Carsten Altehoefer

18F-DOPA positron emission tomography for tumour detection in patients with medullary thyroid carcinoma and elevated calcitonin levels

Abstract. In spite of the availability of numerous procedures, diagnostic imaging of tumour manifestations in patients with medullary thyroid carcinoma and elevated calcitonin levels is often difficult. In the present study, the new procedure of fluorine-18 dihydroxyphenylalanine positron emission tomography (18F-DOPA PET) was compared with the established functional and morphological imaging methods. After evaluation of the normal distribution of 18F-DOPA, 11 patients with medullary thyroid carcinoma were examined using 18F-DOPA PET. Results of 18F-fluorodeoxyglucose (18F-FDG) PET, somatostatin receptor scintigraphy (SRS) and morphological tomographic imaging (CT/MRI) were available for all patients. All individual procedures were evaluated without reference to prior information. Data assessment for each patient was based on cooperation between experienced radiologists and specialists in nuclear medicine, who considered all the available findings (histological results, imaging, follow-up studies). This cooperation served as the gold standard against which the results of the individual procedures were evaluated. A total of 27 tumours were studied [three primary tumours (PT)/local recurrence (LR), 16 lymph node metastases (LNM) and eight organ metastases (OM)]. 18F-DOPA PET produced 17 true-positive findings (2 PT/LR, 14 LNM, 1 OM), 18F-FDG PET 12 (2 PT/LR, 7 LNM, 3 OM), SRS 14 (2 PT/LR, 8 LNM, 4 OM) and morphological imaging 22 (3 PT/LR, 11 LNM, 8 OM). The following sensitivities were calculated with respect to total tumour manifestations: 18F-DOPA PET 63%, 18F-FDG PET 44%, SRS 52%, morphological imaging 81%. Thus, the morphological imaging procedures produce the best overall sensitivity, but the specificity for PT/LR (55%) and LNM (57%) was low. With respect to lymph node staging, the best results were obtained with 18F-DOPA PET. 18F-DOPA PET is a new functional imaging procedure for medullary thyroid carcinoma that seems to provide better results than SRS and 18F-FDG PET. Moreover, the data indicate that no single procedure provides adequate diagnostic certainty. Therefore, 18F-DOPA PET is a useful supplement to morphological diagnostic imaging, improving lymph node staging and enabling a more specific diagnosis of primary tumour and local recurrence.

MR imaging of the carpal tunnel

OBJECTIVE Investigations were conducted regarding changes of carpal tunnel shape during wrist motion and the variations of space for the median nerve as well as the preoperative signs of carpal tunnel syndrome (CTS) and the postoperative restitution. METHODS Axial MR images (1.0 T) were performed at the level of the distal radioulnar joint, pisiforme bone and hook of hamate level of 20 wrists of patients with clinical symptoms of CTS and further 20 wrists of volunteers. This was conducted with the wrist in neutral position, 45 degrees extension and 45 degrees flexion. T2-weighted signal intensity of the median nerve were measured in 18 patients pre- and postoperatively. RESULTS The increase of the cross-sectional area of the median nerve at the pisiform level and the flattening of the median nerve at the hook of hamate level as well as the volar bowing of the flexor retinaculum at the pisiform and hook of hamate level were significantly greater in patients with CTS than in those with normal wrists (P < 0.05-0.001). In postoperative follow-up studies the distal flattening of the median nerve recovered in 94%. The signal intensity of the median nerve on T2-weighted images decreased in 67%. CONCLUSIONS Flexion at the pisiform and hamate level as well as extension at the pisiform level narrows the space available for the median nerve potential leading to compression of the median nerve. MR imaging is accurate and reliable for diagnosis and postoperative follow-up of CTS.

Comparative diagnostic accuracy of magnetic resonance imaging and immunoscintigraphy for detection of bone marrow involvement in patients with malignant lymphoma.

PURPOSE To compare the diagnostic accuracy of magnetic resonance imaging (MRI) and immunoscintigraphy (IS) for detection of bone marrow infiltration in malignant lymphoma. PATIENTS AND METHODS In 32 patients with Hodgkins disease (HD) or non-Hodgkins lymphoma (NHL), MRI of the axial skeleton and whole-body IS using technetium-99m (99mTc)-labeled monoclonal antibodies were reviewed and compared with iliac crest biopsies. Criterion for marrow infiltration was a positive biopsy or concordant positive results of MRI and IS. RESULTS In 16 patients (50%), MRI, IS, and iliac crest biopsies were negative for marrow infiltration. Iliac crest biopsy showed infiltration in only four patients (13%). Infiltration was missed in two of 32 patients with IS and in one patient with MRI. In one additional patient, MRI was false-positive because of pelvic hematopoietic hyperplasia. A subset of nine patients (28%) with negative biopsies had bone marrow involvement according to MRI and IS with identical location and pattern of infiltration. In eight of these nine patients, diagnostic imaging indicated marrow involvement only in noncrest marrow. Subsequent biopsy confirmed infiltration in five patients. The clinical course suggested true-positive imaging results in the remaining four patients. Two patients (6%) remained equivocal. Overall concordance of MRI and IS for marrow infiltration was 88% (28 of 32 patients). CONCLUSION Diagnostic imaging is essential for optimal staging in malignant lymphoma, as blind biopsies appear to have low sensitivity for bone marrow infiltration because of frequent involvement in noncrest marrow. both imaging modalities show a high rate of detection of bone marrow infiltration.

