Accuracy of radiography in grading and tissue-specific diagnosis--a study of 200 consecutive bone tumors of the hand

OBJECTIVE

To determine the usefulness of radiography and magnetic resonance imaging in differentiating benign from malignant bony tumors of the hand and in making a tissue-specific diagnosis.

DESIGN

Two hundred consecutive bony tumors of the hand, the details of which originated from a national databank, were studied in a prospective way by radiography (100%) and by MRI (25%). All tumors were graded on a five-point scale, from certainly benign to certainly malignant, using location and morphology as diagnostic parameters. For all tumors a tissue-specific diagnosis was made, by the proposal of three possibilities in decreasing order of probability. Histological diagnosis was made by peer review, according to the WHO classification.

RESULTS

By the combining of "certainly" and "probably" benign (grades I and II) and "certainly" and "probably" malignant (grades IV and V), a correct grading was obtained in 165 (82.5%) of the cases (154 of the 173 benign and 11 of the 27 malignant tumors). A correct tissue-specific diagnosis was included in the three proposed differentials in 87.5%. MRI confirmed a correct diagnosis made on radiography in 72% and improved the grading capability by correctly upgrading malignant tumors and downgrading benign tumors in, respectively, 8% and 12%. The capability to obtain a tissue-specific diagnosis improved with change of an incorrect diagnosis on radiography to a correct one on MRI in 12 cases (24%).

CONCLUSION

Subjective (semiquantitative) grading on radiography by an expert group proved to be excellent when compared with the results of a quantitative analysis of individual grading parameters. Multiple logistic regression analysis of these parameters resulted in a grading formula containing only six variables. The additional value of MRI in grading was amply demonstrated. Already high accuracy of radiography, in making a tissue-specific diagnosis, improved substantially after the performance of MRI.

Helical computed tomography and alternative diagnosis in patients with excluded pulmonary embolism

OBJECTIVE

A clinical diagnosis of pulmonary embolism (PE) is confirmed objectively in 20-30% of patients. Helical computed tomography (CT) can allow an alternative diagnosis to be made. The frequency and validity of alternative diagnoses on helical CT in consecutive patients presenting with clinically suspected PE was assessed.

PATIENTS AND METHODS

In all 512 prospectively analyzed patients helical CT scan was performed, and apart from presence or absence of PE, pathologic changes in lung parenchyma, mediastinum, cardiovascular system, pleura and skeleton were recorded. When possible an alternative diagnosis was given and compared with the final diagnosis after 3 months follow-up.

RESULTS

In 130 patients (25.4%) PE was excluded and an alternative diagnosis considered likely. In 123 of the 130 patients (94.6%) this diagnosis was unchanged at 3 months follow-up. The diagnoses included pneumonia (n = 67), malignancy (n = 22), pleural fluid (n = 10), cardiac failure (n = 10), COPD (n = 6) and a variety of other causes (n = 15). The diagnosis changed at follow-up in seven patients (5.4%). An initial diagnosis of pneumonia changed to malignancy in two patients and to pleuritis and cardiac failure in one patient each. In two other patients malignancy and chronic obstructive pulmonary disease (COPD) were ruled out and the diagnosis changed to pneumonia. In one patient the final diagnosis remained unknown after an initial suspicion of malignancy.

CONCLUSION

In clinically suspected PE helical CT allows a reliable alternative diagnosis to be made in 25.4% of patients. This feature is an unique advantage in comparison with other diagnostic tests and supports the decision of taking helical CT as first line test in suspected PE.

Clinical consequences of bone bruise around the knee

The aim of this study is to evaluate the relation between bone bruise and (peri-)articular derangement and to assess the impact of bone bruise on presentation and short term course of knee complaints. We recorded MR abnormalities in 664 consecutive patients with sub-acute knee complaints. Patients were divided in four groups: patients with and without intra-articular knee pathology, subdivided in patients with and without bone bruise. We assessed function and symptoms at the time of MR and 6 months thereafter. Bone bruises were diagnosed in 124 of 664 patients (18.7%). Patients with bone bruise had significantly more complete ACL, lateral meniscal, MCL and LCL tears. Both with and without intra-articular pathology patients with bone bruise had a significantly poorer function at the time of MR (Noyes score of, respectively, 313.21 versus 344.81 and 306.98 versus 341.19). Patients with bone bruise and intra-articular pathology showed significantly more decrease in activity (decrease of Tegner score from 6.28 to 2.12 versus 5.70-2.55). At 6 months there were no significant differences in clinical parameters between the four groups. We concluded that bone bruise in combination with MCL tear is an important cause of initial clinical impairment in patients with sub-acute knee complaints. Clinical improvement within 6 months is more pronounced than in patients without bone bruise.

