Metastatic disease of the spine.

Metastases of the spine occur in the spinal cord, dura extramedullary, epidural space, and vertebral bodies. Imaging modalities can be used to evaluate patient symptoms, screen and detect lesions, assess localization and the compartments involved (extradural, epidural, subdural, and paraspinal), and suggest therapeutic strategies. The suggested flow chart for metastases is (1) in asymptomatic patients suspected for metastases and (2) in the patient with neurological symptoms. Imaging modalities are indispensable in differential diagnosis because some nontumoral lesions can mimic metastases.

Evaluation of patellar chondromalacia with MR: comparison between T2-weighted FSE SPIR and GE MTC.

PURPOSE: To compare two different MR sequences to tissue signal suppression in the study of patellar cartilage abnormalities. MATERIALS AND METHODS: We examined 26 patients with magnetic resonance (MR) imaging: sequences included spectral presaturation with inversion recovery (SPIR), with fat suppression and T2-weighted images, magnetization transfer contrast (MTC) sequences, T1-weighted and T2-weighted spin-echo sequences. All patients underwent conventional knee arthroscopy and in all patients a hyaline cartilage lesion was assessed in three articular zones: the patellar medial facet, the lateral facet and the patellar crista. Was assessed 78 articular facets. The lesions were classified using a standard arthroscopic grading system adapted to MR imaging: normal cartilage that corresponds to the grade 0 according to the Noyes grading system, low grade lesions that correspond to the grade I e IIa and high grade lesions that correspond to grades IIb and III. The arthroscopic results were compared with MR images. We assessed the MR diagnostic accuracy, sensitivity, specificity and MR positive predictive value and negative predictive value of the two sequences taking into consideration total lesions, and high-grade and low grade lesions separately. RESULTS: Twenty-four low grade lesions (16 grade I e 8 grade IIa) and 18 high grade lesions (10 grade IIb e 8 grade III) were diagnosed by arthroscopy. Regarding low grade and high-grade lesions together, the accuracy was 77% for MTC sequences and 90% for SPIR sequences. In identifying low-grade lesions, the sensitivity was 88% for SPIR sequence and 42% for MTC sequences. Specificity for the detection of all lesions was 89% for the SPIR sequences and 94% for the MTC sequences. The SPIR sequence visualised water content abnormalities in degenerating cartilage, which are representative of low-grade lesions. The sensitivity of the sequence enabled us to obtain improved contrast for detecting cartilage surface irregularities. The MTC sequences allowed us to grade high-grade lesions susceptible to surgery and small cartilage defects in the presence of joint fluid. The MTC sequences were insufficient in the diagnosis of early stages of chondromalacia because the suppression of the signal of bonded water reduced the contrast among areas of articular cartilage with different water content. For this reason cartilage oedema and early superficial fibrillation were not identified. CONCLUSIONS: In our experience the SPIR sequence proved superior to the MTC sequence in the identification of low grade lesions of the patellar cartilage. The overall value of such sequences in the study of articular pathology also needs to be assessed in the others sites where the articular cartilage is thinner and surfaces more curvilinear.

Alterations in hepatic uptake and distribution of organ-specific superparamagnetic MRI contrast media: clinical findings and classification according to pathogenesis.

PURPOSE: The aim of this study was to classify the alterations in the liver uptake and distribution of superparamagnetic contrast media that could potentially lead to diagnostic errors. These alterations, referred to as SPIO-LUDA for convenience, may be caused by a variety of disorders, such as cirrhosis, vascular thrombosis, hepatitis and liver steatosis, that interfere with the normal uptake of the contrast material. These conditions can give rise to focal or diffuse areas of hyperintensity or hypointensity which may mimic the presence of neoplastic lesions or hinder the detection or characterisation of neoplasms. MATERIALS AND METHODS: We retrospectively reviewed the hepatic MR examinations of 412 patients performed to detect hepatocellular carcinoma in 349 cases and metastases in 63 cases, with the aim of identifying conditions corresponding to the definition of SPIO-LUDA. All the examinations were performed using a 1.5 Tesla MR unit with SE and GE sequences, T1 and T2 weighted images, and SPIO as a contrast agent, in 402 cases ferumoxide (Endorem, Guerbet) and in 10 cases SHU-555-A (Resovist, Schering). The SPIO-LUDA were classed into two groups: due to reduced uptake (cell replacement, reduced vascular flow and cellular inhibition) and due to increased uptake (Kupffer cell hyperactivity or increased vascularity). From a quantitative point of view we evaluated the percentage of signal loss (PSIL) of the SPIO-LUDA relative to the surrounding healthy parenchyma, as an expression of increase or reduced uptake of contrast material. RESULTS: In 54 patients we identified potentially misleading SPIO-LUDA: 41 were due to reduced uptake and 13 to increased uptake. In 16 cases, all of which cases of reduced uptake, the alteration significantly limited the diagnostic effectiveness of the MR examination. The reduced-uptake SPIO-LUDA were caused by fibrosis in 31 cases, by portal vein thrombosis in 3, by suprahepatic vein thrombosis in 2, by peritumoural vascular shunts in 3 and by hepatitis in 2. The increased-uptake SPIO-LUDA were caused by focal steatosis in 2 cases and by dysplastic nodules in cirrhosis in 11. The reduced-uptake SPIO-LUDA exhibited 30% lower PSIL values than the normal liver (range 15-45%); the increased-uptake SPIO-LUDA displayed 19% higher PSIL values than the surrounding liver (range 15-23%). Out of a total of 412 patients, the alteration of SPIO uptake was so severe as to prevent detection or exclusion of focal lesions in 4% of cases. CONCLUSIONS: SPIO-LUDA constitute a diagnostic challenge. The recognition and correct interpretation of these alterations are fundamental for avoiding confusion with other diseases and to obtain further clues for the interpretation of abnormal patterns detected at MRI or other imaging modalities.

