MRI of the Prostate in Germany: Online Survey among Radiologists.

PURPOSE: To assess structural, technical, and communicative aspects of dedicated MR examinations of the prostate (MRP) offered by radiologists in Germany. MATERIALS AND METHODS: We conducted an eight-item online survey among members of the German Radiology Society (DRG). Radiological institutions were asked about their structure, i.e., either hospital department (HD) or private practice (PP), number of board-certified radiologists, postal regions, number of MRPs in 2011, MR technology and MR sequences applied, ways to communicate results, and feedback from referring physicians on results of subsequent tests and procedures. Submissions were cleared of redundancies and anonymized. Differences in the number of positive replies to each item were statistically significant at p < 0.05 for two-tailed testing in 2 x 2 tables. RESULTS: The survey represented board-certified radiologists in 128 institutions (63 HDs and 65 PPs) in 67/95 German postal regions (71%). Almost two-thirds of institutions performed 11 to 50 MRPs in 2011, more often at 1.5 T (116/128, 91%) than at 3.0 T (36/128, 28%), and most frequently with surface coils (1.5 T, 88/116, 76%; 3.0 T, 34/36, 94%; chi-square, 1.9736, 0.1 < p < 0.25). About two-thirds of 1.5 T users and 90% of 3.0 T users applied at least one functional MR modality (diffusion-weighted imaging, dynamic contrast-enhanced imaging, or MR spectroscopy) for MRP. Reports including graphic representations of the prostate were applied by 21/128 institutions (16%). Clinical feedback after MRP to radiologists other than upon their own request was infrequent (HDs, 32-45%, PPs, 18-32%). CONCLUSION: MRP was a widely available, small-volume examination among radiologists in Germany in 2011. The technology mainstay was a 1.5 T surface coil examination including at least one functional MR modality. Dedicated reporting and feedback mechanisms for quality control were underdeveloped. KEY POINTS: MRI of the prostate was available in at least 67 of 95 German postal regions (71%) in 2011. MRI of the prostate was most often performed at 1.5 T without an endorectal coil in Germany in 2011. At least two thirds of MRI-examinations of the prostate included both T2WI and at least one functional MR test (mostly DWI, less frequently MRS or DCE) in Germany in 2011. Structured reporting including graphic elements was offered by less than 20% of participating radiological institutions. Feedback to radiologists from referring physicians on subsequent test results in patients with MRI of the prostate most frequently came only upon special request by the radiologist.

Cystic fibrosis in adults: short-term and long-term reproducibility of the Brody score for lung morphology in low-dose MDCT scans.

PURPOSE: The semi-quantitative Brody score measures the severity of cystic fibrosis (CF)-related lung disease. We investigated the short-term (28 - 60 days) and long-term (2 - 7 years) intra- and inter-observer reproducibility of the Brody score in low-dose multidetector row computed tomography examinations performed in inspiration (LDCTs) of adult CF patients. MATERIALS AND METHODS: Composite Brody scores and respective underlying bronchiectasis, mucus plugging, peribronchial thickening, parenchymal opacity, and hyperinflation subscores were evaluated twice (time interval, 1 - 84 months) by each of 3 independent radiologists (1 - 20 years of professional diagnostic radiology experience) in LDCTs (4 - 64 rows, 120 KVp, 10 - 15  mAs/slice, CTDIw approx. 1.0  mGy, effective dose approx. 0.5  mSv) of 15 adult patients with CF-related lung disease (8 female, 7 male, age, 18 - 50 years, mean, 33 years). RESULTS: The average reproducibility of the Brody score was within +/-7 % (range, 2 - 30 %) between radiologists, and +/-6 % (3 - 12 %) within radiologists (short-term, 28 - 60 days, 4 %, 0 - 12 %, long-term, 2 - 7 years, 12 %, 1 - 36 %). For the different subscores, the reproducibility was within +/-25 % (15 - 41 %) between radiologists and +/-23 % (12 - 46 %) within radiologists. CONCLUSION: The Brody score shows high average inter-observer reproducibility in LDCTs of adult CF patients. The Brody score also demonstrates high average intra-observer reproducibility if subsequent assessments are made within 28 - 61 days. With time intervals of 2 - 7 years between subsequent evaluations, however, intra-observer reproducibility decreases. Respective subscores each demonstrate lower intra- and inter-observer reproducibility than does the composite Brody score.