MRI of adamantinoma of long bones in correlation with histopathology

OBJECTIVE

The purposes of this retrospective study were to assess specific MRI features of adamantinoma, including classic adamantinoma and its osteofibrous dysplasia-like variant, and to assess the role of adamantinoma in surgical planning.

MATERIALS AND METHODS

MR images of 22 patients with histologically proven adamantinoma, subtyped according to defined criteria, were analyzed, with emphasis on morphologic features, signal intensities, and enhancement parameters. Intra- and extraosseous tumor extent was determined. In all patients, examination of the corresponding resected specimens was performed with regard to tumor extent and presence of multicentricity. Moreover, radiographs were reviewed, and radiographic features derived from the literature were determined.

RESULTS

All tumors were primarily localized in the tibia diaphysis (including one patient with additional lesions in the fibula), most frequently in the anterior cortical bone (19/22) with extension toward the bone marrow in 12 patients. We distinguished two morphologic patterns: a solitary lobulated focus versus a pattern of multiple small nodules in one or more foci. Separated tumor foci, defined as foci of high signal intensity on either T2-weighted images or T1-weighted contrast-enhanced images, interspersed with normal-appearing cortical or spongious bone were seen in six patients. All tumors showed intense and homogeneous static enhancement, but there was no uniform dynamic enhancement pattern. No relationship between MRI features and histologic subtype of adamantinoma was found.

CONCLUSION

Some uniform MRI characteristics, along with those of radiography, may contribute to the diagnosis of adamantinoma; however, these are not related to the histologic subtype. MRI is pivotal for precise locoregional staging, especially for depiction of distant cortical foci, soft tissue, and intramedullary extension and thus is useful for determining tumor-free margins and strategies for reconstructive surgery.

The relationship between the MRI features of mild osteoarthritis in the patellofemoral and tibiofemoral compartments of the knee

The aim of this work was to demonstrate the relationship between osteoarthritic changes seen on magnetic resonance (MR) images of the patellofemoral (PF) or tibiofemoral (TF) compartments in patients with mild osteoarthritis (OA) of the knee. MR images of the knee were obtained in 105 sib pairs (210 patients) who had been diagnosed with OA at multiple joints. Entry criteria included that the degree of OA in the knee examined should be between a Kellgren and Lawrence score of 2 or 3. MR images were analyzed for the presence of cartilaginous lesions, bone marrow edema (BME) and meniscal tears. The relationship between findings in the medial and lateral aspects of the PF and TF compartments was examined. The number of cartilaginous defects on either side of the PF compartment correlated positively with number of cartilaginous defects in the ipsilateral TF compartment (odds ratio, OR, 55, confidence interval, CI, 7.8-382). The number of cartilaginous defects in the PF compartment correlated positively with ipsilateral meniscal tears (OR 3.7, CI 1.0-14) and ipsilateral PF BME (OR 17, CI 3.8-72). Cartilaginous defects in the TF compartment correlated positively with ipsilateral meniscal tears (OR 9.8, CI 2.5-38) and ipsilateral TF BME (OR 120, CI 6.5-2,221). Osteoarthritic defects lateralize or medialize in the PF and TF compartments of the knee in patients with mild OA.

MRI assessment of knee osteoarthritis: Knee Osteoarthritis Scoring System (KOSS)--inter-observer and intra-observer reproducibility of a compartment-based scoring system

OBJECTIVE

To develop a scoring system for quantifying osteoarthritic changes of the knee as identified by magnetic resonance (MR) imaging, and to determine its inter- and intra-observer reproducibility, in order to monitor medical therapy in research studies.

