Contrast and nuclear arthrography in loosening of the uncemented hip prosthesis

The recent popularity of ingrowth or uncemented hip arthroplasties has presented problems in the radiographic diagnosis of loosening because there is no longer a cement interface in which lucencies may be seen. We evaluated a combination of positive contrast and nuclear arthrography to see whether these studies could accurately detect loosening of uncemented femoral components of hip prostheses. We performed routine contrast and nuclear arthrography in 21 patients with ingrowth total hip arthroplasties or bipolar endoprostheses. The results were surgically confirmed in 12 patients. The contrast arthrogram was true positive in 5 and false negative in 5. There were no false positives and 2 true negatives. The nuclear arthrogram was true positive in 7 patients, false negative in 3, and true negative in 2. Taken together, there was only 1 patient in whom both contrast and nuclear arthrography were false negative, and there were no false positives. Thus, when either contrast or nuclear arthrography is positive, the sensitivity of the combined procedures is 90%; when both studies are negative, the specificity is 100%. The combination of contrast and nuclear arthrography is an accurate method of determining loosening of the femoral component of an uncemented hip arthroplasty or bipolar endoprosthesis in the patient with postoperative hip pain.     

Imaging of low-grade bone infection with a technetium-99m labelled monoclonal anti-NCA-90 Fab' fragment in patients with previous joint surgery

Low-grade bone infection represents a serious clinical problem. Diagnostic options are often insufficient, yet the therapeutic implications of proven disease are important, especially in patients with prosthetic joint replacement. Technetium-99m labelled monoclonal anti-NCA-90 granulocyte antibody Fab' fragment (MN3 Fab') has been shown to be useful in bone and joint infection, but there are no data specifically referring to low-grade bone infection. We therefore analysed 38 scans in 30 consecutive patients (age range, 30-85 years; median age, 62 years) referred for suspected low-grade bone infection. There were 17 patients (21 scans) with total hip arthroplasty (THA), six with total knee arthroplasty (TKA), three who had undergone hip or knee surgery for trauma and five (seven scans) with resected hips and no endoprostheses (Girdlestone situations); one of these five patients had been investigated before with THA in situ and another prior to surgery for low-grade coxitis. There were no patients with rheumatoid arthritis as the underlying disease. Results were verified by means of bacteriological cultures, histopathological findings and/or follow-up and compared with the respective Zimmerli scores, which were used for clinical assessment of inflammatory activity. In one patient, the final diagnosis could not be established. One, 5 and 24 h after intravenous injection of up to 1.1 GBq of MN3 Fab', whole-body and planar scans were performed using a dual-head gamma camera. Scans were analysed visually and semiquantitatively adopting an arbitrary score ranging from 0 to 3. There were 13 true positive, 14 true negative and 10 false positive outcomes, yielding an overall sensitivity of 100%, an overall specificity of 58%, an accuracy of 73% and positive and negative predictive values of 57% and 100%, respectively. In patients with THA or TKA, accuracy was 81% and 80%, respectively, while it dropped to 43% in patients with Girdlestone situations owing to a high proportion of false positive findings (4/7) in this subgroup. Scintigraphic score was 1 in all of the false positive and in 11/13 true positive findings. The two remaining true positive findings displayed scintigraphic scores of 2 and 3, respectively. Scintigraphic and Zimmerli scores were loosely correlated (Spearman rho=0.38, P<0.05). Infection was excluded in 22/24 investigations with Zimmerli scores of <6. In this group, there were 13 scintigraphically true negative, nine false positive outcomes, and just two true positive outcomes. In 11/12 investigations with Zimmerli scores of 6 or 7, infection was verified and scintigraphic outcome was accordingly true positive, while the remaining patient was true negative. In conclusion, MN3 Fab' scintigraphy proved to be highly sensitive but not specific in diagnosing low-grade infections of the hip and knee regions in patients with previous joint surgery. The method seems reliable in excluding but not in proving the presence of infection. MN3 Fab' scintigraphy should not be applied in patients with Girdlestone situations. Assessment of infection using the Zimmerli score was more reliable than MN3 Fab' scintigraphy in this group of patients without rheumatoid arthritis as the underlying disease. Considering results from the literature concerning leucocyte scintigraphy, MN3 Fab' scintigraphy may be clinically useful in evaluating low-grade bone infection in THA and TKA patients with Zimmerli scores above 5 and concomitant rheumatoid arthritis or other inflammatory diseases.     

