[Osteochondroma and multiple osteochondromas: recommendations on the diagnostics and follow-up with special consideration to the occurrence of secondary chondrosarcoma]

PURPOSE

Osteochondroma represents the most common form of benign bone tumor. Clinical manifestations include deformity of bone, compression of surrounding tissue and vascular or neurological compromise. Osteochondromas may be solitary (solitary osteochondroma, SO) or multiple (multiple osteochondromas MO). Recurrence after surgery is a known problem especially in MO and malignant transformation is rare but more common in MO than in solitary cases. Reliable recommendations regarding diagnostics and clinical follow-up are currently lacking.

PATIENTS AND METHODS

A comprehensive literature review and a review of own patient files with SO/MO treated between 2000 and 2011 in this hospital were performed. The age of patients at diagnosis, tumor localization, clinical aspects, recurrence and the risk of malignant transformation in secondary (i.e. epiexostotic) chondrosarcoma were analyzed. The follow-up including patients who received surgery ranged between 2 and 127 months for patients with SO and between 2 and 84 months for MO.

RESULTS

A total of 39 patients with SO from this hospital were included in the study. Out of 36 patients who received surgery 3 recurrences were registered after an average time of 62 months. In addition, 11 patients with MO were identified and all received surgery. In 5 out of 11 cases recurrences occurred after an average time of 20.6 months. Secondary chondrosarcomas were not recorded in this series. According to the literature an increased risk of malignant transformation was found for osteochondromas of the axial skeleton, in the proximal aspect of the extremities, as well as for recurrent tumors and for MO. Pain and/or increase in size of lesions after skeletal maturation were the most common clinical signs of transformation. There was a wide time interval between the initial diagnosis and the development of secondary chondrosarcoma. In MO secondary chondrosarcoma has been described before skeletal maturity.

CONCLUSIONS

The risk of malignant transformation of SO is generally low. Axial lesions as well as recurrent osteochondromas and MO seem to have an increased risk of malignant transformation. The follow-up, requiring sufficient primary diagnostics, includes regular self-control and can usually be clinically carried out in more peripherally located lesions but in certain cases supplementary X-ray imaging is needed. In cases of anatomical regions which are more difficult to access manually, follow-up examination by magnetic resonance imaging (MRI) is the method of choice. Especially MO patients seem to benefit from long-term follow-up: when the tumor is located in the trunk and in (proximal) long bones MRI or whole-body MRI, respectively, should be performed once a year after skeletal maturity because of the higher risk of malignant transformation in these patients.

Video sequence compared to conventional freeze image documentation: a way to improve the sonographic assessment of breast lesions?

PURPOSE

To compare video sequence and conventional freeze image documentation of breast ultrasound findings with respect to lesion assessment and the diagnostic power of established ultrasound characteristics.

MATERIALS AND METHODS

Digitally stored freeze images and corresponding video sequences of 50 breast lesions were randomly arranged and interpreted by eight investigators with breast ultrasound training and experience. Established ultrasound criteria were documented on a standardized classification form for every lesion. The investigators were blinded to the clinical and radiological findings, patient characteristics including age, and lesion histology. Statistical analysis compared both groups and correlated the results with the lesion histology. A receiver operating characteristics (ROC) analysis was performed to evaluate the diagnostic performance of ultrasound criteria in lesions documented by video sequences compared to freeze images.

RESULTS

Breast lesions were assessed almost identically in video sequences and freeze images. Only the features echogenic halo, orientation, and margin varied among both groups. The dynamic features compressibility and mobility were highly statistically significant correlated with the lesion histology in the video sequence interpretation (p < 0.0001). ROC analysis revealed almost identical diagnostic accuracy in both groups (area under the curve 0.719 for video sequences and 0.762 for freeze images).

CONCLUSION

Video sequences are an appropriate tool to document lesions in breast ultrasound. In contrast to our hypothesis, however, this tool did not improve the diagnostic power of established ultrasound characteristics compared to freeze image documentation.

Artifact reduction in moving-table acquisitions using parallel imaging and multiple averages

Two-dimensional (2D) axial continuously-moving-table imaging has to deal with artifacts due to gradient nonlinearity and breathing motion, and has to provide the highest scan efficiency. Parallel imaging techniques (e.g., generalized autocalibrating partially parallel acquisition GRAPPA)) are used to reduce such artifacts and avoid ghosting artifacts. The latter occur in T(2)-weighted multi-spin-echo (SE) acquisitions that omit an additional excitation prior to imaging scans for presaturation purposes. Multiple images are reconstructed from subdivisions of a fully sampled k-space data set, each of which is acquired in a single SE train. These images are then averaged. GRAPPA coil weights are estimated without additional measurements. Compared to conventional image reconstruction, inconsistencies between different subsets of k-space induce less artifacts when each k-space part is reconstructed separately and the multiple images are averaged afterwards. These inconsistencies may lead to inaccurate GRAPPA coil weights using the proposed intrinsic GRAPPA calibration. It is shown that aliasing artifacts in single images are canceled out after averaging. Phantom and in vivo studies demonstrate the benefit of the proposed reconstruction scheme for free-breathing axial continuously-moving-table imaging using fast multi-SE sequences.