DESIGN AND PATIENTS

Two independent observers evaluated 25 consecutive MR examinations of the knee in patients with previously defined clinical symptoms and radiological signs of osteoarthritis. We acquired on a 1.5 T system: coronal and sagittal proton density- and T2-weighted dual spin echo (SE) images, sagittal three-dimensional T1-weighted gradient echo (GE) images with fat suppression, and axial dual turbo SE images with fat suppression. Images were scored for the presence of cartilaginous lesions, osteophytes, subchondral cysts, bone marrow edema, and for meniscal abnormalities. Presence and size of effusion, synovitis and Baker's cyst were recorded. All parameters were ranked on a previously defined, semiquantitative scale, reflecting increasing severity of findings. Kappa, weighted kappa and intraclass correlation coefficient (ICC) were used to determine inter- and intra-observer variability.

RESULTS

Inter-observer reproducibility was good (ICC value 0.77). Inter- and intra-observer reproducibility for individual parameters was good to very good (inter-observer ICC value 0.63-0.91; intra-observer ICC value 0.76-0.96).

CONCLUSION

The presented comprehensive MR scoring system for osteoarthritic changes of the knee has a good to very good inter-observer and intra-observer reproducibility. Thus the score form with its definitions can be used for standardized assessment of osteoarthritic changes to monitor medical therapy in research studies.

Soft-Tissue Tumors: Value of Static and Dynamic Gadopentetate Dimeglumine–enhanced MR Imaging in Prediction of Malignancy

PURPOSE

To prospectively evaluate static and dynamic gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging relative to nonenhanced MR imaging in differentiation of benign from malignant soft-tissue lesions and to evaluate which MR imaging parameters are most predictive of malignancy, with associated interobserver variability.

MATERIALS AND METHODS

One hundred forty consecutive patients (78 male patients [median age, 51 years], 62 female patients [median age, 53 years]) with a soft-tissue mass underwent nonenhanced static and dynamic contrast material-enhanced MR imaging. Diagnosis was based on histologic findings in surgical specimens (86 of 140), findings at core-needle biopsy (43 of 140), or results of all imaging procedures with clinical follow-up (11 of 140). Multivariate logistic regression analysis was used to identify the best combination of MR imaging parameters that might be predictive of malignancy. Subjective overall performance of two observers was evaluated with receiver operating characteristic analysis.

RESULTS

For subjective overall diagnosis, area under the receiver operating characteristic curve, a measure for diagnostic accuracy, was significantly larger for combined nonenhanced and contrast-enhanced MR imaging than it was for nonenhanced MR imaging alone, with no significant difference between observers. Multivariate analysis of all lesions revealed that combined nonenhanced static and dynamic contrast-enhanced MR imaging parameters were significantly superior to nonenhanced MR imaging parameters alone and to nonenhanced MR imaging parameters combined with static contrast-enhanced MR imaging parameters in prediction of malignancy. The most discriminating parameters were presence of liquefaction, start of dynamic enhancement (time interval between start of arterial and tumor enhancement), and lesion size (diameter). Results for extremity lesions were the same, with one exception: With dynamic contrast-enhanced MR imaging parameters, diagnostic performance of one observer did not improve.

CONCLUSION

Static and dynamic contrast-enhanced MR imaging, when added to nonenhanced MR imaging, improved differentiation between benign and malignant soft-tissue lesions.

Osteoid osteoma: factors for increased risk of unsuccessful thermal coagulation

PURPOSE

To retrospectively identify risk factors that may impede a favorable clinical outcome after thermocoagulation for osteoid osteoma.

MATERIALS AND METHODS

Informed consent (permission for the procedure and permission to use patient data for analysis) was obtained from all patients who met study criteria, and institutional review board did not require approval. Analysis included age, sex, size and location of osteoid osteoma, presence of calcified nidus, number of needle positions used for coagulation, coagulation time, accuracy of needle position, learning curve of radiologist, and previous treatment in 95 consecutive patients with osteoid osteoma treated with thermocoagulation. With chi(2) analysis, Fisher exact test, or unpaired Student t test and logistic regression analysis, 23 unsuccessfully treated patients were compared with 72 successfully (pain-free) treated patients.

RESULTS

Parameters associated with decreased risk for treatment failure were advanced age (mean age, 24 years in treatment success group vs 20 years in treatment failure group) and increased number of needle positions during thermocoagulation. Estimated odds ratios were, respectively, 0.93 (95% confidence interval: 0.88, 0.99) and 0.10 (95% confidence interval: 0.02, 0.41). Patients with a lesion of 10 mm or larger seemed at risk for treatment failure (odds ratio = 2.68), but the 95% confidence interval of 0.84 to 8.52 included the 1.00 value. Needle position was inaccurate in nine of 23 patients with treatment failure; only one needle position was used in eight of these nine patients. Lesion location, calcification, sex, coagulation time, radiologist's learning curve, and previous treatment were not risk factors.

