Usefulness of CT scan, MRI and radiocholesterol scintigraphy for adrenal imaging in Cushing's syndrome

The aim of this study was to evaluate the sensitivity and accuracy of computed tomography (CT) scanning, 75Se-selenomethyl-norcholesterol scintigraphy (SNS) and magnetic resonance imaging (MRI) in patients with Cushing's syndrome (CS) undergoing adrenalectomy. A series of 67 patients with CS due to benign adrenal disease was reviewed. There were 11 (16.4%) men and 56 (83.6%) women, with an overall median age of 44 years (range 19-69 years). Prior to surgery all patients underwent both CT and SNS, and 58 (86.6%) underwent adrenal MRI. Thirty-five (52.2%) of the patients (group A) had histologically confirmed unilateral adrenal involvement (33 patients with a solitary adrenocortical adenoma, and two with unilateral nodular cortical hyperplasia), while 32 (47.8%) of the patients (group B) had CS caused by bilateral adrenal involvement, including two patients with multinodular adrenal hyperplasia. The sensitivity, specificity and accuracy of adrenal imaging in group A were 97.1%, 100% and 98.5% for SNS, 94.3%, 68.7% (P<0.05, chi2 test) and 82.1% for CT scan, and 92.3%, 60.0% (P<0.05) and 64.3% (P<0.05) for MRI, respectively. In group B the sensitivity, specificity and accuracy were 100%, 97.2% and 98.5% for SNS, 64.5% (P<0.05), 97.2% and 82.1% for CT scan, and 60.0% (P<0.05), 92.3% and 35.7% (P<0.05) for MRI, respectively. In conclusion, SNS represents the most sensitive and specific adrenal imaging study and should be used in all patients with confirmed biochemical diagnosis of CS undergoing adrenalectomy. The sensitivity and specificity of CT scan and MRI are similar, but the latter shows a lower accuracy, especially in patients with bilateral adrenal involvement.     

The diagnostic role of radionuclide imaging in evaluation of patients with nonhypersecreting adrenal masses.

The aim of this study was to evaluate the role of radionuclide imaging in the characterization of nonhypersecreting adrenal masses. METHODS: A total of 54 patients (19 men, 35 women; mean age, 50 +/- 16 y) with nonhypersecreting unilateral adrenal tumors that had been originally detected on CT or MRI underwent adrenal scintigraphy using different radiotracers. None of the patients showed specific symptoms of adrenal hypersecretion. Screening tests for excess cortical and medullary products showed normal adrenal hormone levels. Radionuclide studies (n = 73) included (131)I-norcholesterol (n = 24), (131)I-metaiodobenzylguanidine (MIBG) (n = 23), and (18)F-FDG PET (n = 26) scans. RESULTS: Histology after surgery (n = 31) or adrenal biopsy (n = 23) was obtained. Adrenal lesions were represented by 19 adenomas, 4 cysts, 1 myelolipoma, 1 neurinoma, 2 ganglioneuromas, 5 pheochromocytomas, 4 pseudotumors, 6 carcinomas, 2 sarcomas, and 10 metastases (size range, 1.5- to 5-cm diameter; mean, 4.9 +/- 3.1 cm). For norcholesterol imaging, diagnostic sensitivity, specificity, and accuracy were 100%, 71%, and 92%, respectively; the positive predictive value (PPV) of the norcholesterol scan to characterize an adrenal mass as an adenoma was 89%, whereas the corresponding negative predictive value (NPV) to rule out this type of tumor was 100%. For MIBG imaging, diagnostic sensitivity, specificity, and accuracy were 100%, 94%, and 96%, respectively; the PPV of the MIBG scan to characterize an adrenal mass as a medullary chromaffin tissue tumor was 83%, whereas the corresponding NPV to rule out this type of tumor was 100%. For FDG PET, diagnostic sensitivity, specificity, and accuracy were 100%, 100%, and 100%, respectively; the PPV of FDG PET to characterize an adrenal mass as a malignant tumor was 100%, whereas the corresponding NPV to rule it out was 100%. Furthermore, in 7 patients with malignant adrenal tumors, FDG whole-body scanning revealed extra-adrenal tumor sites (n = 29), allowing an accurate diagnosis of the disease's stage using a single-imaging technique. CONCLUSION: In patients with nonhypersecreting adrenal masses, radionuclide adrenal imaging, using specific radiopharmaceuticals such as norcholesterol, MIBG, and FDG, may provide significant functional information for tissue characterization. Norcholesterol and MIBG scans are able to detect benign tumors such as adenoma and pheochromocytoma, respectively. Conversely, FDG PET allows for recognition of malignant adrenal lesions. Therefore, adrenal scintigraphy is recommended for tumor diagnosis and, hence, for appropriate treatment planning, particularly when CT or MRI findings are inconclusive for lesion characterization.     

