine cases. There were
five cases of confluent fibrosis, two of decompensated cirrhosis,
one of vascular thrombosis, and one of scarring in a patient who had undergone hepatic resection for hepatocellular carcinoma
(HCC). In all these cases, completion of the MR examination with
the DC technique clarified the MR picture, confirming the absence
of focal lesions. Twenty-three patients had a total of 68 lesions,
which consisted of 37 dysplastic nodules (DN), 19 HCC nodules,
two relapses of HCC following chemoembolisation, two HCC
associated with portal thrombosis, one cancer-cirrhosis, two
angiomas and five small cysts. SPIO-LUDA were present in five
patients, thus limiting the identification, characterisation or
assessment of the real size of the lesions. SPIO-LUDA were the
result of vascular thrombosis in one case and fibrosis in four cases.
In all of these cases, DC-MRI proved useful for diagnosis. The
sensitivity of unenhanced MRI, SPIO-MRI and DC-MRI for
lesion detection was 57.3%, 67.6% and 75%, respectively. The
results obtained in the characterisation of the lesions were 20.5%,
63.2% and 73.5% for unenhanced MRI, SPIO-MRI and DC-MRI,
respectively. The diagnostic increment of SPIO-MRI over
unenhanced MRI for lesion identification and characterisation was
9% and 42.7%, respectively, whereas the diagnostic increment of
DC-MRI over SPIO-MRI was 7.4% and 10.3%, respectively.
Conclusions. In our study, the combined use of two contrast
agents, negative and positive, provided greater diagnostic
confidence and caused no side effects in the patients.
Key words MR • Liver • Cirrhosis • Contrast • Mediu