CONCLUSION

Multiple needle positions reduce the risk of treatment failure in all patients and should especially, but not exclusively, be used in large (> or =10-mm) lesions or lesions that are difficult to engage to reduce the risk for unsuccessful treatment.

Quantitative analysis of focal masses at MR imaging: a plea for standardization

PURPOSE

To assess the effects of changing analytic method variables on the signal intensity (SI) difference-to-noise ratios (SDNRs) for the contrast between lesions and background organs depicted on magnetic resonance (MR) images and to propose a standardized analytic method for the quantitative analysis of focal masses seen at MR imaging.

MATERIALS AND METHODS

The SIs of 48 liver metastases (originating from colorectal cancer) in 20 patients, the surrounding liver parenchyma, and the background noise were measured on T2-weighted MR images. All 2000 and 2001 issues of the American Journal of Roentgenology, the Journal of Magnetic Resonance Imaging, Magnetic Resonance Imaging, and Radiology were searched for articles describing quantitative analyses. SDNRs were calculated by using formulas from these articles and various region-of-interest (ROI) locations to measure metastasis and background noise SIs. The Wilcoxon signed rank test was used to compare the various SDNR calculations.

RESULTS

In 34 articles in which quantitative analyses of focal masses are described, the reported SDNRs were calculated with four different formulas. The SDNRs for our study material calculated with the four formulas reported in the literature differed grossly in both number and unit. The SDNRs for ROIs encompassing the entire metastasis differed significantly (P =.034) from the SDNRs for ROIs in a homogeneous area of the metastasis margin. Differences in SDNRs between various noise ROI locations were significant (P <.022).

CONCLUSION

Slight changes in the variables of quantitative analysis of focal masses had marked effects on reported SDNRs. To overcome these effects, the use of a standardized method involving one formula, a lesion ROI in a homogeneous area at the metastasis margin, and a background noise ROI along the phase-encoding axis in the air (including systematic noise) is proposed for the quantitative analysis of findings on magnitude MR images.

Rheumatoid Arthritis: Epidural Enhancement as an Underestimated Cause of Subaxial Cervical Spinal Stenosis

PURPOSE

To assess the frequency and site of subaxial spinal canal stenosis due to enhancing tissue in patients with rheumatoid arthritis.

MATERIALS AND METHODS

Data from 33 consecutive patients with rheumatoid arthritis were evaluated; these patients had undergone 1.5-T magnetic resonance imaging following gadolinium chelate administration, in combination with a frequency selective fat-suppression technique. Stenosis and enhancement were scored for each of six cervical spinal levels and were compared with results in a control population consisting of 16 patients with degenerative disease. Enhancement was scored as superficial or deep on the anterior and posterior sides from the cervical spinal cord. Differences between patient groups were tested by using the chi(2) test for trend and the Fisher exact test.

RESULTS

No significant difference was found in the frequency or severity of subaxial stenosis between rheumatoid arthritis and degenerative disease. Deep epidural enhancement was observed more often with rheumatoid arthritis than with degenerative disease both anterior (25 of 33 patients vs seven of 16 patients, respectively; P <.001) and posterior (24 of 33 patients vs two of 16 patients, respectively; P =.001) to the spinal cord. Enhancing stenosing tissue in rheumatoid arthritis frequently occurred anterior and posterior at the same time and at the same level, with segmental cufflike extension of enhancing tissue around the dural sac. Stenosing tissue enhanced more frequently with rheumatoid arthritis than with degenerative disease (22 of 33 vs four of 16 patients, respectively; P =.008).

CONCLUSION

In patients with rheumatoid arthritis, subaxial stenosis is frequently caused by enhancing epidural tissue. This enhancing tissue presumably represents pannus.

Magnetic resonance imaging of knee cartilage using a water selective balanced steady-state free precession sequence

PURPOSE

To compare an optimized water selective balanced steady-state free precession sequence (WS-bSSFP) with conventional magnetic resonance (MR) sequences in imaging cartilage of osteoarthritic knees.