Arthrography of painful hips following arthroplasty: digital versus plain film subtraction

Digital and manual subtraction images obtained during the arthrographic evaluation of 78 painful hip prostheses were reviewed retrospectively. Revision arthroplasty was performed in 53 of these cases, and the arthrographic and surgical findings were correlated. The digital and manual subtraction images were evaluated without knowledge of the surgical results using established criteria for component loosening. Digital subtraction arthrography of the femoral component demonstrated a 96% sensitivity and 100% specificity for the diagnosis of component loosening. Sensitivity and specificity for acetabular component loosening were 83% and 80%, respectively. Plain film subtraction of the femoral component demonstrated a 79% sensitivity and 100% specificity; the sensitivity and specificity for the acetabular component were 75% and 80%, respectively. The difference between detection of femoral component loosening on digital as opposed to manual subtraction images was statistically significant (P<0.05). This study demonstrates that digital subtraction improves the evaluation of femoral component loosening in painful hip prostheses.     

The value of contrast arthrography in assessing loosening of symptomatic uncemented total hip components

Twenty-five patients with symptomatic uncemented total hip components were studied with contrast arthrography prior to surgical exploration. All but one had uncemented femoral stems and 16 had an uncemented acetabular component. As judged by the findings at surgery, on the femoral side the sensitivity, specificity, and accuracy of arthrography were 57%, 60%, and 58% respectively. There was a relatively high incidence of both false positives (17%) and false negatives (25%). On the acetabular side sensitivity, specificity, and accuracy were 29%, 89%, and 62.5%. False negatives were common (31%), while there was only one false positive. The results in this small series show that arthrography has distinct limitations in identifying the fixation status of uncemented total hip components.     

Clinical significance of axillary findings in patients with lymphoma during follow-up with 18F-fluorodeoxyglucose-PET

PURPOSE: The aim of this study was to evaluate the clinical significance of positive axillary findings in patients with Hodgkin's disease and non-Hodgkin's lymphoma during follow-up with 18F-fluorodeoxyglucose-PET. MATERIALS AND METHODS: We retrospectively reviewed PET scans carried out in 543 patients during follow-up. Patients with reports describing any increased fluorodeoxyglucose uptake at the axillary level were selected (106 cases) and final assessment of the findings was available in 78 patients (17 Hodgkin's disease, 51 non-Hodgkin's lymphoma). PET scans were performed after standard procedure and reports were interpreted as positive or negative on the basis of visual analysis. At the moment of the scan all patients had no clinical or laboratory sign of relapse, and had not received therapy for at least 6 months. All PET results were compared with other diagnostic procedures (ultrasonography and computed tomography), biopsy and/or follow-up data. RESULTS: Of 78 patients, 24 were PET positive in one axilla, 23 had axillary findings and one or more other extra axillary sites, five patients were positive in both axillas and 26 were positive in both axillas and one or more other sites. Of the 24 patients with single axillary finding, the result for five was true positive and for 19 it was false positive. Sixteen cases of the 23 patients with PET positive at one axilla and other sites had a true positive result, whereas seven had a false positive result. Only one of five patients with both axillas being positive at PET turned out to be true positive; finally, 23 cases from the 26 patients with both axillas and other findings had a true positive result and three of 26 had a false positive result. Overall, 45 out of 78 patients were true positive and 33 were false positive. CONCLUSION: Axillary findings are relatively frequent and can be isolated or in association with other findings. In patients with axillary involvement only the frequency of false positivity results is elevated and therefore these cases need to be evaluated carefully. In contrast, axillary findings associated with other pathological localizations show true positive results in most cases, thus indicating a high likelihood of disease recurrence. Standardized uptake values showed a limited role for discriminating true-positive and false-positive findings.     

Pancreatic cancer: preliminary experience with sodium iodide fluorodeoxyglucose positron emission tomography in Australia

Previous studies of fluorodeoxyglucose positron emission tomography (FDG-PET) in pancreatic cancer have used Bismuth Germinate detector systems. This preliminary Australian study aims to confirm the accuracy of FDG-PET in pancreatic cancer using a dedicated sodium iodide (NaI) PET system. Fifteen consecutive patients underwent FDG-PET using a GE QUEST dedicated NaI PET scanner. The indications were the characterization of a pancreatic mass seen on CT or ultrasonographic imaging (nine cases), diagnosis or exclusion of recurrent disease following surgery and adjuvant therapy (four cases) and presurgical staging of primary pancreatic cancer (two cases). The final diagnosis was determined from histology or, when no histology was available, by radiological and clinical follow up. The FDG-PET accurately characterized eight out of nine pancreatic masses (seven were true negative, one was true positive and one was false positive). Of the four cases performed to determine recurrent disease, three were accurately diagnosed (two true negatives and one true positive). In the fourth case, PET accurately detected a liver metastasis but did not detect the local recurrence. Results in the two cases where PET was performed for preoperative staging comprised one true positive and one false negative. Sodium iodide FDG-PET is useful in the diagnosis of pancreatic cancer, particularly in the presence of a previously detected mass.     