Diagnostic performance of CT versus MR in detecting aldosterone-producing adenoma in primary hyperaldosteronism (Conn’s syndrome)

The aim of the present study is to compare the diagnostic performance of CT and MR imaging in detecting aldosterone-producing adenoma and to compare the interobserver variability in the detection of an aldosterone-producing adenoma on CT and MR. A retrospective study of 34 patients with primary hyperaldosteronism was performed. A total of 17 cases of aldosterone-producing adenoma and 17 cases of bilateral adrenal hyperplasia were included. The final diagnosis of an adenoma was made by surgery with histological confirmation, whereas that of bilateral adrenal hyperplasia was made on adrenal venous sampling or a good biochemical and clinical response following medical treatment alone and in the absence of a unilateral radiological abnormality. The CT (n=30) and MR (n=24) scans were reviewed independently by two radiologists experienced in adrenal imaging, who were unaware of the cause of the primary hyperaldosteronism. The diagnostic performances of both observers in detecting an aldosterone-producing adenoma on CT and MR imaging were compared. The 16 adenomatous nodules that were detected on imaging ranged from 1 to 4.75 cm in diameter. The calculated sensitivity and specificity for detecting aldosterone-producing adenoma were 87 and 93% for one observer and 85 and 82% for the other observer on CT, and 83 and 83% for one observer and 92 and 92% for the other observer on MR, respectively. Receptor operating characteristics curve analysis showed similar performances of both observers in detecting an aldosterone-producing adenoma on CT and MR imaging. There was good interobserver agreement on CT (k=0.71) and on MR (k=0.67). We have demonstrated comparable diagnostic performance and good interobserver agreement on CT and MR imaging for the detection of aldosterone-producing adenoma.     

12. Patterns of Adrenal Gland Involvement from Lung Cancer Shown by 18F-Fluorodeoxyglucose Positron Emission Tomography Compared to Computed Tomography and Magnetic Resonance Imaging

Purpose: The frequency of adrenal metastases from non-small cell lung cancer (NSCLC) varies between 4 to 25%. Adrenal metastases are frequently missed (78%) by Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). The purpose of this study was to characterize the patterns of adrenal gland involvement from lung cancer by 18-F-Fluorodeoxyglucose Positron Emission Tomography (18FDG-PET).Methods: Retrospective review of patients evaluated for known or suspected lung carcinoma. Results of 18FDG-PET, CT, MRI, and scans were compared.Results: From February 1996 to May 2000, 91 patients with known (85 patients) or suspected (6 patients) lung cancer were evaluated with 18FDG-PET scan. Twenty-two patients (mean age 63, range 38-88 years) had abnormal adrenal glands by either 18FDG-PET (16 patients), CT (12 patients) or MRI (1 patient). In 13 cases 18FDG-PET scan was ordered to clarify CT or MRI findings. Only 7 patients showed adrenal gland involvement: 5 patients (5.5%) with unilateral disease and 2 patients (2.2%) with bilateral disease. PET depicted unsuspected findings in 9 patients: 8 patients (8.8%) with unilateral disease and 1 patient (1.1%) with bilateral disease.(18)FDG-PET upstaged 9 patients from limited (N1M0) to widespread disease (M1), thus obviating surgical intervention.Conclusion: This study demonstrates the potential of 18FDG-PET scanning in revealing unsuspected adrenal metastases in patients with early stages of NSCLC as well as characterizing CT or MRI equivocal adrenal masses.     

Prospective evaluation of nonenhanced MR imaging in acute pancreatitis

PURPOSE: To compare the value of nonenhanced (NE) magnetic resonance imaging (MRI) (NE-MRI) with contrast-enhanced (CE) computed tomography (CT) (CE-CT) scan in assessing acute pancreatitis (AP) and in evaluating the severity index (SI) with clinical outcome. MATERIALS AND METHODS: Patients with AP were prospectively investigated by CE-CT scan and NE-MRI on admission. MRI was performed with fat-saturated T1-weighted imaging, T2-weighted imaging, and MR cholangiopancreatography (MRCP). Balthazar's grading system was used to evaluate the NE-MRI severity index (CTSI, MRISI) and it was compared to the clinical outcome. RESULTS: A total of 90 patients (median age = 55 years) were included in the study. AP was of biliary etiology in 37 patients (41%). On admission, AP was assessed as grade III by CTSI in four patients (4%), whereas 19 patients were classified grade III by MRISI. The coefficient correlation between CTSI and MRISI was good, with r = 0.6 (P < 0.001). Considering CE-CT scan as the gold standard, sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of NE-MRI for detecting severe AP based on imaging criteria were 100%, 82.6%, 100%, and 21%, respectively. NE-MRI discriminates normal pancreatic parenchyma from edema and necrosis with a correlation between morbidity (P < 0.008). CONCLUSION: NE-MRI seems to be a reliable method of staging AP severity in comparison to CE-CT scan.     