MATERIALS AND METHODS

Flip angles of sagittal and axial WS-bSSFP sequences were optimized in three volunteers. Subsequently, the knees of 10 patients with generalized osteoarthritis were imaged using sagittal and axial WS-bSSFP and conventional MR imaging techniques. We calculated contrast-to-noise ratios (CNR) between cartilage and its surrounding tissues to quantitatively analyze the various sequences. Using dedicated software we compared, in two other patients, the accuracy of cartilage volume measurements with anatomic sections of the tibial plateau.

RESULTS

CNRtotal eff (CNR efficiency between cartilage and its surrounding tissue) using WS-bSSFP was maximal with a 20-25 degrees flip angle. CNRtotal eff was higher in WS-bSSFP than in conventional images: 6.1 times higher compared to T1-weighted gradient echo (GE) images, 5.1 compared to proton-density (PD) fast spin echo (FSE) images, and 4.8 compared to T2-weighted FSE images. The mean difference of cartilage volume measurement on WS-bSSFP and anatomic sections was 0.06 mL compared to 0.24 mL for T1-GE and anatomic sections.

CONCLUSION

A WS-bSSFP sequence is superior to conventional MR imaging sequences in imaging cartilage of the knee in patients with osteoarthritis.

Dynamic contrast-enhanced MR imaging in monitoring response to isolated limb perfusion in high-grade soft tissue sarcoma: initial results

The objective of this study was to evaluate whether dynamic contrast-enhanced MR imaging can determine tumor response and localize residual viable tumor after isolated limb perfusion (ILP) chemotherapy in soft tissue tumors. Twelve consecutive patients, with histologically proven high-grade soft tissue sarcoma, prospectively underwent non-enhanced MR and dynamic contrast-enhanced MR imaging before and after ILP. Tumor volume was measured on non-enhanced MR images. The temporal change of signal intensity in a region of interest on dynamic contrast-enhanced MR images was plotted against time. Start, pattern, and progression of enhancement were recorded. Histopathologic response was defined as complete response if no residual viable tumor was present, partial remission if <50% viable tumor was present, and no change if > or =50% viable tumor was present in the resection specimen. Resected specimens for correlation with histopathology were available for 10 patients; 5 patients had partial remission and 5 had no change. Volume measurements correctly predicted tumor response in 6 of 10 patients. Dynamic contrast-enhanced MR correctly predicted tumor response in 8 of 10 patients. Early rapidly progressive enhancement correlated histologically with residual viable tumor. Late and gradual, or absence of enhancement, was associated with necrosis, predominantly centrally located, or granulation tissue. These preliminary results show that dynamic contrast-enhanced MR imaging offers potential for non-invasive monitoring of response to isolated limb perfusion in soft tissue sarcomas due to identification of residual areas of viable tumor and subsequently may provide clinically useful information with regards to timing and planning of additional surgery. Further prospective studies in a larger patient population is warranted.

Diagnosis of pulmonary embolism with spiral CT as a second procedure following scintigraphy

Our objective was to evaluate, in a routine clinical setting, the role of spiral CT as a second procedure in patients with clinically suspected pulmonary embolism (PE) and abnormal perfusion scan. We prospectively studied the role of spiral CT in 279 patients suspected of PE. All patients started their diagnostic algorithm with chest radiographs and perfusion scintigraphy. Depending on the results of perfusion scintigraphy, patients proceeded to subsequent levels in the algorithm: stop if perfusion scintigraphy was normal; CT and pulmonary angiography if subsegmental perfusion defects were seen; ventilation scintigraphy followed by CT when segmental perfusion defects were seen; and pulmonary angiography in this last group when results of ventilation/perfusion scintigraphy and CT were incongruent. Reference diagnosis was based on normal perfusion scintigraphy, high probability perfusion/ventilation scintigraphy in combination with abnormal CT, or pulmonary angiography. If PE was present, the largest involved branch was noted on pulmonary angiography, or on spiral CT scan in case of a high-probability ventilation/perfusion scan and a positive CT scan. A distinction was made between embolism in a segmental branch or larger, or subsegmental embolism. Two hundred seventy-nine patients had abnormal scintigraphy. In 27 patients spiral CT and/or pulmonary angiography were non-diagnostic and these were excluded for image analysis. Using spiral CT we correctly identified 117 of 135 patients with PE, and 106 of 117 patients without PE. Sensitivity and specificity was therefore 87 and 91%, respectively. Prevalence of PE was 53%. Positive and negative predictive values were, respectively, 91 and 86%. In the high-probability group, sensitivity and specificity increased to 97 and 100%, respectively, with a prevalence of 90%. In the non-high probability-group sensitivity and specificity decreased to 61 and 89%, respectively, with a prevalence of 25%. In a routine clinical setting single-detector spiral CT technology has limited value as a second diagnostic test because of low added value in patients with a high-probability lung scan and low sensitivity in patients with non-high-probability lung scan result.