Recurrence of ovarian and uterine neoplasms: diagnosis with transrectal US

Twenty-one patients with clinically suspected recurrence of ovarian (n = 3) or uterine (n = 18) carcinoma were examined with suprapubic ultrasound (US) and transrectal US with high-frequency linear probes. The examinations were performed 3, 6, 9, and 15 months after surgery and radiation therapy. Eight patients underwent radiation therapy before surgery and ten after surgery; three underwent only surgery. Criteria for recurrence included increased anteroposterior diameter of the vaginal cuff (greater than 2.2 cm); structural alterations or presence of a mass in the vaginal cuff; and infiltration of the rectovaginal septum, bladder, and parametria. Transrectal US findings were true positive for recurrence in nine cases, true negative in ten, and false positive in two. US findings were true positive in three cases, true negative in seven, false positive in two, and false negative in three. In six cases results from US were technically poor, and no diagnosis could be made. Transrectal US was highly sensitive in detection of pelvic recurrent carcinomas, while US had little diagnostic value. The authors believe transrectal US can replace US in the evaluation of patients at risk for recurrent pelvic neoplasm.     

Small renal cell carcinomas: resolving a diagnostic dilemma

Thirty-nine patients with pathologically proved renal cell carcinomas 3 cm or les in diameter were examined. Results of intravenous urography (n = 30) were true positive in 20 patients and false negative in ten (sensitivity, 67%). Renal ultrasound (US) (n = 29) had true-positive results in 23 patients and false-negative results in six (sensitivity, 79%); computed tomography (CT) (n = 36) had true-positive results in 34 and false-negative results in two (sensitivity, 94%). For selective renal angiography (n = 35%), the results were true positive in 26 and false negative in nine (sensitivity, 74%), with typical hypervascular renal cell carcinomas demonstrated in 17. Finally, the findings of percutaneous fine-needle aspiration biopsy were true positive in one of five patients when US guidance was used (sensitivity, 20%) and in five of eight when CT guidance was used (sensitivity, 62%). Small renal cell carcinomas are more frequently encountered in clinical practice than heretofore realized, and they are best imaged by CT.     

The value of lymphography in the management of carcinoma of the cervix

Lymphography has been used to evaluate the pelvic and para-aortic nodes in 205 patients with carcinoma of the cervix treated between 1970 and 1979. The incidence of positive nodes was found to be 17% for Stage I, 24% for Stage II, 52% for Stage III and 100% for Stage IV. Of 73 patients who had lymphograms before Wertheim's hysterectomy, four out of 59 patients (7%) with negative lymphograms had histologically positive nodes; four out of 14 (28%) with positive lymphograms had negative nodes. Within each FIGO stage a positive lymphogram indicated a poor prognosis. The actuarial 5-year survival rates for patients with negative and positive lymphograms were 94% and 55% respectively for Stage I, 72% and 64% for Stage II, and 34% and 17% for Stage III. Of 39 patients with positive lymphograms who died of tumour, 31 out of 39 (80%) had distant metastases, compared with nine out of 29 patients (31%) with negative lymphograms. It is concluded that lymphography is a valuable method of evaluating lymph node status in carcinoma of the cervix.     

The use of [18 F]fluorodeoxyglucose positron emission tomography to differentiate between synovitis,loosening and infection of hip and knee prostheses

