Magnetic resonance imaging or metaiodobenzylguanidine scintigraphy for the demonstration of paragangliomas? Correlations and disparities

Adrenal Emergencies

The adrenal glands drive physiologic homeostasis, with dysregulation in any direction causing multisystem dysfunction. Adrenal excess states include hyperaldosteronism which manifests with refractory hypertension and electrolyte abnormalities including hypernatremia and hypokalemia. Paragangliomas including pheochromocytoma can cause multisystem end-organ dysfunction due to catecholaminergic storm, which require rapid blood pressure control with phentolamine and identification of lesions amenable to surgical resection. Adrenal insufficiency states in contrast can result in hypotension and decompensation refractory to vasopressor administration, requiring adrenal supplementation via hydrocortisone.

A retrospective comparison between 68Ga-DOTA-TOC PET/CT and 18F-DOPA PET/CT in patients with extra-adrenal paraganglioma

PURPOSE

(18)F-Fluoro-L-dihydroxyphenylalanine ((18)F-DOPA) PET offers high sensitivity and specificity in the imaging of nonmetastatic extra-adrenal paragangliomas (PGL) but lower sensitivity in metastatic or multifocal disease. These tumours are of neuroendocrine origin and can be detected by (68)Ga-DOTA-Tyr(3)-octreotide ((68)Ga-DOTA-TOC) PET. Therefore, we compared (68)Ga-DOTA-TOC and (18)F-DOPA as radiolabels for PET/CT imaging for the diagnosis and staging of extra-adrenal PGL. Combined cross-sectional imaging was the reference standard.

METHODS

A total of 5 men and 15 women (age range 22 to 73 years) with anatomical and/or histologically proven extra-adrenal PGL were included in this study. Of these patients, 5 had metastatic or multifocal lesions and 15 had single sites of disease. Comparative evaluation included morphological imaging with CT and functional imaging with (68)Ga-DOTA-TOC PET and (18)F-DOPA PET. The imaging results were analysed on a per-patient and a per-lesion basis. The maximum standardized uptake value (SUVmax) of each functional imaging modality in concordant tumour lesions was measured.

RESULTS

Compared with anatomical imaging, (68)Ga-DOTA-TOC PET and (18)F-DOPA PET each had a per-patient and per-lesion detection rate of 100% in nonmetastatic extra-adrenal PGL. However, in metastatic or multifocal disease, the per-lesion detection rate of (68)Ga-DOTA-TOC was 100% and that of (18)F-DOPA PET was 56.0%. Overall, (68)Ga-DOTA-TOC PET identified 45 lesions; anatomical imaging identified 43 lesions, and (18)F-DOPA PET identified 32 lesions. The overall per-lesion detection rate of (68)Ga-DOTA-TOC PET was 100% (McNemar, P < 0.5), and that of (18)F-DOPA PET was 71.1% (McNemar, P < 0.001). The SUVmax (mean ± SD) of all 32 concordant lesions was 67.9 ± 61.5 for (68)Ga-DOTA-TOC PET and 11.8 ± 7.9 for (18)F-DOPA PET (Mann-Whitney U test, P < 0.0001).

CONCLUSION

(68)Ga-DOTA-TOC PET may be superior to (18)F-DOPA PET and diagnostic CT in providing valuable information for pretherapeutic staging of extra-adrenal PGL, particularly in surgically inoperable tumours and metastatic or multifocal disease.

Imaging characterization of benign and malignant pheochromocytoma or paraganglioma: comparison between MIBG uptake and MR signal intensity ratio

OBJECTIVE

We compared metaiodobenzylguanidine (MIBG) uptake and magnetic resonance (MR) signal intensity ratio in differentiating benign and malignant disease in patients with pheochromocytoma or paraganglioma.

METHODS

Eighteen patients (9 men, mean age 37 ± 8 years) with pheochromocytoma or paraganglioma underwent MR imaging and iodine-131 MIBG scintigraphy. MR signal intensity ratio was measured on T1 and T2-weighted images using region of interest analysis and intensity ratio of MIBG uptake was calculated for each tumor lesion on 48 h images.