CT of primary hyperaldosteronism (Conn's syndrome): the value of measuring the adrenal gland

OBJECTIVE: The objectives of our study of patients with primary hyperaldosteronism (Conn's syndrome) were to determine whether the adrenal glands are larger in patients with bilateral adrenal hyperplasia than in those with aldosterone-producing adenomas or in healthy control subjects; and whether a CT criterion based on adrenal gland size can be developed to positively diagnose bilateral adrenal hyperplasia. MATERIALS AND METHODS: A retrospective study of CT scans of 28 patients with primary hyperaldosteronism was performed. The means of two observers' measurements of adrenal gland size were recorded and compared with published normal values. In addition, a radiologist experienced in adrenal imaging and unaware of the cause of the primary hyperaldosteronism diagnosed either bilateral adrenal hyperplasia or aldosterone-producing adenoma by visual inspection. RESULTS: The adrenal glands in patients with bilateral adrenal hyperplasia were significantly (p < 0.05) larger than those in patients with aldosterone-producing adenoma or in healthy control subjects. A sensitivity of 100% was achieved when a mean limb width of greater than 3 mm was used to diagnose bilateral adrenal hyperplasia, and a specificity of 100% was achieved when the mean limb width was 5 mm or greater. Receiver operating characteristic curve analysis showed that the overall performance of the radiologist and the mean adrenal limb width in detecting bilateral adrenal hyperplasia were equivalent. CONCLUSION: In patients with primary hyperaldosteronism, adrenal limb measurements on CT can aid in differentiating bilateral adrenal hyperplasia from aldosterone-producing adenoma because the adrenal glands in bilateral adrenal hyperplasia are larger.     

Value of 2-[18F]-fluoro-2-deoxy-D-glucose imaging with dual-head gamma camera in coincidence mode: comparison with computed tomography/magnetic resonance imaging in patients with suspected recurrent head and neck cancers

OBJECTIVE: The aim of the present study was to assess the value of dual-head gamma-camera (DHGC) imaging in the coincidence mode using 2-[18F]-fluoro-2-deoxy-D-glucose in differentiating recurrent tumor from posttreatment changes in previously treated head and neck cancer. METHODS: This was a single-center prospective study performed with the approval of our Institutional Review Board. Twenty-nine patients with suspected recurrent head and neck cancers were prospectively enrolled in this study. Dual-head gamma-camera imaging in the coincidence mode followed computed tomography (CT; n = 24)/magnetic resonance imaging (MRI; n = 5) within a period of 1 week (mean = 3.5 days) in all patients. Thirteen patients had definite pathologic confirmation of recurrence by undergoing a biopsy. Sixteen patients, however, did not have a definite pathologic confirmation and were followed clinically. The mean duration of follow-up for the subgroup of patients who were followed clinically was 22.8 months (range: 4-48 months). Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for CT/MRI and DHGC imaging in the coincidence mode were calculated. RESULTS: The sensitivity, specificity, PPV, NPV, and accuracy of CT/MRI in the detection of recurrent cancer were 76.5%, 58.3%, 72.2%, 63.6%, and 69%, respectively. In contrast, the sensitivity (100%), NPV (100%), and accuracy (82.8%) of DHGC imaging in the coincidence mode were superior to that of CT/MRI. Dual-head gamma-camera imaging in the coincidence mode had a specificity (58.3%) and PPV (77.3%) comparable to those of CT/MRI. CONCLUSION: Our data suggest that modified positron emission tomography with DHGC imaging in the coincidence mode is a useful tool in the assessment of recurrent head and neck cancer.     