Diagnostic accuracy of MRI for preoperative staging of pancreatic carcinoma: tendency for understaging

OBJECTIVE

To evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) for preoperative staging in pancreatic carcinoma.

MATERIALS AND METHODS

MRI investigations, including MR-angio and MR-cholangiopancreatography (MRCP) of 19 patients who underwent surgery for pancreatic carcinoma were retrospectively evaluated by two radiologists. The size, localization of the tumor and possible infiltration of neighboring organs, as well as the presence of enlarged lymph nodes, were determined to define a preoperative, radiological TN stage. Lymph node metastasis was defined as peripancreatic lymphoma greater than 10 mm. Our findings were correlated to postoperative diagnosis.

RESULTS

The T-stage was correctly evaluated in 52.6% of the cases (10/19). Understaging took place in 31.6% (6/19) and overstaging in 15.8% (3/19). In three cases of understaging, a micro-infiltration of the peripancreatic tissue was not visible in MRI. Pathologically enlarged lymph nodes were correctly found in 63.2% of the cases (12/19). Overstaging took place in 21.1% of the cases (4/19) and understaging in 15.8% (3/19).

CONCLUSION

MRl for preoperative staging of pancreatic carcinoma showed a tendency to understage tumor size in this study population. Especially in cases of small tumor size, micro-infiltration of peripancreatic tissue or the common bile duct may not be detected by MRI. Concerning N-stage, the 95% confidence interval reveals a distribution of over- and understaged.

Using Receiver Operating Characteristic Methodology to Evaluate the Diagnostic Quality of Radiography on Paper Prints Versus Film

OBJECTIVE

The aim of this study was to compare the diagnostic quality of paper prints with film copies in a sample of observers who were trying to detect small coin lesions on radiographs of a phantom.

MATERIALS AND METHODS

The phantom consisted of 60 high-contrast and 60 low-contrast test objects, half of which had holes in them. Diameter and depth of the holes varied from 0.5 mm to 2 mm. Fifteen radiographs were obtained from different areas of the test objects. Film copies and paper prints were made using high-quality printers. Five observers independently evaluated 1,800 high-contrast and 1,800 low-contrast images. Data were evaluated using the well-established receiver operating characteristic methodology.

RESULTS

The mean area under the curve rated 0.863 for paper prints (0.859 for high contrast and 0.860 for low contrast) and 0.926 for laser films (0.937 for high contrast and 0.913 for low contrast). The difference between the two imaging techniques was statistically significant for both high- and low-contrast lesions (p < 0.05).

CONCLUSION

Detection of small coin lesions on radiographs of a phantom was significantly less sensitive on paper prints than on film. We found paper prints less acceptable for the diagnosis of small-sized lesions.

[Image quality of paper prints compared to film copies in CT investigations]

PURPOSE

Evaluation of image quality of paper prints in routine CT investigations.

METHOD

The image quality of paper prints from 104 CT scans of daily routine investigations was analysed by three observer three observers according to a five-point ranking scale for contrast, grey level, spatial resolution, and subjective confidence in correct evaluation. Each study was rated "acceptable" or "not acceptable for documentation".

RESULTS

In 312 ratings the mean grade for contrast was 2.7, for grey levels 3.2, and for spatial resolution 3.3. Grades ranged from 1 = very good to 5 = insufficient. Subjective confidence in correct evaluation was rated as "certain" in 77.4 %, "likely" in 18.4 % and "impossible to evaluate" in 4.2 % of cases. 93.7 % of printed CT images were rated "acceptable for documentation".

CONCLUSION

Image quality of paper prints does not reach the quality of laser films concerning its contrast, grey levels, and spatial resolution. Nevertheless, paper prints are acceptable for documentation of findings in most CT investigations. A high confidence in correct evaluation was found. Limitations are found in documentation of small coin lesions of the lung and ischemic lesions of the neurocranium.

Extracellular nucleotides regulate cellular functions of podocytes in culture

Extracellular nucleotides are assumed to be important regulators of glomerular functions. This study characterizes purinergic receptors in podocytes. The effects of purinergic agonists on electrophysiological properties and the intracellular free Ca(2+) concentration of differentiated podocytes were examined with the patch-clamp and fura 2 fluorescence techniques. mRNA expression of purinergic receptors was investigated by RT-PCR. Purinergic agonists depolarized podocytes. Purinergic agonists similarly increased intracellular free Ca(2+) concentration of podocytes. The rank order of potency of various nucleotides on membrane voltage and free cytosolic calcium concentration was UTP approximately UDP > [adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S)] > ATP > 2-methylthioadenosine 5'-triphosphate (2-MeS-ATP) > 2'- and 3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP) > ADP-beta-S. alpha,beta-Me-ATP was without effect. In the presence of UTP, BzATP did not cause an additional depolarization of podocytes. Incubation of cells with ATP or BzATP did not induce lactate dehydrogenase release. In RT-PCR studies, mRNAs of the P2Y(1), P2Y(2), P2Y(6), and P2X(7) receptors were detected within glomeruli and podocytes. The data indicate that extracellular nucleotides modulate podocyte function mainly by an activation of both P2Y(2) and P2Y(6) receptors.