RESULTS

A total of 28 tumor lesions was analyzed of which 12 were benign and 16 malignant. MIBG uptake intensity ratio was significantly higher in malignant lesions compared to benign (5.2 ± 2.4 and 2.9 ± 1.4, respectively, p < 0.01). On the contrary, no significant difference in tumor size and MR signal intensity ratio between malignant and benign tumor lesions was observed.

CONCLUSIONS

In patients with pheochromocytoma or paraganglioma, iodine-131 MIBG uptake is able to differentiate between benign and malignant disease, while MR imaging is not useful for this purpose. The higher MIBG uptake observed in malignant lesions could reflect major tumor storage of catecholamines compared to benign lesions.

123I-metaiodobenzylguanidine (MIBG) scintigraphy for the detection of adrenal and extra-adrenal phaeochromocytomas: CT and MRI correlation

CONTEXT

Evidence regarding the accuracy of [(123)I] metaiodobenzylguanidine (MIBG) imaging for phaeochromocytoma localization is currently limited to small series.

OBJECTIVE

We present the largest series of primary phaeochromocytomas in which the performance of [(123)I]MIBG has been evaluated and correlated with cross-sectional imaging.

DESIGN

We identified 76 patients with both preoperative [(123)I]MIBG and cross-sectional imaging for confirmed primary phaeochromocytoma between 1995 and 2005 at our institution. This comprised 60 adrenal tumours in 55 patients and 33 extra-adrenal tumours in 23 patients (2 patients had both adrenal and extra-adrenal tumours). Phaeochromocytoma metastases were not evaluated.

MAIN OUTCOME MEASURE(S)

[(123)I]MIBG studies were independently reviewed and correlated with CT and MRI examinations, as well as tumour functional status, to identify features that may predict a false negative [(123)I]MIBG result.

RESULTS

The overall sensitivity of [(123)I]MIBG was 75%. Tumour detection was lower for extra-adrenal (58%) vs. adrenal (85%) phaeochromocytomas (P = 0.005). For extra-adrenal tumours, [(123)I]MIBG demonstrated 8 of 14 carotid body, 2 of 2 intrathoracic, 8 of 14 retroperitoneal and 2 of 3 pelvic phaeochromocytomas. Overall, MRI and CT demonstrated 68 of 68 and 72 of 74 primary phaeochromocytomas, respectively. Tumour size correlated with [(123)I]MIBG uptake for adrenal (P = 0.009) but not extra-adrenal tumours. When tumours were adjusted for size, no other imaging feature or functional status correlated with [(123)I]MIBG negativity, although two large [(123)I]MIBG negative adrenal tumours contained large areas of necrosis or haemorrhage.

CONCLUSIONS

Extra-adrenal and small adrenal phaeochromocytomas are more likely to result in false negatives on [(123)I]MIBG. Tumoural necrosis or haemorrhage do not consistently relate to [(123)I]MIBG uptake, although adrenal phaeochromocytomas containing minimal solid tissue due to extensive necrosis may predict a negative [(123)I]MIBG result.

Familial carotid body tumours: is there a role for genetic screening?

Objective:

Carotid body tumours are rare lesions which are familial in 10 per cent of cases. In this paper, we demonstrate the clinical applicability of predictive genetic testing for familial carotid body tumours.

Methods:

We report a case manifesting with multiple carotid body tumours, in which subsequent genetic testing demonstrated a germline mutation which could be traced across generations. We review the diagnosis and management of carotid body tumours in the familial setting, together with the strategies presently available to screen individuals from susceptible families.

Conclusions:

The recent advent of a predictive genetic test for familial carotid body tumours offers a novel means of pre-selecting those at risk, so as to minimise screening costs and patient morbidity. Early diagnosis of lesions is essential to allow early intervention, reducing surgical morbidity and progression to malignancy.

Sensitivity and positive predictive value of CT, MRI and 123I-MIBG scintigraphy in localizing pheochromocytomas: A prospective study

AIM

To establish a standardized non-invasive imaging protocol for patients with pheochromocytoma undergoing surgery.

METHODS

A series of 32 consecutive patients (16 men, 16 women; median age 43 years, range 15-71 years) with biochemically confirmed pheochromocytoma underwent computed tomography (CT) scanning, magnetic resonance imaging (MRI) and meta-[I]iodobenzylguanidine (MIBG) whole-body scintigraphy prior to adrenalectomy or excision of extra-adrenal tumour (paraganglioma).