Improving liver lesion characterisation using retrospective fusion of FDG PET/CT and MRI

AimTo compare retrospectively fused FDG PET/CT and MRI (PET/MRI) to FDG PET/CT and MRI for characterisation of indeterminate focal liver lesions as malignant or benign in patients with a known primary malignancy.Materials and methodA retrospective review of 70 patients (30 females, 40 males; mean age 56 ± 14 years) with 150 indeterminate lesions after FDG PET/CT and MRI (mean scan time interval 21 ± 11 days). HERMES® software was used to fuse PET/CT and MRI scans which were reviewed by 2 readers using the Likert score (scale 1–5) to characterise lesions as benign (1–3) or malignant (4–5). Final diagnosis was determined by histopathology or follow up imaging. Results for fused PET/MRI were compared to PET/CT and MRI alone.ResultsFor detection, MRI and fused PET/MRI detected all the lesions while PET/CT detected 89.4%. Characterisation of liver lesions as malignant on PET/CT alone yielded sensitivity, specificity, accuracy, PPV and NPV of 55.6%, 83.3%, 66.7%, 83.3%, 55.6% respectively and 67.6%, 92.1%, 80%, 89.3%, 74.5% for MRI, respectively. The sensitivity, specificity, accuracy, PPV and NPV for characterising lesions as malignant increased to 91.9%, 97.4%, 94.7%, 97.1%, 92.5% with PET/MRI fusion. The sensitivity, specificity, accuracy, PPV and NPV of fused PET/MRI for characterising lesions as malignant remained superior to PET/CT and MRI.ConclusionRetrospective fusion of PET with MRI has improved characterisation of indeterminate focal liver lesions compared to MRI or FDG PET/CT alone.     

Comparison between multislice CT and MR imaging in the diagnostic evaluation of patients with pancreatic masses

Purpose

This study compared the results of multislice computed tomography (MSCT) and high-field magnetic resonance imaging (MRI) in the diagnostic evaluation of pancreatic masses.

Materials and methods

Forty patients with clinical and ultrasonographic evidence of pancreatic masses underwent MSCT and MRI. The majority of patients (31/40, 78%) had proven malignant pancreatic tumours (24 ductal adenocarcinoma, six mucinous cystadenocarcinoma, one intraductal papillary mucinous carcinoma), whereas the remaining patients (9/40, 22%) were found to have benign lesions (eight chronic pancreatitis, one serous cystadenoma). Results of the imaging studies were compared with biopsy (n=33) and/or histology (n=7) findings to calculate sensitivity, specificity, accuracy and positive (PPV) and negative (NPV) predictive value for correct identification of tumours and evaluation of resectability of malignancies.

Results

Both for tumour identification and resectability, MSCT and MRI had comparable diagnostic accuracy, with no statistically significant differences between them. Tumour identification CT/MRI: accuracy 98/98%, sensitivity 100/100%, specificity 88/88%, PPV 97/97%, NPV 100/100%; tumour resectability CT/MRI: accuracy 94/90%, sensitivity 92/88%, specificity 100/100%, PPV 100/100%, NPV 78/70%.

Conclusions

MRI represents a valid diagnostic alternative to CT in the evaluation of patients with pancreatic masses, both for correct identification and characterisation of primary lesions and to establish resectability in the case of malignancies. New high-field MRI equipment allows optimal imaging quality with good contrast resolution in evaluating the upper abdomen.     

鞍区毛细胞型星形细胞瘤CT和MRI表现及误诊分析

目的探讨鞍区毛细胞型星形细胞瘤的CT和MR I表现并分析误诊原因。资料与方法回顾性分析12例经病理证实的鞍区毛细胞型星形细胞瘤的影像学表现。11例行头颅MR I平扫及增强扫描,其中4例同时行头颅CT平扫及增强扫描;另有1例仅行头颅CT平扫及增强扫描。结果 12例中囊实性7例,实性5例。8例肿瘤边界不清,4例边界清晰。MR T2W I呈混杂或均匀高信号,T1W I呈等低信号;CT表现为不均匀高密度或等密度;增强扫描多表现为明显不均匀强化。7例视交叉显示不清,3例垂体柄显示不清。术前影像学诊断错误8例,误诊为颅咽管瘤(n=6)、脑膜瘤(n=1)、生殖细胞瘤(n=1),另有2例未做出明确诊断。结论鞍区毛细胞型星形细胞瘤多为囊实性或实性且有类似Ⅲ~Ⅳ级胶质瘤影像表现的特点,可根据这些特点与其他鞍区肿瘤相鉴别,减少误诊。     

Adrenal venous sampling for stratifying patients for surgery of adrenal nodules detected using dynamic contrast enhanced CT

PURPOSE

We aimed to assess the value of adrenal venous sampling (AVS) for diagnosing primary aldosteronism (PA) subtypes in patients with a unilateral nodule detected on adrenal computed tomography (CT) and scheduled for adrenalectomy.

