Sensitivity of 6-[F-18]fluoro-L-dihydroxyphenylalanine positron emission tomography for localizing tumors causing catecholamine excess

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Background: Positron emission tomography (PET) using the catecholamine precursor 6-[F-18]fluoro-L-dihydroxyphenylalanine (18F-DOPA) has emerged as promising technique to localize tumors with catecholamine excess. This study investigated the sensitivity of 18F-DOPA PET, compared to 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy and computer tomography (CT)/ magnetic resonance imaging (MRI) in patients with catecholamine excess. Methods: In a single center prospective study 18F-DOPA PET was compared to 123I-MIBG and CT/MRI in patients with catecholamine excess. The performance of each imaging modality was analyzed for individual patients and individual lesions. 18F-DOPA PET, 123I-MIBG, and CT/MRI were compared using a composite reference standard derived from all available imaging, clinical and histological information. Sensitivities were calculated and discordance between imaging techniques was compared. 18F-DOPA PET uptake was measured to determine whole body metabolic burden. Correlations between 18F-DOPA PET imaging and biochemical data were evaluated. Results: 48 patients were included. The tumor localization was found in 45 patients, 43 with 18F-DOPA PET, 31 with 123I-MIBG and 32 with CT/MRI, resulting with surgery in final diagnosis of pheochromocytoma in 40, adrenal hyperplasia in 2, paraganglioma in 2, ganglioneuroma in 1 and 3 unknown (as yet no lesion detected). Per patient based analysis showed sensitivities for 18F-DOPA PET, 123I-MIBG and CT/MRI of 90, 65 and 67% (P<.01 18F-DOPA PET vs 123I-MIBG, P<.01 18F-DOPA PET vs CT/MRI, P=1.0 123I-MIBG vs CT/MRI). Corresponding sensitivities in the lesion based analysis were 73, 48 and 44%, respectively (P<.001 for both 18F-DOPA PET vs 123I-MIBG and vs CT/MRI, P=.51 123I-MIBG vs CT/MRI). The 8F-DOPA PET+CT/MRI combination was superior to 123I-MIBG+CT/MRI (93 vs 76%, P<.001) Whole body metabolic burden measured with 18F-DOPA PET correlated with plasma free normetanephrine (r=.82) and 24h urinary total normetanephrine (r=.84) and metanephrine (r=.57). Conclusions: The sensitivity of 18F-DOPA PET to localize tumors with catecholamine excess is superior to either 123I-MIBG scintigraphy or CT/MRI.

No significant financial relationships to disclose.

Primary pheochromocytoma extending into the right atrium: report of a case and review of the literature

Pheochromocytoma rarely extends locally into the vena cava or the right atrium. We report a case of malignant pheochromocytoma with growth into the inferior vena cava, extending into the right atrium, address clinical aspects of this tumour and review the literature on this malignancy. Pre-operative work-up of this tumour should include measurements of urinary vanillyl mandelic acid and cathecholamine excretion, MRI and spiral CT of the abdomen and thorax. After the diagnosis is made the patient should be treated with catecholamine alpha-receptor blockade and if necessary with subsequent beta-receptor blockade. An aggressive surgical approach is always warranted, even in cases with very large localized tumours, because surgery has been shown to lead to relief of symptoms and to prolong survival in cases otherwise deemed irresectable. The optimal surgical exposure is obtained via a transsternal midline thoraco-laparotomy. If feasible, a combination of cardiopulmonary bypass, hypothermia, cardiac arrest and exsanguination procedures should be used. In case of local of tumour remnants after surgery or distant metastases treatment options are secondary surgery, tumour embolization, or treatment with radioactive labelled drugs, including(131)I-MIBG.

Increased local cytostatic drug exposure by isolated hepatic perfusion: a phase I clinical and pharmacologic evaluation of treatment with high dose melphalan in patients with colorectal cancer confined to the liver