Metastases of colorectal carcinoma: comparison of soft- and hard-copy helical CT interpretation

PURPOSE

To compare soft- and hard-copy computed tomographic (CT) image interpretation with regard to evaluation time and detection rates for hepatic and extrahepatic colorectal metastases in candidates for liver surgery.

MATERIALS AND METHODS

In 20 patients with a history of colorectal carcinoma, two radiologists independently evaluated CT data sets. Focal hepatic lesions were characterized as benign or malignant by using a five-point scale. In each patient, soft-copy readouts and hard-copy printouts were compared for nonenhanced hepatic, contrast material-enhanced hepatic, and contrast-enhanced extrahepatic data sets. A stopwatch was used to document evaluation time. Ninety-two hepatic metastases and six extrahepatic metastatic recurrences were detected with the standard of reference--surgical, intraoperative ultrasonographic, and histologic findings.

RESULTS

Both observers evaluated the contrast-enhanced hepatic data set significantly faster (P =.026 and.009) by using soft-copy readouts. The contrast-enhanced extrahepatic data set was also evaluated significantly faster (P =.010 and.006) with soft-copy readouts. Detection of hepatic and extrahepatic tumor with soft-copy readouts is not significantly superior to that with hard copies. Detection rates of hepatic metastases for nonenhanced and contrast-enhanced CT for both observers ranged from 50%-80% (46-74 of 92) for soft-copy readouts and 46%-75% (42-69 of 92) for hard copies. Interobserver agreement was highest for contrast-enhanced soft-copy readouts for hepatic metastases.

CONCLUSION

Soft-copy readouts of contrast-enhanced CT data sets for the detection of hepatic metastases and extrahepatic metastatic recurrences were evaluated significantly faster than were hard copies, with at least equal sensitivity and with excellent interobserver agreement.

Hepatic metastases in patients with colorectal cancer: relationship between size of metastases, standard of reference, and detection rates

PURPOSE

To determine the relationship between the size of hepatic metastases, the standard of reference, and the reported detection rate in patients with colorectal cancer.

MATERIALS AND METHODS

With use of a MEDLINE search (January 1994 to January 2001), articles were selected that contained original results on detection of hepatic metastases of colorectal cancer, categorized for size in at least two categories, with use of helical computed tomography (CT), helical CT at arterial portography, or magnetic resonance imaging. Results were compared with the size distribution of hepatic metastases in 47 consecutive patients with colorectal carcinoma, which were detected by using a combination of intraoperative ultrasonography (US) and palpation.

RESULTS

Seven studies met all predefined criteria. Four studies involved intraoperative US in all patients and demonstrated a significant negative correlation (-0.988) between detection rate and fraction of small metastases. These studies had a higher fraction and lower detection rate of small metastases and a lower overall detection rate. A majority (58% [145 of 252]) of metastases in the study population were smaller than 20 mm.

CONCLUSION

Few articles adequately describe the standard of reference and size distribution of hepatic lesions. Hepatic metastases of colorectal cancer are frequently smaller than 20 mm. When the standard of reference is suboptimal, many small metastases are excluded from analysis, and detection rates are therefore inflated.

Osteoid osteoma: clinical results with thermocoagulation

PURPOSE

To determine the clinical results in an unselected group of consecutive patients with osteoid osteoma treated with thermocoagulation.

MATERIALS AND METHODS

In 97 consecutive patients with clinical and/or radiologic evidence of osteoid osteoma at any location, the clinical symptoms were assessed before and after thermocoagulation with computed tomographic guidance. A good response was defined as disappearance of symptoms that were manifested at presentation and attributed to osteoid osteoma. Clinical assessment was performed prior to discharge; within 2 weeks after the procedure; and at 3, 6, 12, and 24 months follow-up. After 24 months, a postal questionnaire was used for assessment.