MATERIALS AND METHODS

This retrospective study included 80 consecutive patients with PA undergoing CT and AVS. Different lateralization indices were assessed, and a cutoff established using receiver operating characteristic curve analysis. The value of CT alone versus CT with AVS for differentiating PA subtypes was compared. The adrenalectomy outcome was assessed, and predictors of cure were determined using univariate analysis.

RESULTS

AVS was successful in 68 patients. A cortisol-corrected aldosterone affected-to-unaffected ratio cutoff of 2.0 and affected-to-inferior vena cava ratio cutoff of 1.4 were the best lateralization indices, with accuracies of 82.5% and 80.4%, respectively. CT and AVS diagnosed 38 patients with aldosterone-producing adenomas, five patients with unilateral adrenal hyperplasia, and 25 patients with bilateral adrenal hyperplasia. Of the 52 patients with a nodule detected on CT, subsequent AVS diagnosed bilateral adrenal hyperplasia in 14 patients (27%). Compared to the results of combining CT with AVS, the accuracy of CT alone for diagnosing aldosterone-producing adenomas was 71.1% (P < 0.001). The cure rate for hypertension after adrenalectomy was 39.2%, with improvement in 53.5% of patients. On univariate analysis, predictors of persistent hypertension were male gender and preoperative systolic blood pressure.

CONCLUSION

To avoid inappropriate surgery, AVS is necessary for diagnosing unilateral nodules with aldosterone hypersecretion detected by CT.Primary aldosteronism (PA) is the most common form of secondary hypertension, with a prevalence of 5%–11% (1–3). PA is due primarily to the hypersecretion of aldosterone by an aldosterone-producing adenoma (APA) or unilateral (primary) adrenal hyperplasia (UAH), which constitute 30%–40% of cases; the remainder are presumed to be secondary to idiopathic bilateral adrenal hyperplasia (BAH) (1, 4, 5). APA and UAH are two forms of unilateral aldosterone hypersecretion, and both are curable with adrenalectomy. BAH induces bilateral aldosterone hypersecretion, and anti-aldosterone drugs are used in its medical management (5–7).The plasma aldosterone-to-renin ratio is used to screen for PA in patients at high risk for PA (8). Recent guidelines recommend using computed tomography (CT) of the adrenal gland to categorize the subtype after confirming PA. However, CT cannot reliably visualize a microadenoma or distinguish between an incidentaloma or BAH and APA. It has been suggested that adrenal venous sampling (AVS) be performed to determine the subtype of PA and to differentiate between unilateral and bilateral production of aldosterone preoperatively (9). AVS to measure the adrenal vein aldosterone and cortisol is the gold standard for lateralizing aldosterone secretion (10). Lateralization is defined using several ratios. In patients with APA or UAH, a unilateral adrenalectomy results in a complete cure or improved hypertension and potassium normalization in approximately 30% of patients, with reported rates up to 86% (11–15).This study assessed several lateralization ratios to establish the most predictive of unilateral disease. We also compared the CT results with those of bilateral AVS for differentiating the PA subtype, with the assumption that AVS is necessary before surgery, even in patients with nodules <10 mm detected with CT. Finally, we assessed the outcomes of adrenalectomy in our patients to identify preoperative predictors of a good outcome.     

肾上腺恶性肿瘤的CT、MRI表现及其病理基础

目的：分析肾上腺恶性肿瘤(MAT)的 CT 和 MRI 表现,提高对本病的认识和影像诊断水平。方法收集、分析经临床病理证实的17例 MAT 的 CT、MRI 表现。CT 平扫17例,其中增强扫描14例;MRI 平扫3例,其中增强扫描2例;3例同时进行CT 和 MRI 扫描。结果肾上腺原发性恶性肿瘤8例,其中肾上腺皮质腺癌3例,神经母细胞瘤2例,恶性嗜铬细胞瘤、淋巴瘤、平滑肌肉瘤各1例;肾上腺转移瘤9例。肾上腺恶性肿瘤的平扫表现(肿块形态、大小、边缘、密度及信号)、增强(强化程度、方式)等特征有助于其诊断与鉴别诊断。结论部分 MAT 具有一定特征性的 CT、MRI 表现,结合相关临床资料,可在术前做出正确诊断。     

111In-octreotide is superior to 123I-metaiodobenzylguanidine for scintigraphic detection of head and neck paragangliomas.