Ectopic Thyroid Gland in the Porta Hepatis and Lingua

A rare case of an ectopic thyroid gland in the porta hepatis and in the tongue in an asymptomatic euthyroid 24-year-old woman is reported. A solitary inhomogeneous, hypoechogenic and hyperechogenic mass in the porta hepatis was accidentally discovered by ultrasonography. Subsequent computed tomography demonstrated a heterogeneous, well-defined tumor with small calcifications without signs of environmental invasion. A hemangioma and focal nodular hyperplasia were excluded by blood pool and hepatobiliary scintigraphy. Surprisingly, fine-needle aspiration cytology revealed normal thyroid tissue. (123)I-scintigraphy confirmed the presence of ectopic dual thyroid tissue in the hepatic porta and lingua. At clinical inspection the lingual thyroid gland was palpable and visible, and appeared solid and spheroidal. The subhepatic, ectopic thyroid mass was resected. Postoperatively, thyroid hormone replacement was started to prevent an enlargement of the lingual thyroid. Today, 4 years after surgery, the patient remains euthyroid.

Radiological findings in Boerhaave's syndrome

The aim was to define the diagnostic value of chest radiography, esophagography, and computed tomography (CT) in patients with Boerhaaves syndrome. CT findings in 14 patients (11 male, 3 female; mean age: 60 years; median age: 66 years; age range: 36–78 years) with spontaneous esophageal perforation were retrospectively reviewed and compared to those of esophagography (n=11) and chest radiography (n=14). In six patients unenhanced CT scans were available; in ten patients (2/10 patients had an unenhanced CT before) a contrast-enhanced CT was performed as an emergency investigation. In 5/14 patients additional oral contrast medium was given. Chest radiography revealed pleural effusions in 9/14 and infiltrates in 9/14 patients. Pneumothorax and pneumopericardium were observed in two patients each. Pneumomediastinum was seen in three patients. Two chest radiographs were normal. Esophagography performed in 11 patients demonstrated contrast medium extravasation at a supradiaphragmatic level in seven patients, indicating esophageal perforation with esophagopleural fistula, and a submucosal contrast medium collection in four cases. Unenhanced CT scans revealed four intramural hematomas with typical localization. Unenhanced and contrast-enhanced CT demonstrated periesophageal air collections indicating esophageal perforation in all patients. Pleural effusions were seen in 11/14 and infiltrates in 8/14 patients. Contrast medium extravasation was observed in 5/14 patients, whereas a thickening of the esophageal wall was depicted in 11/14 patients. Periaortic air tracks (n=7), pneumothorax (n=3), pneumomediastinum (n=6), and mediastinal fluid collections (n=7) were depicted in CT. By demonstrating periesophageal air tracks suggestive of esophageal perforation, CT reveals the decisive criteria for diagnosing Boerhaaves syndrome and should therefore be performed in the diagnostic work-up of patients in whom this syndrome is part of the differential diagnosis.

Comparative diagnostic value and therapeutic relevance of magnetic resonance imaging and bone marrow scintigraphy in patients with metastatic solid tumors of the axial skeleton

PURPOSE To evaluate the comparative impact of magnetic resonance imaging (MRI) and bone marrow scintigraphy (BMS) in bone marrow metastases of solid tumors. METHODS In 20 patients with solid tumors MRI of the axial skeleton and whole-body BMS were retrospectively reviewed. Detectability of metastases, extent of disease and therapeutic implications were assessed. RESULTS In 15/20 (75%) patients MRI and BMS concordantly revealed bone marrow metastases of the axial skeleton. In nine of these 15 patients (60%) MRI showed more metastases. Local radiotherapy or surgery was performed in seven of these cases (78%). BMS detected additional metastases of the appendicular skeleton in 8/15 (53%) patients. In 4/20 cases (20%) the imaging findings were discordant. In three patients with degenerative changes (n=2) or lipoma (n=1) BMS was false positive. In another patient BMS failed to detect metastases proven by MRI and clinical follow-up resulting in subsequent radiation therapy. One patient had normal bone marrow. CONCLUSION MRI appears to be more sensitive and specific in the detection of bone marrow metastases in the axial skeleton and is of clinical importance for subsequent local therapy.