RESULTS

At final pathology no malignant pheochromocytomas were found. The tumour was right-sided in 16 (50%) patients, left-sided in 13 (41%), extra-adrenal (sympathetic ganglia, upper abdomen) in two (6%) and bilateral in one (3%) patient. Overall, the median greatest diameter (size) of the tumour was 35 mm (range, 15-90 mm). The sensitivity of CT, MRI and MIBG scintigraphy was 90%, 93% and 91%, and the specificity was 93%, 93% and 100%, respectively. The three patients with false negative scintigraphy had an intra-adrenal tumour, ranging from 20 to 50 mm in size. The presence of necrosis within the mass might justify the lack of significant uptake of radiopharmaceutical in two patients, and the small size (15 mm) of the mass in the other. There were two false positive results with both CT and MRI, and no false positive MIBG scintigraphy, which had the highest (100%) positive predictive value. The combination of MRI+MIBG scintigraphy reached 100% sensitivity and positive predictive value.

CONCLUSION

Our data suggest that this imaging protocol should be used in all patients with biochemically confirmed pheochromocytoma.

Case report: patient with multiple paragangliomas treated with long acting somatostatin analogue

Paragangliomas of the head and neck are uncommon neoplasms. They are usually benign, but tend to be locally invasive. Although surgical resection remains the definitive treatment, important issues about management arise when such lesions are inoperable. Beneficial effects of octreotide treatment have already been reported in a malign paraganglioma case. Here we report a 24 year old female with familial, bilateral, multiple paraganglioma in the head and neck region, who firstly presented with pulsatile tinnitus and hearing loss in her left ear. After embolization was performed, she underwent operation twice because of the gross tumor mass. No significant change in tumor size was determined after the operations, however there were no distant metastases. Although she experienced hypertension attacks, no hormonal overproduction was found in repeated measurements. As the tumor was unresectable, new alternative therapies were sought. Octreotide scintigraphy was positive in the tumoral tissue, so we began to treat her with somatostatin analogue octreotide. After a 16 month follow up period, an improvement of the performance status, the near normalisation of attacks and stabilization of tumor growth were achieved. However, in the last three visits, she began to experience symptoms more frequently and it had been necessary to increase the octreotide dose. She is now well and being followed up. In conclusion, the beneficial effects of octreotide treatment could be quantified by clinical, tumor and scintigraphic criteria. These data suggest that octreotide can be useful in the treatment of inoperable paragangliomas.

[Pheochromocytoma in internal medicine: distinctive features and place of 123I MIBG scintigraphy]

PURPOSE

Pheochromocytoma diagnosis uses the localization of the tumour, particularly thanks to MIBG scintigraphy. The aims of this study were to evaluate the sensibility and specificity of this exam, his opportunity towards clinical and biological profile of patients with pheochromocytoma suspicion in Internal Medicine and towards others techniques of imaging. We tried to define the most effective and least expensive approach of pheochromocytoma diagnosis.

METHOD

This study was carried out over 15 years period on 80 patients in Internal Medicine who underwent 123I MIBG scintigraphy for pheochromocytoma suspicion.

RESULTS

Among the 80 patients who underwent 123I MIBG scintigraphy, only 18 suffered from a pheochromocytoma. A very few symptoms were specific, like the triad "headaches, sweating, palpitations" whose onlyone third of patients was concerned by. The diagnosis approach carried on with urine catecholamine measurement, who was specific when metanephrines were increased whatever their levels and when normetanephrines were higher or equal than 1,5 time the norme. Then, abdominal CT or MRI scanning and 123I MIBG scintigraphy were performed for localization of the tumor. The sensibility of scintigraphy was 83%, its specificity was 89%. That is comparable with other studies about 131I MIBG.

CONCLUSION

Prescription of MIBG scintigraphy in Internal Medicine appears to be excessive: 77,5% of patients don't have a pheochromocytoma. It is related to the lack of specific symptoms, the wrong positives in urine normetanephrines measurement and the discovery of incidentaloms by CT scanning. The scintigraphy should be used like a topographic and not a diagnosis exam.