Pain is a common unspecific symptom in orthopaedic prosthetics. The accurate differentiation between synovitis, loosening or infection is often difficult with conventional X-rays, arthrography or bone scintigraphy. Because of the high glucose uptake of inflammatory cells, [18F]fluorodeoxyglucose (18F-FDG) is an appropriate tracer for the evaluation of suspected inflammation or infection. In this preliminary study we describe 18F-FDG PET findings in patients referred for evaluation of painful hip or knee prostheses. We studied 23 patients with 28 prostheses, 14 hip and 14 knee prostheses, who had a complete operative or clinical follow-up. 18F-FDG PET scans were obtained with an ECAT EXACT HR+ PET scanner. High glucose uptake in the bone prostheses interface was considered as positive for infection, an intermediate uptake as suspect for loosening, and uptake only in the synovia was considered as synovitis. The imaging results were compared with operative findings or clinical outcome. PET correctly identified three hip and one knee prostheses as infected, two hip and two knee prostheses as loosening, four hip and nine knee prostheses as synovitis, and two hip and one knee prostheses as unsuspected for loosening or infection. In three patients covered with an expander after explantation of an infected prosthesis PET revealed no further evidence of infection in concordance with the clinical follow-up. PET was false negative for loosening in one case. Our preliminary results suggest that FDG PET could be a useful tool for differentiating between infected and loose orthopaedic prostheses as well as for detecting only inflammatory tissue such as synovitis.     

Arthrographic study of painful total hip arthroplasty: refined criteria

The criteria for a diagnosis of loosening or infection of hip arthroplasties on arthrographic study were further refined by a retrospective review of 178 arthrograms representing 170 patients. The 97 arthroplasties that were surgically evaluated form the basis of this report. With the refined criteria, subtraction arthrography had a sensitivity of 96% and specificity of 92% for demonstrating loosening of the femoral component and a sensitivity of 97% and a specificity of 68% for demonstrating loosening of the acetabular component. Pseudocapsule size and the presence of bursae were important factors influencing arthrographic interpretation. Arthrographic findings of pseudocapsule irregularity and the presence of nonbursal cavities were suggestive of infection but were not sensitive or specific. Laboratory evaluation of aspirated material was a more reliable predictor of infection, although its sensitivity was only 71%.     

Correlation between radiologic and clinical findings in Charnley total hip replacement. A 10-year follow-up study

The main purpose of this study was to evaluate the relationship between the radiologic findings in clinically successful Charnley total hip replacements (THR) at an average of five years postoperatively ('5-year follow-up') and the clinical result 10 to 14 years after operation ('10-year follow-up'). The study included 150 arthroplasties graded as clinically successful at the 5-year follow-up despite radiologic loosening of the femoral component in 41 per cent and of the acetabular component in 7 per cent. The incidence of clinical failure between the two follow-ups was 7 per cent (10 hips). Only 2 per cent (3/125) of THRs with intact components or a loose stem with migration not exceeding 4 mm became failures. Clinical failures resulted in 28 per cent (7/25) of THRs with more extensive loosening of the stem or with a loose socket. At the 10-year follow-up 47 per cent of the femoral and 13 per cent of the acetabular components were loose. Progression of loosening of the femoral stem occurred in 63 per cent and of the socket in 73 per cent between the two follow-ups. The incidence of loosening of the stem showed a significant correlation both with the extent of cementation distal to the tip and with the orientation of the prosthesis in the sagittal plane.     

全涂层表面微孔股骨假体在人工全髋关节翻修术中的应用

目的评价全涂层股骨假体在人工髋关节翻修术后的X线表现和临床效果。方法自1999年1月至2003年12月，对15例患者15髋采用全涂层表面微孔股骨柄假体进行全髋关节翻修术。男6例，女9例；年龄58～82岁，平均66岁。翻修原因：无菌性假体松动10例，感染性松动2例，假体松动、股骨骨折2例，股骨假体位置不良1例。所有患者均采用Harris髋关节评分和手术前、术后定期X线评价。结果15例患者均获随访，随访时问1～5年，平均2．3年。术前平均Harris评分为42分，最后随访时增加至89分。所有患者均在术后3个月后完全负重，原有髋关节疼痛缓解。在最后随访时，有14例股骨柄假体获得骨长入固定，有1例获得稳定的纤维固定。并发症包括股骨干骨折2例，其中1例为股骨柄尖端处无移位骨裂，1例为股骨假体柄远端穿出股骨皮质，术后脱位1例。本组中无假体固定失败的患者。无一例患者发生感染。结论全涂层非骨水泥股骨假体是髋关节翻修股骨侧的良好选择，近期X线和临床效果满意，对个子矮小的患者选用加长翻修柄应慎重。     

Does dysbaric osteonecrosis progress in the absence of further hyperbaric exposure? A 10-year radiologic follow-up of 15 patients

Progression of dysbaric osteonecrosis of the femoral and humeral heads was evaluated in 15 caisson workers. All patients had dysbaric osteonecrosis but had had no further exposure to hyperbaric pressures for a minimum of 10 years. The original and follow-up radiographs were compared in each case. Of 24 normal articular heads (nine humeral and 15 femoral), one (4%) humeral head developed new subcortical sclerosis. Of the 36 juxta-articular lesions, seven (four humeral and three femoral) showed major changes in the 10-year interval. Of these seven, two (one humeral and one femoral) had new articular fractures and three (two humeral and one femoral) with articular fractures showed progressive osteoarthritis. We conclude that caisson workers can develop lesions in previously normal areas and experience worsening of previously known lesions in the absence of further exposure to hyperbaric pressures.     