In this study, we evaluated the diagnostic yield of somatostatin receptor scintigraphy (SRS), I-metaiodobenzylguanidine (MIBG) scintigraphy, and morphologic imaging (CT or MRI) in patients with head and neck paragangliomas. METHODS: In a university hospital setting, patients considered to have head and neck paraganglioma were referred to the outpatient endocrinology department and underwent CT or MRI, SRS, and MIBG imaging. For validation, we used a composite reference standard consisting of clinical and histologic data and CT or MRI, with which SRS and MIBG imaging were compared. Urinary metanephrine and normetanephrine measurements were also obtained. RESULTS: Twenty-nine consecutively referred patients (17 women and 12 men) were included and were found to have paraganglioma. Both morphologic and SRS were positive in 27 patients (sensitivity, 93%, and 95% confidence interval [CI], 77%-98%, compared with the composite reference standard), whereas MIBG was positive in only 13 patients (44%; 95% CI, 23%-61%) (P < 0.001, compared with SRS). On a lesion-based analysis, morphologic imaging detected 31 lesions (sensitivity, 82%; 95% CI, 65%-92%), SRS detected 34 (89%; 95% CI, 75%-97%), and MIBG detected 15 (42%; 95% CI, 26%-59%). SRS was superior to MIBG (P = 0.001). With SRS, a previously unknown carcinoid tumor was detected in 1 patient, and a carcinoid was suspected in another patient. MIBG detected an additional adrenal pheochromocytoma in 1 patient. Urinary metanephrine or normetanephrine excretion was elevated in 6 patients. The number of lesions on SRS and MIBG per patient correlated with the levels of abnormal metanephrine or normetanephrine excretion (P = 0.005 and P = 0.02, respectively). CONCLUSION: SRS was superior to MIBG in patients with highly suspected head and neck paraganglioma.     

CT在原发性醛固酮增多症患者肾上腺结节鉴别诊断中的价值

目的 探讨CT在鉴别诊断原发性醛固酮增多症患者肾上腺结节性质中的价值.资料与方法 回顾性分析184例经手术病理证实的原发性醛固酮增多症患者共190个肾上腺结节的CT表现及非载瘤肾上腺体部及侧肢厚度,比较醛固酮腺瘤与肾上腺增生结节的CT征象的发生率.结果 醛固酮腺瘤组与肾上腺增生结节组患者性别(P=0.040)、最大径(P=0.000)和边缘环形强化发生率(P=0.000)差异有统计学意义,但两组患者年龄(P=0.957)、结节数目(P=0.607)、侧别(P=0.667)、位置(P=0.612)、平扫CT值(P=0.835)以及3min绝对廓清率(P=0.057)、5min绝对廓清率(P=0.679)和7min绝对廓清率(P=0.512)差异无统计学意义.结论 原发性醛同酮增多症患者肾上腺腺瘤与增生结节在CT表现上存在很多重叠,但结节大小和边缘有无环形强化在鉴别腺瘤与增生结节中有重要意义.     

Diagnostic accuracy of chemical-shift MR imaging to differentiate between adrenal adenomas and non adenoma adrenal lesions

PURPOSE: The objective of this study was to evaluate the diagnostic accuracy of chemical-shift (CS) magnetic resonance (MR) imaging in the differential diagnosis of adenoma and nonadenoma adrenal masses. MATERIALS AND METHODS: We enrolled 36 patients (9 men, 27 women, mean age 51.3+14.4 years) with unilateral (n=31) or bilateral (n=5) adrenal masses incidentally discovered during imaging examinations [ultrasound (US), computed tomography (CT)] performed for other indications. A total of 41 adrenal lesions were evaluated (mean diameter 3.0+2.2 cm). Histology (n=19), biopsy (n=3) or clinical-imaging follow-up (n=19) demonstrated 29 adenomas, five pheochromocytomas, three cysts and four carcinomas. MR imaging was performed using the following breath-hold sequences: T1-fast field echo (FFE) [repetition time (TR)/echo time (TE)=236/4.6 ms], T2-turbo spin echo-single shot (TSE-SSh) (TR/TE=831/80 ms), T1-DUAL-FFE (TR=236, double TE=4.6/2.3 ms in phase and out of phase) and T1-FFE after gadolinium-DTPA (Gd). Axial and coronal imaging planes were used, with a slice thickness of 3-5 mm. MR images were qualitatively assessed for signal intensity of the adrenal mass relative to the liver on T1, T2, CS and T1-Gd scans; diagnostic criteria for adenomas were isointensity or hypointensity on both T1 and T2 scans, out-of-phase CS signal loss and mild transient enhancement after Gd. RESULTS: Analysis of T1-T2 signal intensity showed diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 80%, 72%, 100%, 100% and 60%, respectively. In contrast, analysis of CS and T1-Gd signal intensity showed diagnostic accuracy, sensitivity, specificity, PPV and NPV for both sequences of 93%, 90% (p<0.05 vs. T1-T2 analysis), 100%, 100% and 80% (p<0.05 vs. T1-T2 analysis), respectively. CONCLUSIONS: CS MR imaging significantly improves characterization of adrenal masses compared with conventional T1-T2-weighted images, providing accuracy similar to that of the T1 sequence after Gd. Therefore, the CS sequence is strongly recommended for MR study of adrenal masses, and its use might obviate the need for Gd administration.     