Contrast enhanced MR angiography in the assessment of relevant stenoses in occlusive disease of the pelvic and lower limb arteries: diagnostic value of a two-step examination protocol in comparison to conventional DSA

INTRODUCTION/OBJECTIVES Contrast-enhanced MRA (ce-MRA) has been claimed by many authors as a replacement of conventional angiography evaluating peripheral arterial occlusive disease. However, reliable detection of relevant stenoses (>70%) has to be provided for planning vascular interventions. Only few data in the literature focuses on this crucial problem. The purpose of this study was to evaluate this topic using a two-step body-coil-based MRA protocol. METHODS AND PATIENTS Forty three patients presenting with 82 stenoses >/=50% and 61 stenoses >70% on conventional catheter angiogram received fast Gadolinium-DTPA-enhanced high resolution 3D MR angiography at 1.5 T covering the pelvic and peripheral vascular tree in two examination steps using the body-coil. The data were evaluated double-blinded by three readers distinguishing moderate (50-70%) from severe stenoses (>70%). RESULTS Overall sensitivity/specificity/accuracy was 84/60/70% evaluating 143 segments. Specificity was rather poor in the iliac (58%) and crural (50%) region and moderate in the femoral and popliteal level (73%). The negative predictive value ranged between 78 and 91%. The grade of stenosis tend to be overestimated rather than underestimated in all levels with positive predictive values between 55 and 78%. DISCUSSIONS AND CONCLUSIONS Body-coil-based contrast-enhanced MRA has limited potential in distinguishing moderate from severe stenoses in peripheral occlusive disease. Overestimations are more common than underestimations. Both occur mainly in small-sized crural arteries but also in larger iliac arteries where vessel course in partition direction may cause inadequacy between voxel size and lumen diameter in severe stenosis.

Optimization of Contrast-Enhanced MR Angiography of the Hands with a Timing Bolus and Elliptically Reordered 3D Pulse Sequence

Our objective was to optimize bolus administration and sequence setting in gadolinium-enhanced magnetic resonance (MR) angiography of the hands. Elliptically reordered three-dimensional (3D) spoiled gradient-echo sequence with non-slab-selective radio frequency excitation was optimized according to the measurements of arterial and venous time–signal curves in 21 patients. Great variations in bolus arrival time and arterio-venous transit time could be observed. In most patients high-quality arterial depiction could be obtained with minor venous contamination. Contrast-to-noise, spatial resolution, and selective arterial filling is still a challenge for 3D MR angiography of the hand but can be optimized using Gadolinium-BOPTA and a dedicated pulse sequence setting with exact bolus timing.

Chest wall infiltration by lung cancer: value of thin-sectional CT with different reconstruction algorithms.

Abstract. The aim of this investigation was to evaluate whether thin-sectional CT with different reconstruction algorithms can improve the diagnostic accuracy with regard to chest wall invasion in patients with peripheral bronchogenic carcinoma. Forty-one patients with intrapulmonary lesions and tumor contact to the thoracic wall as seen on CT staging underwent additional 1-mm CT slices with reconstruction in a high-resolution (HR) and an edge blurring, soft detail (SD) algorithm. Five criteria were applied and validated by histological findings. Using the criteria of the intact fat layer, HRCT had a sensitivity of 81 % and a specificity of 79 %, SD CT had a sensitivity of 96 % and a specificity of 78 %, and standard CT technique had a sensitivity of 50 % and a specificity of 71 %, respectively. Regarding changes of intercostal soft tissue, HRCT achieved a sensitivity of 71 % and a specificity of 96 %, SD CT had a sensitivity of 94 % and a specificity of 96 % (standard CT technique: sensitivity 50 % and specificity 96 %) . For the other criteria, such as pleural contact area, angle, and osseous destruction, no significant differences were found. Diagnostic accuracy of chest wall infiltration can be improved by using thin sectional CT. Especially the application of an edge-blurring (SD) algorithm increases sensitivity and specificity without additional costs.

Imaging findings in the rare catastrophic variant of the primary antiphospholipid syndrome

Abstract. We report imaging findings in a case of the rare catastrophic variant of antiphospholipid syndrome (CAPS) characterized by widespread microvascular occlusions, which may lead to multiple organ failure. We present a case of a 66-year-old woman with bone marrow necrosis, acute acalculous cholecystitis (AAC), focal liver necrosis, subtle patchy splenic infarctions, and bilateral adrenal infarction. The demonstration of multiple microvascular organ involvement (three or more) is crucial for the diagnosis of the catastrophic variant of APS. This can be performed radiologically intra-vitam. Imaging can even reveal subclinical microinfarctions, which are often only diagnosed at autopsy.