RESULTS

The mean clinical follow-up after the only or the last thermocoagulation session was 41 months (range, 5-81 months). Response was good after one session of thermocoagulation in 74 (76%) of 97 patients, and the 95% CI was 68% to 85%. Patients with persistent symptoms did well after repeated thermocoagulation (good response in 10 of 12 patients), but results of repeated thermocoagulation were poor in patients with recurrent symptoms (good response in five of 10). The overall success rate after one or two thermocoagulation procedures combined was 92% (89 of 97 patients), and the 95% CI was 86% to 97%. Complications were observed in two patients.

CONCLUSION

Percutaneous thermocoagulation is a safe and effective method for treatment of osteoid osteoma at any location. Repeated thermocoagulation is successful in patients with persistent symptoms.

Effectiveness of MR imaging in selection of patients for arthroscopy of the knee

PURPOSE

To determine the effectiveness of magnetic resonance (MR) imaging in the appropriate identification of those patients with a high clinical suspicion of internal derangements of the knee who require arthroscopic therapy.

MATERIALS AND METHODS

In a prospective multicenter study, MR imaging was performed at 0.5 T in 430 consecutive patients. The sensitivity and specificity of MR imaging in the patients who underwent arthroscopy and the corrected sensitivity and specificity of MR in all the study patients were calculated. For this correction, patients with negative MR and arthroscopic results were considered representative of the patients with negative MR results who were conservatively treated, and the number of the former was doubled. The standard errors of the corrected values were adjusted with the delta method.

RESULTS

At MR imaging, arthroscopy was indicated in 221 patients, 200 of whom underwent arthroscopy. Two hundred nine patients with negative MR imaging results were randomized for arthroscopic (105 patients) or for conservative treatment (104 patients). Of the 105 patients randomized for arthroscopy, 93 actually underwent arthroscopy. Arthroscopic treatment was necessary in 13 of 93 patients with a negative diagnosis at MR imaging. Arthroscopic treatment was necessary in 179 of 200 patients with a positive diagnosis at MR (sensitivity, 93.2%; specificity, 79.2%). Sensitivity and specificity corrected for randomization were 87.3% and 88.4%. Sensitivity and specificity corrected for randomization, respectively, were 84.1% and 94.2% for the diagnosis of medial meniscal tears and 69.5% and 94.5% for the diagnosis of lateral meniscal tears at MR.

CONCLUSION

MR imaging is an effective tool in the selection of patients for arthroscopy from among a general population.

Value of dynamic contrast-enhanced MR imaging in diagnosing and classifying peripheral vascular malformations

OBJECTIVE

Our purpose was to evaluate prospectively whether MR imaging, including dynamic contrast-enhanced MR imaging, could be used to categorize peripheral vascular malformations and especially to identify venous malformations that do not need angiography for treatment.

SUBJECTS AND METHODS

In this blinded prospective study, two observers independently correlated MR imaging findings of 27 patients having peripheral vascular malformations with those of diagnostic angiography and additional venography. MR diagnosis of the category, based on a combination of conventional and dynamic contrast-enhanced MR parameters, was compared with the angiographic diagnosis using gamma statistics. Sensitivity and specificity of conventional MR imaging and dynamic contrast-enhanced MR imaging in differentiating venous from nonvenous malformations were determined.

RESULTS

Excellent agreement between the two observers in determining MR categories (gamma = 0.99) existed. Agreement between MR categories and angiographic categories was high for both observers (gamma = 0.97 and 0.92). Sensitivity of conventional MR imaging in differentiating venous and nonvenous malformations was 100%, whereas specificity was 24-33%. Specificity increased to 95% by adding dynamic contrast-enhanced MR imaging, but sensitivity decreased to 83%.

CONCLUSION

Conventional and dynamic contrast-enhanced MR parameters can be used in combination to categorize vascular malformations. Dynamic contrast-enhanced MR imaging allows diagnosis of venous malformations with high specificity.