Quantitative evaluation of norcholesterol scintigraphy, CT attenuation value, and chemical-shift MR imaging for characterizing adrenal adenomas

OBJECTIVE: The objective of our study was to evaluate diagnostic ability and features of quantitative indices of three modalities: uptake rate on norcholesterol scintigraphy, computed tomography (CT) attenuation value, and fat suppression on chemical-shift magnetic resonance imaging (MRI) for characterizing adrenal adenomas. METHODS: Image findings of norcholesterol scintigraphy, CT, and MRI were reviewed for 78 patients with functioning (n = 48) or nonfunctioning (n = 30) adrenal masses. The norcholesterol uptake rate, attenuation value on unenhanced CT, and suppression on in-phase to opposed-phase MRI were measured for adrenal masses. RESULTS: The norcholesterol uptake rate, CT attenuation value, and MR suppression index showed the sensitivity of 60%, 82%, and 100%, respectively, for functioning adenomas of <2.0 cm, and 96%, 79%, and 67%, respectively, for those of >or=2.0 cm. A statistically significant correlation was observed between size and norcholesterol uptake, and between CT attenuation value and MR suppression index. Regarding norcholesterol uptake, the adenoma-to-contralateral gland ratio was significantly higher in cortisol releasing than in aldosterone-releasing adenomas. CONCLUSIONS: The norcholesterol uptake rate was reliable for characterization of adenomas among adrenal masses of >or=2.0 cm. CT attenuation value and MR suppression index were well correlated with each other, and were useful regardless of mass size.     

肾上腺髓性脂肪瘤的影像诊断

目的 探讨肾上腺髓性脂肪瘤的影像学特征及鉴别诊断。方法 11例经手术及病理证实的肾上腺髓性脂肪瘤患者术前均经B超与CT诊断，其中9例又经MRI检查。对全部病例获自上述3种影像手段的所有资料进行了回顾性分析。结果 研究证实，肾上腺髓性脂肪瘤具有特征性影像表现。11例患者术前定位、定性诊断准确率，B超为63．6％(n=7)，CT与MRI均为100％(n=11)。结论 CT是确诊本病的首选方法，而各种影像特征的综合分析对本病确诊和鉴别诊断起关键作用。     

The role of gallium-67 scan in defining the extent of disease in an endemic deep mycosis,paracoccidioidomycosis: a predominantly multifocal disease

The tools currently used to evaluate the extent of paracoccidioidomycosis (PCM) may be of limited value in detecting subclinical lesions. The aim of this study was to verify the role of gallium-67 whole-body scan in evaluating the extent of disease of 65 patients with active PCM. The (67)Ga scan findings were compared with the results of clinical evaluation, chest radiography and/or high-resolution computed tomography (CT), abdominal ultrasound (US) or CT, laryngoscopy, CT or magnetic resonance imaging (MRI) of the head, and technetium-99m methylene diphosphonate bone scan, obtained before treatment. Clinically unsuspected lesions were detected by imaging procedures in 21 patients (32%), mainly in the lungs (n=11), adrenals (n=6), and superficial (n=3) and deep lymph nodes (n=14). (67)Ga scan detected 100% of the cases with subclinical involvement in the lungs. Scintigraphy was superior to chest radiography in demonstrating lung disease (94% vs 81%). The lymphatic lesions were demonstrated by (67)Ga scan in all the clinically suspected cases and in nearly all unsuspected cases, and also revealed more extensive involvement than was clinically suspected in many of them. There was good agreement between (67)Ga scan and the other imaging procedures for the initial detection of thoracic and abdominal lymph nodes and bone involvement. (67)Ga imaging detected most cases of laryngopharyngeal disease with active inflammatory lesions found at indirect laryngoscopy. On the other hand, (67)Ga scan failed to demonstrate most of the adrenal and CNS lesions detected by abdominal US/CT and head CT/MRI. In conclusion, (67)Ga imaging is a useful tool for evaluating the location and extent of suspected and unsuspected lesions in PCM. It could serve as a screening method before the use of other diagnostic procedures, particularly in the detection of lung, superficial and deep lymph node and bone involvement.     