18F-DOPA positron emission tomography for the detection of glomus tumours

The purpose of this study was to evaluate (18)F-DOPA whole-body positron emission tomography ((18)F-DOPA PET) as a biochemical imaging approach for the detection of glomus tumours. (18)F-DOPA PET and magnetic resonance imaging (MRI) were performed in ten consecutive patients with proven mutations of the succinate dehydrogenase subunit D ( SDHD) gene predisposing to the development of glomus tumours and other paragangliomas. (18)F-DOPA PET and MRI were performed according to standard protocols. Both methods were assessed under blinded conditions by two experienced specialists in nuclear medicine (PET) and diagnostic radiology (MRI). Afterwards the results were compared. A total of 15 lesions (four solitary and four multifocal tumours, the latter including 11 lesions) were detected by (18)F-DOPA PET. Under blinded conditions, (18)F-DOPA PET and MRI revealed full agreement in seven patients, partial agreement in two and complete disagreement in one. Eleven of the 15 presumed tumours diagnosed by (18)F-DOPA PET were confirmed by MRI. The correlation of (18)F-DOPA PET and MRI confirmed three further lesions previously only detected by PET. All of them were smaller than 1 cm and had the signal characteristics of lymph nodes. For one small lesion diagnosed by PET, no morphological MRI correlate could be found even retrospectively. No tumour was detected by MRI that was negative on (18)F-DOPA PET. All tumours diagnosed by MRI showed a hyperintense signal on T2-weighted images and a distinct enhancement of contrast medium on T1-weighted images. The mean tumour size was 1.5+/-0.5 cm. (18)F-DOPA PET seems to be a highly sensitive metabolic imaging procedure for the detection of glomus tumours and may have potential as a screening method for glomus tumours in patients with SDHD gene mutations.

Vertebral metastatic chemodectoma: imaging and therapeutic octreotide. Case report

The authors report on the use of external-beam radiotherapy and octreotide in a 32-year-old woman who presented with spinal cord compression secondary to metastatic chemodectoma. Scintigraphy studies were used to confirm the presence of somatostatin receptors. Magnetic resonance imaging, and in particular spinal angiography, were performed to define the extent of spinal metastatic disease. The literature on current investigation and management of vertebral metastatic chemodectoma is reviewed.

Visualisation of a paraganglioma by technetium-99m-sestamibi scintigraphy

A 68-yr-old woman presented to our observation with multinodular goiter and a contiguous right laterocervical mass. In spite of ultrasound, technetium and iodine scan, CT and fine-needle biopsy, the precise origin of the mass remained uncertain. On additional multi-phase sestamibi scan, the neck region showed an early high uptake rapidly decreasing over time in the laterocervical mass, and a persistent inhomogeneous distribution in the thyroid gland. This behavior suggested that the laterocervical mass could derive from an anatomical structure other than the thyroid. Surgical exploration established the extrathyroid nature of the laterocervical mass and the histological examination confirmed that it was a typical paraganglioma. This finding is in keeping with a recent report of positive sestamibi uptake in a cervical paraganglioma, although our case showed a more rapid kinetic. This tumor should be therefore taken into consideration in the differential interpretation of focal sestamibi uptake.

111Indium pentetreotide scan detection of familial paragangliomas

Approximately 10% of head and neck paragangliomas are familial. Magnetic resonance imaging (MRI) is reported to be the best method for screening these families. 111Indium pentetreotide (Octreoscan) scintigraphy has been shown to be a sensitive indicator of neural crest tumors such as paragangliomas. Early diagnosis and treatment of familial paragangliomas (FP) would decrease the morbidity of tumor excision. Patients from two kindred with FP were scanned 24 hours after intravenous injection with approximately 6 millicuries of 111Indium pentetreotide. The entire body was imaged. Areas of increased uptake were further imaged with MRI. Altogether, five patients had positive 111Indium pentetreotide scans. Two unsuspected glomus tympanicums and bilateral carotid body tumors were identified. Three people tested had no abnormal uptake. There were no untoward reactions to the nuclide. 111Indium pentetreotide scanning is a safe, noninvasive method for early diagnosis of FP and is useful in detecting multicentric lesions. Patients suspect for FP are undergoing 111Indium pentetreotide imaging and followed up with MRI of the involved site if positive.