Assessment of inflammatory bowel disease by using two different (99m)Tc leucocyte labelling methods

The aim of this study was to retrospectively compare the diagnostic accuracy of (99m)Tc hexamethylpropyleneamine oxime (HMPAO) white blood cell scintigraphy in patients with a suspicion of active inflammatory bowel disease by using two different cell suspension media: leukocyte poor plasma (LPP) and Hanks' balanced salt solution (HBSS). Leukocytes from 30 patients were labelled using LPP and in 28 cases using HBSS. In the LPP method the leukocytes were resuspended in 0.5 ml cell-free plasma while in the HBSS method the cells were resuspended in 0.5 ml HBSS. Scintigraphic images were obtained at 30 min and 2 h after injection of 185-200 MBq (99m)Tc-HMPAO leukocytes. The leukocyte labelling efficiency was 65.5% and 89.0%, respectively, for the LPP and HBSS methods. There were 22 true positive, seven true negative and one false negative result in the LPP group, while in the HBSS group results were 18, nine and one, respectively. Diagnostic accuracy was similar with both methods although sensitivity was slightly higher in the HBSS group. In summary, these date indicate that leukocyte scintigraphy labelling using HBSS as the resuspension medium should be used as a first option for white blood cell labelling and diagnosis of inflammatory bowel disease.     

Radiological evaluation of painful total hip replacement

Ninety-four cases of clinically failed, cemented, total hip prostheses requiring surgery were reviewed to determine the accuracy of preoperative plain radiography, culture of aspirated fluid, arthrography, and bone scanning. When radiopaque cement had been used to embed the prosthesis, plain radiography was highly accurate in detecting a loose femoral component, less so in detecting a loose acetabular component. Culture of aspirated fluid was accurate in diagnosing infection. A positive arthrogram identified loosening with good accuracy; however, a negative arthrogram did not reliably exclude loosening. 99mTc bone scans frequently differentiated loosening from loosening with infection. The suggested sequence of diagnostic tests is plain radiography followed by bone scanning. If the bone scan shows diffuse augmented uptake, culture of aspirated fluid followed by arthrography is indicated.     

Comparison of CT and three MR sequences for detecting and categorizing early (48 hours) hemorrhagic transformation in hyperacute ischemic stroke

BACKGROUND AND PURPOSE: Our goal was to compare the sensitivity of CT and three MR sequences in detecting and categorizing early (48 hours) hemorrhagic transformation (HT) in hyperacute ischemic stroke. METHODS: Twenty-five consecutive patients with hyperacute ischemic stroke (<6 hours) without MR signs of cerebral bleeding at admission were included. Twenty-one underwent thrombolytic therapy. A standardized follow-up protocol, performed 48 hours after admission, combined brain CT scan and MR examination (1.5 T) including fast spin-echo-fluid-attenuated inversion recovery (FSE-FLAIR), echo-planar spin-echo (EPI-SE) T2-weighted, and EPI-gradient-recalled echo (GRE) T2*-weighted sequences. Both CT scans and MR images were obtained within as short a time span as possible between techniques (mean delay, 64 minutes). CT scans and MR images were independently rated as negative or positive for bleeding and categorized for bleeding severity (five classes) by two blinded observers. Prevalence of positive cases, intra- and interobserver agreement, and shifts in bleeding categorization between respective modalities and sequences were assessed. RESULTS: Twelve patients (48%) were rated positive for HT on the basis of findings of at least one technique or sequence. From this subset of bleeding patients, seven (58%) had positive CT findings, nine (75%) had positive FSE-FLAIR and EPI-SE T2-weighted findings, and 12 (100%) had positive EPI-GRE T2*-weighted findings. CT had lower intra- and interobserver agreement for positivity than did MR imaging. Among the seven patients with positive CT and MR findings, only two had convergent ratings for bleeding category based on findings of two modalities. The five remaining had upward grading from CT to MR, which varied according to pulse sequence. CONCLUSION: MR imaging depicted more hemorrhages and had higher intra- and interobserver agreement than did CT. The EPI-GRE T2*-weighted sequence demonstrated highest sensitivity. Equivocal upward shifts in bleeding categorization were observed from CT to MR imaging and between MR images.     

