68Ga-labelled peptides in the management of neuroectodermal tumours.

Neuroectodermal tumours arise from chromaffin cells and possess the ability to secrete catecholamines. They are generally rare and may occur in association with a variety of hereditary syndromes such as MEN-2A and 2B, neurofibromatosis type 1 and von Hippel-Lindau disease. The most common types are phaeochromocytoma arising from the adrenal medulla and paraganglioma of extra-adrenal origin. Phaeochromocytomas tend to be benign and are often associated with a gene mutation if the disease is bilateral, while paragangliomas are often malignant, have a more aggressive nature and tend to metastasize. There are no specific histological or immunohistochemical features that indicate the malignant potential and the diagnosis of malignancy can only be established by the presence of distant metastases. Therefore, imaging can play a vital role in the diagnosis, localization, staging and assessment of spread. Traditionally, this is achieved with a combination of cross-sectional (CT and MRI) and functional ((123)I-MIBG or (111)In-octreotide) imaging. However, these modalities are not adequate and achieve moderate sensitivity. The introduction of (68)Ga-DOTA peptide in PET/CT imaging has led to improved receptor targeting and superb PET resolution, as well as accurate localization of lesions. The use of this technique in neuroectodermal tumours has been shown to be superior to all available modalities, but the available data are limited and larger studies are awaited to establish its role in the management of these tumours.

Silastic injection for vocal fold medialization resulting in a false-positive finding on F18 FDG-PET/CT.

A false-positive uptake of F18-fluorodeoxyglucose (FDG) on positron-emission tomography/computed tomography (PET/CT) can result in confusion and misinterpretation of scans. Such uptakes have been previously described after injection of polytetrafluoroethylene (Teflon) into the vocal folds. Similarly, vocal fold injection of silicone elastomer (Silastic) can result not only in a false-positive FDG uptake on PET/CT, but also in chronic inflammation. We report a case of increased FDG uptake in a vocal fold after Silastic injection that was misinterpreted as a malignancy in a 70-year-old woman who had metastatic carcinoma of the stomach.

Incidental finding of a hepatic angiomyolipoma.

Angiomyolipoma (AML) of the liver is a very uncommon lipomatous neoplasm, usually asymptomatic and incidentally identified. We describe the imaging findings of a histologically confirmed case using different modalities (US, CT, and MRI). We review and correlate current literature with our imaging and histological findings.

68Ga-DOTA-TATE PET vs. 123I-MIBG in identifying malignant neural crest tumours.

PURPOSE: We aimed to compare imaging with (123)I-MIBG and (68)Ga-DOTA-TATE in neural crest tumours (NCT) to see if the latter could offer more advantage in detecting extra lesions and have higher sensitivity for malignant lesions. PROCEDURES: We retrospectively reviewed 12 patients (M = 10, F = 2; age range 20-71 years) with NCT (phaeochromocytomas = 7, paragangliomas = 4, medullary thyroid cancer = 1) who underwent both (68)Ga-DOTA-TATE positron emission tomography (PET) or PET/computed tomography (CT) and (123)I-MIBG single-photon emission computed tomography within 6 months. Visual assessment of all lesions and measurement of target/non-target (T/N) ratio in selected lesions were performed. Five patients (aged 50 or less) had SDHB screening results correlated with imaging results of both radiopharmaceuticals. All patients had contrast-enhanced CT and/or other cross-sectional imaging. RESULTS: (68)Ga-DOTA-TATE PET showed tumour lesions in ten out of 12 patients with confirmed disease, while (123)I-MIBG showed lesions in five out of 12 patients. In one patient, both (68)Ga-DOTA-TATE PET and (123)I-MIBG were negative, but CT, magnetic resonance imaging, and 2-deoxy-2-[(18)F]fluoro-D-glucose PET scans identified a lesion in the thorax. (68)Ga-DOTA-TATE and (123)I-MIBG detected a total of 30 lesions, of which 29/30 were positive with (68)Ga-DOTA-TATE and 7/30 with (123)I-MIBG. We also found higher incidence of SDHB positive results in patients with positive (68)Ga-DOTA-TATE. CONCLUSION: Our limited data suggest that (68)Ga-DOTA-TATE is a better imaging agent for NCT and detects significantly more lesions with higher T/N ratio compared to (123)I-MIBG. (68)Ga-DOTA-TATE was more likely to detect malignant lesions as indicated by correlating imaging results with SDHB screening.

Intradermal lymphoscintigraphy at rest and after exercise: a new technique for the functional assessment of the lymphatic system in patients with lymphoedema.

AIM: The aim of this study was to evaluate the effect of implementing a new technique, intradermal injection lymphoscintigraphy, at rest and after muscular exercise on the functional assessment of the lymphatic system in a group of patients with delayed or absent lymph drainage. METHODS: We selected 44 patients (32 women and 12 men; 15 of 44 with upper limb and 29 of 44 with lower limb lymphoedema). Thirty of 44 patients had bilateral limb lymphoedema and 14 of 44 had unilateral disease; 14 contralateral normal limbs were used as controls. Twenty-three patients had secondary lymphoedema after lymphadenectomy and the remaining 21 had idiopathic lymphoedema. Each of the 44 patients was injected with 50 MBq (0.3-0.4 ml) of (99m)Tc-albumin-nanocolloid, which was administered intradermally at the first interdigital space of the affected limb. Two planar static scans were performed using a low-energy general-purpose collimator (acquisition matrix 128 x 128, anterior and posterior views for 5 min), and in which drainage was slow or absent, patients were asked to walk or exercise for 2 min. A postexercise scan was then performed to monitor and record the tracer pathway and the tracer appearance time (TAT) in the inguinal or axillary lymph nodes. RESULTS: The postexercise scans showed that (i) 21 limbs (15 lower and six upper limbs) had accelerated tracer drainage and tracer uptake in the inguinal and/or axillary lymph nodes. Two-thirds of these showed lymph stagnation points; (ii) 27 limbs had collateral lymph drainage pathways; (iii) in 11 limbs, there was lymph drainage into the deeper lymphatic channels, with unusual uptake in the popliteal or antecubital lymph nodes; (iv) six limbs had dermal backflow; (v) three limbs did not show lymph drainage (TAT=not applicable). TAT=15 + or - 3 min, ranging from 12 to 32 min in limbs with lymphoedema versus 5 + or - 2 min, ranging from 1 to 12 min in the contralateral normal limbs (P<0.001). CONCLUSION: Intradermal injection lymphoscintigraphy gives a better imaging of the lymph drainage pathways in a shorter time, including cases with advanced lymphoedema. In some patients with lymphoedema, a 2-min exercise can accelerate tracer drainage, showing several compensatory mechanisms of lymph drainage. The effect of the exercise technique on TAT and lymphoscintigraphy findings could result in a more accurate functional assessment of lymphoedema patients.

The typical appearance of the inferior accessory ossicle of the anterior arch of the atlas.

The inferior accessory ossicle of the anterior arch of the atlas is quite rare and has been described in the literature by only few articles. However, these articles have only included plain radiographs in the description. In our case, the above ossicle is illustrated in two imaging modalities, plain radiography and CT imaging. The importance of this ossicle lies in its recognition as only an anatomical variant and not to be confused with other pathological conditions such as a fracture.