Fast magnetic resonance imaging with contrast for soft tissue sarcoma viability

Because dynamic (fast) contrast-enhanced magnetic resonance imaging with its temporal resolution allows evaluation of contrast kinetics of soft tissue sarcomas, its efficacy for defining viable tumor in these neoplasms was studied for three applications: biopsy localization, chemotherapeutic response, and differentiation between recurrence and inflammation after treatment. After conventional T1-weighted and T2-weighted magnetic resonance sequences to localize the lesion, patients had dynamic contrast-enhanced magnetic resonance imaging with fast and ultrafast sequences and postprocessing techniques (subtraction, time-intensity curves, and parametric color-encoding). In 10 of 40 patients, dynamic imaging more precisely defined the most malignant foci of tumor for biopsy than conventional magnetic resonance imaging. After chemotherapy, dynamic imaging distinguished 11 good responders from 21 poor responders. In followup of 196 patients, dynamic imaging detected 42 early enhancing recurrences and excluded recurrent tumor in six late enhancing pseudotumors. Dynamic imaging can differentiate viable tumor from nonviable tumor and inflammation by showing two temporally different phases of contrast enhancement: an early phase correlative with viable tumor at histologic examination, and a late phase when all tissues enhance simultaneously and may be indistinguishable. By showing tumor viability, dynamic contrast-enhanced magnetic resonance imaging can help define biopsy sites, chemotherapeutic response, and presence or absence of recurrences and therefore affect the initial evaluation, treatment, and followup of patients with soft tissue sarcomas.

Diffusion-weighted MRI in the characterization of soft-tissue tumors

PURPOSE

To explore the potential of perfusion-corrected diffusion-weighted magnetic resonance imaging (MRI) in characterizing soft-tissue tumors.

METHODS AND MATERIALS

Diffusion-weighted MRI was performed in 23 histologically proven soft-tissue masses using a diffusion-weighted spin-echo sequence with diffusion gradient strengths yielding five b-values (0-701 seconds/mm(2)). True diffusion coefficients and perfusion fractions were estimated and compared with apparent diffusion coefficients (ADCs).

RESULTS

ADC values of all tumors, subcutaneous fat, and muscle were significantly higher than true diffusion coefficients, indicating a contribution of perfusion to the ADC. True diffusion coefficients of malignant tumors (1.08 x 10(-3) mm(2)/second) were significantly lower than those of benign masses (1.71 x 10(-3) mm(2)/second), whereas ADC values between these groups were not significantly different.

CONCLUSION

Perfusion-corrected diffusion-weighted MRI has potential in differentiating benign from malignant soft-tissue masses.

Neurologic dysfunction in patients with rheumatoid arthritis of the cervical spine. Predictive value of clinical, radiographic and MR imaging parameters

The aim of this study was to evaluate if subjective symptoms, radiographic and especially MR parameters of cervical spine involvement, can predict neurologic dysfunction in patients with severe rheumatoid arthritis (RA). Sequential radiographs, MR imaging, and neurologic examination were performed yearly in 46 consecutive RA patients with symptoms indicative of cervical spine involvement. Radiographic parameters were erosions of the dens or intervertebral joints, disc-space narrowing, horizontal and vertical atlantoaxial subluxation, subluxations below C2, and the diameter of the spinal canal. The MR features evaluated were presence of dens and atlas erosion, brainstem compression, subarachnoid space encroachment, pannus around the dens, abnormal fat body caudal to the clivus, cervicomedullary angle, and distance of the dens to the line of McRae. Muscle weakness was associated with a tenfold increased risk of neurologic dysfunction. Radiographic parameters were not associated. On MR images atlas erosion and a decreased distance of the dens to the line of McRae showed a fivefold increased risk of neurologic dysfunction. Subarachnoid space encroachment was associated with a 12-fold increased risk. Rheumatoid arthritis patients with muscle weakness and subarachnoid space encroachment of the entire cervical spine have a highly increased risk of developing neurologic dysfunction.

Dynamic Contrast-Enhanced MR Imaging for Soft Tissue Sarcomas

Dynamic contrast-enhanced magnetic resonance imaging has recently emerged as an important method for evaluating soft tissue sarcomas for biopsy localization, chemotherapeutic response, and long-term follow-up because of its ability to detect viable tumor. This article presents the basic principles of contrast kinetics in soft tissue sarcomas after bolus injection of contrast agent and discusses the current postprocessing methods (subtraction, first-pass image and time-intensity curves with region of interest, and color-encoded techniques) used to display these dynamic studies. Because of its excellent temporal resolution, dynamic MR imaging can delineate the early uptake of contrast agent in sarcomas within seconds after injection, almost synchronous with arterial enhancement, and thereby differentiate the rapidly enhancing viable tumor from the nonenhancing necrotic tumor and the late enhancing changes after surgery, radiation therapy, and chemotherapy.