The diagnostic utility of somatostatin receptor scintigraphy in oncology

Somatostatin receptor scintigraphy (SRS) with the diethylenetriaminopentaacetic-acid-conjugated somatostatin analogue [111In-DTPA-D-Phe1] octreotide, also known as 111In-pentetreotide, is a new non-invasive modality for the evaluation of tumours that express receptors for somatostatin. These receptors are present on neuroendocrine and other tumours, including lymphomas and some breast cancers. In oncology SRS is a promising diagnostic tool for localizing primary tumours, staging, control and follow-up after therapy, and for identification of patients who may benefit from therapy with unlabelled octreotide or, in the future, with radiolabelled octreotide. In the past few years many small and large studies investigating various aspects of SRS have been reported. In this review the value of SRS in the management of individual tumour types is explored. For many tumours the best sensitivity in lesion detection is only achieved by very careful imaging after the administration of at least 200 MBq 111In-pentetreotide. On the basis of the current experience the main value of SRS in oncology is in the staging and evaluation of gastroenteropancreatic tumours, paragangliomas, small-cell lung cancer and lymphomas. Promising areas for SRS are the evaluation of breast cancer, non-medullary thyroid cancer and melanoma, and initial results with targeted radionuclide therapy using radiolabelled octreotide have been reported.

Magnetic resonance imaging differentiation of adrenal masses at 1.5 T: T2-weighted images, chemical shift imaging, and Gd-DTPA dynamic studies

The purpose of our study was to assess the potential role of spin-echo (SE), chemical shift, and gadolinium-enhanced magnetic resonance imaging (MRI) in the differentiation of adrenal masses. Seventy-two adrenal masses (26 nonhyperfunctioning adenomas, 16 aldosterone-secreting adenomas and 6 other different benign cortical masses, 18 pheochromocytomas, and 6 malignant masses) in 63 patients were evaluated with spin-echo sequences, chemical shift imaging (CSI) and gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA) dynamic studies. Ratios and indices of signal intensity for all examined MRI methods were calculated and examined for significance of difference between different types of adrenal masses. Quantitative magnetic resonance evaluation of adrenal masses showed significant differences (at least alpha < 0.01) between nonhyperfunctioning adenomas vs. pheochromocytomas or vs. malignant lesions or vs. aldosterone-secreting adenomas and between pheochromocytomas vs. malignant lesions. The most specific indicators of adrenal mass character proved to be the CSI ratio based on opposed-phase and in-phase two-dimensional fast low-angle shot (FLASH) images, reflecting lipid content in the lesion, and Gd-DTPA dynamic studies ratios reflecting contrast agent inflow and washout in the lesion: WoMAX/LAST and Dyn1.2-3.2. There was no overlap of CSI ratio between adenomas and pheochromocytomas. The overlap of ranges of CSI ratio between nonhyperfunctioning adenomas and aldosterone-secreting adenomas was only 18.5%. There was no overlap of WoMAX/LAST ratio between adenomas and pheochromocytomas, or adenomas and malignant lesions. The overlap of ranges of Dyn1.2-3.2 ratio between pheochromocytomas and malignant lesions was only 17.6%. MRI enables good visualization and specific characterization of adrenal masses. The optimal MRI protocol for the adrenal region is presented.

Nonfunctioning malignant paraganglioma of the posterior mediastinum with spinal cord compression. A case report

STUDY DESIGN

Case report and review of the literature.

OBJECTIVE

To present a case with an uncommon nonfunctioning malignant paraganglioma of the posterior mediastinum with compression of the spinal cord. An update survey is given with respect to diagnostic, histopathologic, and therapeutic aspects of paragangliomas.

SUMMARY OF BACKGROUND DATA

Paragangliomas in the posterior mediastinum are uncommon and rarely may produce spinal cord compression. To illustrate the low incidence, only two cases of paraganglioma of the posterior mediastinum were reported by the Mayo Clinic, Rochester, Minnesota, during a 40-year period.

METHOD

Case report and review of the literature.

RESULT

The diagnosis was made by modern imaging techniques (computed tomography, magnetic resonance imaging, and metaiodobenzylguanidine scan) and verified by computed tomography guided per thoracic puncture. A wide local resection was performed; the patient is disease-free 1 year after surgery.

CONCLUSION

The uncertainty of prognosis and possibility of local recurrence of paragangliomas even after a long period emphasizes the importance of wide local surgical resection with or without adjuvant therapy and makes long-term follow-up and continued surveillance of the patient mandatory.