[MRI in ACL reconstructive surgery with PDLLA bioabsorbable interference screws: evaluation of degradation and osteointegration processes of bioabsorbable screws].

PURPOSE: Anterior cruciate ligament (ACL) reconstructive surgery has seen significant progress since bioabsorbable interference screws have replaced synthetic metallic screws for ligament graft fixation within the femoral and tibial osseous tunnel. Our study compared the MR images of patients who underwent ACL reconstruction using bioabsorbable interference screws with those of patients who underwent ACL reconstruction using metallic screws to evaluate the MR aspects of degradation and osteointegration processes of bioabsorbable interference screws post-operatively. MATERIALS AND METHODS: Between September 1999 and December 2002 we performed MRI on 40 patients who underwent arthroscopic ACL reconstruction with patellar tendon auto-graft using PDLLA bioabsorbable screws in 35 cases and metallic screws in 5 cases. After surgery, all patients underwent an intensive rehabilitation programme along with clinical evaluation using the standard knee ligament evaluation form of the International Knee Documentation Committee (IKDC) and radiological examinations. MR studies were performed 1, 2 and 3 years post-operatively using a 0.5-Tesla MR scanner with T1- and T2*-weighted and STIR sequences. RESULTS: Thirty-three patients were clinically classified as group A IKDC (full return to sports activity) and 7 patients as group B IKDC. No foreign-body reaction was found in patients treated with bioabsorbable interference screws, both from a clinical point of view and from laboratory exams. Ferromagnetic artefacts were found in all patients treated with metallic interference screws. In patients with bioabsorbable interference screws, degradation of the screws and absence of significant artefacts allowed correct evaluation of the signal of the reconstructed ligament throughout its length, the osseous tunnels and the joint cavity. In 34 of 35 patients with bioabsorbable interference screws, the screw could not be detected due to complete degradation. In 8, 12 and 4 cases, a small cyst-like formation due to screw hydrolysis was present at the screw site within 1, 2 and 3 years from surgery respectively. Only in 4 cases was the process of osteointegration of the screw and bone plug complete 3 years after the operation, with consequent restoration of bone morphology. DISCUSSION AND CONCLUSIONS: The use of bioabsorbable interference screws is a valuable alternative to synthetic metallic fixation implants as the absence of artefacts allows correct post-operative MR follow-up. MRI is the only technique able to visualize all the portions of the transplant and to evaluate the healing process. Bioabsorbable interference screws usually degrade within one year. However, full osteointegration requires a long time and may not be complete 3 years after surgery. The presence of cyst-like formations at the screw site has to be regarded as a normal feature of the screw degradation process. Therefore, the use of bioabsorbable interference screws is recommended as it enables MR follow-up of the knee after ACL reconstruction.

Tibial plateau fractures: evaluation with multidetector-CT.