A phase I dose-escalation study was performed to determine whether isolated hepatic perfusion (IHP) with melphalan (L-PAM) allows exposure of the liver to much higher drug concentrations than clinically achievable after systemic administration and leads to higher tumour concentrations of L-PAM. Twenty-four patients with colorectal cancer confined to the liver were treated with L-PAM dosages escalating from 0.5 to 4.0 mg kg(-1). During all IHP procedures, leakage of perfusate was monitored. Duration of IHP was aimed at 60 min, but was shortened in eight cases as a result of leakage from the isolated circuit. From these, three patients developed WHO grade 3-4 leukopenia and two patients died due to sepsis. A reversible elevation of liver enzymes and bilirubin was seen in the majority of patients. Only one patient was treated with 4.0 mg kg(-1) L-PAM, who died 8 days after IHP as a result of multiple-organ failure. A statistically significant correlation was found between the dose of L-PAM, peak L-PAM concentrations in perfusate (R = 0.86, P< or =0.001), perfusate area under the concentration-time curve (AUC; R = 0.82, P<0.001), tumour tissue concentrations of L-PAM (R = 0.83, P = 0.011) and patient survival (R = 0.52, P = 0.02). The peak L-PAM concentration and AUC of L-PAM in perfusate at dose level 3.0 mg kg(-1) (n = 5) were respectively 35- and 13-fold higher than in the systemic circulation, and respectively 30- and 5-fold higher than reported for high dose oral L-PAM (80-157 mg m(-2)) and autologous bone marrow transplantation. Median survival after IHP (n = 21) was 19 months and the overall response rate was 29% (17 assessable patients; one complete and four partial remissions). Thus, the maximally tolerated dose of L-PAM delivered via IHP is approximately 3.0 mg kg(-1), leading to high L-PAM concentrations at the target side. Because of the complexity of this treatment modality, IHP has at present no place in routine clinical practice.

MRI of liver metastases: limitation of spleen-liver model in optimizing pulse sequences

The spleen-liver model, as a predictor for contrast-to-noise ratio (C/N) in liver metastases, was verified for seven sequences in 22 patients with 70 colorectal metastases. Optimization of conventional spin-echo, T1-magnetization-prepared gradient-echo and fat frequency-selective presaturation inversion-recovery fast spin echo can be done using the spleen-liver model. C/N of liver-spleen and liver-metastases, however, differed significantly on our T1 gradient-echo and T2-weighted fast spin-echo images, with and without fat-selective saturation.

Comparison of inversion-recovery gradient- and spin-echo and fast spin-echo techniques in the detection and characterization of liver lesions

PURPOSE

To compare respiratory-triggered inversion-recovery (IR) gradient- and spin-echo (GRASE) magnetic resonance (MR) imaging with respiratory-triggered T2-weighted fast spin-echo (SE) imaging in the diagnosis of liver metastases.

MATERIALS AND METHODS

In this prospective study, two radiologists independently identified focal hepatic lesions on respiratory-triggered IR GRASE and respiratory-triggered fast SE MR images in 28 consecutive patients with 186 (135 malignant and 51 benign) proved lesions. A combination of findings at surgery, intraoperative ultrasonography (US), and histologic examination served as the standard of reference. Contrast-to-noise ratios (CNRs) were obtained from 86 lesions larger than 10 mm.

RESULTS

The sensitivity in the detection of liver metastases was, independent of lesion size and observer, higher for IR GRASE imaging (55%) than for fast SE imaging (44%-50%) (observer 1, P = .014; observer 2, P = .21). Confidence levels with IR GRASE imaging were higher, but not significantly so, than those with fast SE imaging (P < .098). Both observers characterized liver lesions better with IR GRASE than with fast SE imaging (observer 1, P = .04; observer 2, P = .48). The metastasis-liver CNR was significantly higher (P = .012) with IR GRASE imaging.

CONCLUSION

The respiratory-triggered IR GRASE sequence is a fast alternative to the respiratory-triggered fast SE sequence in the evaluation of suspected liver metastases.

Interconnections of the upper ventral rami of the human sacral plexus: a reappraisal for dorsal rhizotomy in neurostimulation operations

The extension of a dorsal rhizotomy in bladder stimulation patients is partly determined by connections between the ventral rami of the second, third, and fourth sacral spinal nerves. The literature is inconclusive on interconnections of these ventral rami in the human sacral plexus. The sacral plexuses of ten human cadavers were dissected in this gross anatomy study. In nine cases a branch connecting the ventral rami of the second and third sacral spinal nerves was found. Electron microscopy demonstrated the presence of thick myelinated fibers in this branch. In the male plexuses this branch formed the only link between the second sacral spinal segment and the pelvic plexus. The ventral ramus of the second sacral nerve always contributed to the pudendal nerve, whereas involvement of the ventral rami of the first and third sacral nerves differed individually and intersexually.

Magnetic resonance imaging of the so-called cerebral cryptic angiomas

Cerebral cryptic angiomas are vascular malformations with variable histological appearance, but with similar radiological features. Angiography does not usually visualize the lesion. Computer tomography often detects the malformation, but frequently fails to make classify correctly. With magnetic resonance imaging (MRI) the cryptic angioma is studied best on T2 weighted images. The pattern of signal intensities differs both among and within the lesions. Evidence of small hemorrhages of different ages and flow phenomena are seen in all malformations. A total of 51 angiomas were demonstrated in 38 patients by MRI (excluding one patient with a very large number of angiomas). Enhanced or plain CT scans depicted respectively 16 and 6 lesions. In one case angiography was the only way to detect an angioma. Currently, MRI is the most sensitive method for the detection of cerebral cryptic angiomas.