Localization of pheochromocytoma: MIBG [correction of MIGB], CT, and MRI correlation

Nineteen patients (8 M, 11F) ranging in age from 15 - 67 yr old (mean = 39 yr) with clinically diagnosed pheochromocytomas were prospectively evaluated with 131I metaiodobenzyl-guanidine (MIBG) scintigraphy (n = 19), computed tomography (CT) (n = 19), and magnetic resonance imaging (MRI) (n = 17) in order to determine their relative diagnostic efficacy. Pathologic confirmation was obtained in all 19 patients: 13 intraadrenal and six extraadrenal with metastases in five (Table 1). All three imaging modalities were in agreement in 11 of 14 completed examinations (79%). MIBG and CT agreed in 16 of the 19 patients in whom both were performed (84%). MIBG/MR and CT/MR results were concordant in 12 of 14 (86%) and 13 of 14 (93%) jointly completed examinations, respectively. There was one false-negative (FN) MIBG scan, two FN CT scans, and one FN MR scan. MIBG, CT, and MRI are complementary procedures with MIBG providing more specific functional information and the latter two superior anatomic detail. MIBG scintigraphy is recommended as the initial localizing study of choice (especially for the detection of extraadrenal disease and postoperative recurrence), as a guide for CT and/or MR and specific functional confirmation of their findings. Although MRI is capable of imaging in multiple planes (without exposure to ionizing radiation or the need for i.v. contrast material) with superior contrast compared to CT, it is expensive and has poor patient cooperation. However, it may be capable of differentiating pheochromocytomas from other adrenal masses on the basis of signal characterization.     

The effects of carbidopa on uptake of 6-18F-Fluoro-L-DOPA in PET of pheochromocytoma and extraadrenal abdominal paraganglioma.

6-(18)F-fluoro-l-3,4-dihydroxyphenylalanine ((18)F-DOPA) PET is a useful tool for the detection of certain neuroendocrine tumors, especially with the preadministration of carbidopa, an inhibitor of DOPA decarboxylase. Whether carbidopa also improves (18)F-DOPA PET of adrenal pheochromocytomas and extraadrenal paragangliomas is unknown. The aim of this study was to investigate the sensitivity of (18)F-DOPA PET in the detection of paraganglioma and its metastatic lesions and to evaluate whether tracer uptake by the tumors is enhanced by carbidopa. METHODS: Two patients with nonmetastatic adrenal pheochromocytoma, and 9 patients with extraadrenal abdominal paraganglioma (1 nonmetastatic, 8 metastatic), underwent whole-body CT, MRI, baseline (18)F-DOPA PET, and (18)F-DOPA PET with oral preadministration of 200 mg of carbidopa. The dynamics of tracer uptake by these lesions and the physiologic distribution of (18)F-DOPA in normal tissues were recorded. RESULTS: Seventy-eight lesions were detected by CT or MRI, 54 by baseline (18)F-DOPA PET (P = 0.0022 vs. CT/MRI), and 57 by (18)F-DOPA PET plus carbidopa (P = 0.0075 vs. CT/MRI, not statistically significant vs. baseline). In reference to findings on CT and MRI, the sensitivities of baseline (18)F-DOPA PET were 47.4% for lesions and 55.6% for positive body regions, versus 50.0% (lesions) and 66.7% (regions) for (18)F-DOPA PET plus carbidopa (neither is statistically significant vs. baseline). Compared with baseline, carbidopa detected additional lesions in 3 (27%) of 11 patients. Carbidopa increased the mean (+/-SD) peak standardized uptake value in index tumor lesions from 6.4 +/- 3.9 to 9.1 +/- 5.6 (P = 0.037). Pancreatic physiologic (18)F-DOPA uptake, which may mask adrenal pheochromocytoma, is blocked by carbidopa. CONCLUSION: Carbidopa enhances the sensitivity of (18)F-DOPA PET for adrenal pheochromocytomas and extraadrenal abdominal paragangliomas by increasing the tumor-to-background ratio of tracer uptake. The sensitivity of (18)F-DOPA PET for metastases of paraganglioma appears to be limited.