PURPOSE: To evaluate the role of Multislice CT (MSCT) in classifying tibial plateau fractures and deciding on the appropriate therapeutic treatment compared to conventional radiology. MATERIALS AND METHODS: Twenty-five patients with a clinical diagnosis of tibial plateau fracture were studied with plain film and MSCT. The CT images were reconstructed with MPR and 3D technique and the fractures classified according to the Swiss AO-ASIF classification. The following radiographic and CT parameters were used: fracture location and size, number of fragments or degree of depression of fracture; plateau area involved; surgical access; degree of osteoporosis and bone tissue loss. RESULTS: The plain film and MSCT classification showed agreement in 48% of cases and disagreement in 52%. MSCT better demonstrated disruption of the tibial plateau surface and showed a larger number of fragments. In 60% of patients the CT features led the orthopaedist to modify the treatment. In three patients CT demonstrated bone tissue loss, suggesting for bone graft. In four patients CT showed alteration of the bone architecture and suggested the use of different material for osteosynthesis. Compared to axial CT, the MSCT MPR and 3D reconstructions enabled a more accurate assessment of plateau depression, and of rotation and separation of the fragments. The 3D technique proved better than MPR in evaluating rotation of fractured fragments as it provides an overall view as well as the possibility of rotating the bone segments. CONCLUSIONS: MSCT and 3D reconstructions are very useful for classifying tibial plateau fractures and for preoperative assessment. Patients with clinical evidence of fracture might benefit from an examination with CT instead of conventional radiology.

Aspects of Magnetic Resonance in the surgical treatment of osteochondral lesions of the knee.

AIM: To assess the magnetic resonance (MR) appearance of knee cartilage chondroplasty procedures and their evolution in order to evaluate the usefulness of the method in monitoring postoperative rehabilitation. MATERIALS AND METHODS: Sixty-two patients treated with knee chondroplasty for high-grade cartilage injuries (Noyes' stages II and III) were examined with MR. Forty patients were treated with abrasion chondroplasty, fifteen with osteochondral graft in the injury site and seven with the matrix-induced autologous chondrocyte transplant technique. All patients were operated on by the same orthopaedic team and examined with the same MR protocol. The MR follow-up was performed six months and one year after surgery in the patients treated with abrasion chondroplasty and osteochondral graft, and one week, three months and one year after surgery in the patients treated with cartilage transplant. In the patients treated with abrasion chondroplasty we assessed the fibrocartilage repair and the subchondral bone features, in the patients treated with osteochondral graft we examined the cartilage, the subchondral bone and the graft borders, while in the patients treated with cartilage transplant we evaluated the features and the evolution of the transplant and the subchondral bone. Arthrosynovitis was assessed in all patients. In seven patients a cartilage repair biopsy was performed in arthroscopy. RESULTS: In all the patients MR imaging proved useful in monitoring the chondroplasty. In the patients treated with abrasion chondroplasty the cartilage repair appeared as a hypointense non-homogeneous irregular strip of tissue that replaced the articular surface. The subchondral bone was sclerotic with some geodes. In the later examination the repair was unchanged. In the patients treated with osteochondral graft the articular cartilage was similar to the adjacent hyaline cartilage, although more non-homogeneous. The subchondral bone was sclerotic and in three cases oedematous. In four cases the graft extended beyond the articular border. In the cartilage transplant the matrix appeared as a hypointense stripe after a week due to hydration and it had thinned with signal reduction in the later follow-ups. In the cases with unfavourable clinical evolution the subchondral bone was oedematous and sclerotic in the later examinations. In the cases with unfavourable clinical evolution there was moderate arthrosynovitis, regardless of the chondroplasty technique performed. CONCLUSIONS: MR imaging is useful for monitoring the maturation and the integration of knee chondroplasty and can be proposed as a replacement of arthroscopy for the assessment of postoperative rehabilitation.

MR in the study of knee cartilage pathologies: influence of location and grade on the effectiveness of the method.

PURPOSE: To evaluate the diagnostic effectiveness of magnetic resonance (MR) in knee cartilage pathologies of different regions and grades with the aim of establishing the role of MR in treatment choice. MATERIALS AND METHODS: We enrolled 90 patients who underwent MR and arthroscopy of the knee. To classify cartilage lesions we used a simplified grading system that correlates MR to arthroscopic reports and divides lesions into low and high grades. The MR examinations were performed with a 1.5 T superconducting magnet with a standard protocol to obtain quality images in a short time, using T1-weighted spin-echo sequences, T2* weighted gradient-echo sequences and inversion recovery sequences. The MR diagnostic specificity, sensitivity and accuracy and MR positive predictive value and negative predictive value in identifying and grading the chondral lesions of the femorotibial and patellofemoral compartments were calculated and compared to arthroscopy parameters. RESULTS: The analysis of each grade of chondral lesions reveals an MR accuracy of 94% in high-grade lesions of the femorotibial and patellofemoral compartments and an MR accuracy of 78% in low-grade lesions of patellofemoral compartment and of 70% in low-grade lesions of femorotibial compartment. This result suggests MR is useful for the grading of chondral lesions in clinical practice. CONCLUSIONS: MR diagnostic effectiveness substantially changes according to the different location and grade of chondral lesions. While MR seems to be nearly equivalent to arthroscopy for high-grade lesions subject to surgery, it appears to be less accurate in diagnosing low-grade lesions, in particular femorotibial lesions.