[A new multislice measurement sequence for the complete dynamic MR examination of the larger organs: application to the breast]

ROBITOM-robot for biopsy and therapy of the mamma

MR-Mammography reaches a high sensitivity in detecting breast carcinomas of 3 mm in size at least. In cooperation with the Institute of Diagnostic and Interventional Radiology of the Friedrich-Schiller-University of Jena, a manipulator has been developed by the IMB, which combines the advantages of MRM imaging with a minimal invasive biopsy and a possible subsequent therapy. Referring to this ROBITOM I was introduced in November 1999 as worldwide first, precise operating manipulator system in the ISO center of a closed MR, at RSNA in Chicago. Clinical trials started at 22. November 2000. The experiences and results of these tests were brought into the following prototype ROBITOM II, that is currently developed at the IMB. The completion of this Prototype is planned at the end of 2002.

Robotic system for biopsy and therapy of breast lesions in a high-field whole-body magnetic resonance tomography unit

RATIONALE AND OBJECTIVES

With magnetic resonance mammography, significant progress has been achieved in the diagnosis of small breast cancers. However, biopsy and therapy of suspicious lesions must take place at a later time. Diagnosis and simultaneous biopsy and therapy in one single examination would considerably reduce costs, strain on the patient, and side effects.

METHODS

ROBITOM (Robotic system for biopsy and interventional therapy of mammary lesions) is used to approach a lesion found in the breast in an image-controlled manner under a high magnetic field (eg, 1.5 T). The robotic system works in the direct vicinity of the isocenter of a magnet and consists of a trocar, coaxial sleeve, biopsy needle, laser applicator, and a control and driving unit. It contains a rack, a driving unit along the three coaxes of space, and a gripping unit for instruments or biopsy sample removal. The system has six degrees of freedom.

RESULTS

In vitro experiments in pig liver including eight targets (vitamin E capsules, 4 mm in diameter) were performed. All eight capsules were hit precisely by the robotic biopsy system. The procedure was performed directly in the isocenter of a 1.5-T whole-body scanner.

CONCLUSIONS

The system allows the coordinates of a lesion in the breast to be approached in a high magnetic field without shifting the patient. A combination of imaging with biopsy and subsequent therapy (eg, laser therapy or cryotherapy) seems to be feasible in the future.

Breast magnetic resonance imaging

Breast MRI is becoming an important tool for the improved management of breast cancer. The technical attributes of high contrast, high-resolution breast MRI acquisitions are summarized. The fundamentals of image interpretation are outlined, including lesion enhancement, morphological features, and extent categories. The indications for breast MRI include compromised mammography, staging of disease within the breast and adjacent structures, difficult histology, and other special diagnostic situations. Patients with compromised mammography include previous surgery, radiographically dense breasts, and silicone augmentation. The improved determination of disease extent aids in the management of breast conservation treatment. Certain lesions, particularly lobular carcinoma and ductal carcinoma in situ, can be better managed with the information available with breast MRI. Other potential indications are also discussed, including patients presenting with positive axillary nodes and no known primary, women with a high risk of malignancy, and recently postoperative breasts with positive margins. The need for MRI stereotaxis is reviewed, with indications and potential solutions. The potential future roles for MRI-directed interstitial hyperthermia are outlined.

Dynamic magnetic resonance imaging of the contralateral testis in patients with malignant tumor of the testis

OBJECTIVES

Dynamic magnetic resonance imaging (MRI) was tested using a dynamic technique to evaluate the possibility of differentiating between normal contralateral testes and testes with a carcinoma in situ.

METHODS

Since March 1990, 20 volunteers and 21 patients with a malignant tumor of the testis were examined in a field strength of 1.5 Tesla (Philips Gyroscan S15) with a multislice T1-weighted fast field echo sequence before and every 63 seconds after the injection of 0.1 mmol/kg gadolinium-diethylenetriamine pentaacetic acid.

RESULTS

Significant differences (p < 0.001) in signal changes of contralateral testes were detected in dynamic MRI. This increased signal enhancement is detected even 45 months after orchiectomy in the contralateral testes. The signal increase is reduced in follow-up controls. These observations are explained by an increased perfusion which seems to be induced after a postoperative irritation, an unspecific inflammation, or postoperative bleeding.

CONCLUSIONS

To avoid false-positive diagnoses of tumors or carcinomata in situ in contralateral testes, these increased enhancements caused by postoperative reactions have to be kept in mind.