Direct comparison of FDG PET and CT findings in patients with lymphoma: initial experience

PURPOSE: To retrospectively compare fluorine 18 fluorodeoxyglucose (FDG) positron emission tomographic (PET) and computed tomographic (CT) findings at the same anatomic locations in patients with lymphoma by using a combined PET/CT scanner and to analyze the lesions on metabolic and anatomic bases to evaluate causes of discrepant findings between the two modalities. MATERIALS AND METHODS: The institutional review board allowed an exempt retrospective review of cancer PET database, and informed consent was waived. The study was HIPAA compliant. Fifty-three patients with lymphoma (20 Hodgkin and 33 non-Hodgkin; mean age, 43 years; range, 12-83 years) who underwent FDG PET/CT were included. The PET and CT images were interpreted by two nuclear medicine physicians and one radiologist, respectively, blinded to the other imaging findings. Concordant PET and CT findings were regarded as positive or negative for lymphoma. The site with discordant findings was defined as positive for disease if it was accompanied by other PET- and CT-positive sites in the same patient or was confirmed clinically (histologic examination or progressive disease). Staging results were also compared by one nuclear medicine physician. RESULTS: Of a total of 1537 anatomic sites in 53 patients, 48 had discordant findings between PET and CT. Forty (83%) of the 48 sites had correct PET findings (31 positive, nine negative), five had correct CT findings, and three were unresolved. The 31 PET-positive and CT-negative sites accounted for 23% of all 134 true-positive PET sites. PET provided accurate staging in an incremental nine (17%, upstaging in four and downstaging in five) of 53 patients in whom CT staging was incorrect. CT provided correct upstaging in two patients. CONCLUSION: FDG PET/CT as a combined modality may contribute substantially to lesion characterization and staging in patients with lymphoma.     

Multidetector CT in diagnostic work-up of patients with primary hyperparathyroidism

PURPOSE: This study was performed to evaluate the accuracy of multidetector computed tomography (MDCT) in detecting parathyroid lesions in patients with primary hyperparathyroidism. MATERIALS AND METHODS: We included 60 patients with primary hyperparathyroidism. Preoperative first-line examinations revealed negative and doubtful ultrasound (US) findings in 34 and 26 cases, respectively, and negative, doubtful and positive scintigraphic findings in 19, 20 and 21 cases, respectively. CT findings were compared with the surgical results. RESULTS: CT examination was positive in 35 cases, negative in 15 cases and doubtful in ten cases. Forty out of 60 patients underwent surgery, and 39 lesions (37 adenomas, two primary hyperplasias) were identified. Surgery was negative in two cases. In eight cases, lesions had ectopic location. Surgery confirmed the CT findings in 23 positive cases. In 8/10 doubtful cases, surgery confirmed the location of the lesion in five cases, identified the ectopic location of lesions in two cases, and was negative in one case. In 9/15 cases with negative CT findings, surgery identified the lesion in eight cases. Sensitivity, specificity and diagnostic accuracy values were 78%, 25% and 73%, respectively. CONCLUSIONS: MDCT is an accurate second-line diagnostic technique in the detection of parathyroid lesions, allowing exploration of the entire cervical and mediastinal regions.     

131I-meta-iodobenzylguanidine scintigraphy in patients with a suspected pheochromocytoma. A comparison with CT and biohumoral parameters]

The results of 131I metaiodobenzylguanidine (MIBG) and Computed Tomography (CT) scans in a group of patients with clinically suspected pheochromocytoma were evaluated and compared with biohumoral parameters. We studied 24 consecutive patients (7 M and 17 F; age range 20-66 years). 131I-MIBG scintigraphy and CT were in agreement in 19 patients (79%): of them 7 cases were true positive, and 12 were true negative. Disagreement between the two imaging techniques was observed in 5 patients (21%). In this group, one patient, with positive CT scan, had false negative MIBG study, while 4 patients with negative MIBG scan, had false positive CT. MIBG showed significantly higher (p less than 0.05) specificity (100%), positive predictive value (100%), and accuracy (96%) than CT (75%, 67%, and 83%, respectively). 131I-MIBG scintigraphy is an accurate, noninvasive technique for localizing pheochromocytoma and providing direct tissue characterization, while CT provides more accurate spatial information. In conclusion, CT and MIBG studies are complementary in the evaluation of patients with suspected pheochromocytoma.