[CT urography in women with primary or recurrent pelvic tumors : background and initial experiences]. / CT-Urographie bei Frauen mit primären oder rezidivierenden Beckentumoren : Hintergrund und erste Erfahrungen.

Malignant tumors of the female pelvis account for 12-13% of newly diagnosed solid neoplasms among women in the USA and Germany. German guidelines advocate diagnostic imaging for local recurrence and metastasis while there are no recommendations for primary tumors. As excretory urography has been replaced by the excretory phase of computed tomography urography (CTU) in many institutions, two independent observers retrospectively evaluated CTUs of primary or recurrent female pelvic tumors to rule out associations between CTU findings and subsequent urologic measures. Among 31 CTUs of 27 women (age 29-84 years, mean 57 years) with 15 primary and 13 recurrent tumors, 83-100% of unremarkable proximal, middle and distal ureter segments were completely delineated in the excretory phase (delay 6-29 min, mean 16 min). The most common pathological findings included distal ureter obstruction (n=19, 61%), bladder compression (n=13, 42%) and bladder invasion (n=8, 26%). Out of 20 pathologically altered urinary tracts 8 were subsequently subjected to urologic measures (2-tailed Fisher exact test, p=0.0215) but none of the 10 unremarkable urinary tracts were treated. It appears that CTU is a sensible pre-therapeutic test for the urinary tract for primary and recurrent female pelvic tumors.

[Diffusion-weighted MRI of the prostate]. / Diffusionsgewichtete MRT der Prostata.

Diffusion-weighted magnetic resonance imaging (DWI) can complement MRI of the prostate in the detection and localization of prostate cancer, particularly after previous negative biopsy. A total of 13 original reports and 2 reviews published in 2010 demonstrate that prostate cancer can be detected by DWI due to its increased cell density and decreased diffusiveness, either qualitatively in DWI images or quantitatively by means of the apparent diffusion coefficient (ADC). In the prostate, the ADC is influenced by the strength of diffusion weighting, localization (peripheral or transitional zone), presence of prostatitis or hemorrhage and density and differentiation of prostate cancer cells. Mean differences between healthy tissue of the peripheral zone and prostate cancer appear to be smaller for ADC than for the (choline + creatine)/citrate ratio in MR spectroscopy. Test quality parameters vary greatly between different studies but appear to be slightly better for combined MRI and DWI than for MRI of the prostate alone. Clinical validation of DWI of the prostate requires both increased technical conformity and increased numbers of patients in clinical studies.

[An unusual case of non-traumatic enophthalmos]. / Ungewöhnlicher Fall eines atraumatischen Enophthalmus.

An extensive spectrum of differential diagnoses has to be considered when a patient presents with enophthalmos. The most common causes of this presentation include orbital trauma or contraction and atrophy of the orbital contents secondary to scleroderma or radiotherapy. However radiologists also have to consider less common causes of enophthalmos, such as the imploding antrum syndrome or the ethmoid silent sinus syndrome. The latter involves the ethmoidal cells and results in medial orbital wall implosion. Along with the case presentation the pathogenesis, incidence and differential diagnoses of ethmoid silent sinus syndrome are elucidated. In particular the differentiation from normal anatomical variants, such as dehiscent lamina papyracea is discussed.

[Imaging modalities for primary diagnosis and staging of prostate cancer]. / Bildgebende Verfahren bei Primärdiagnose und Staging des Prostatakarzinoms.

The new S3 guideline on prostate cancer includes imaging modalities applied for early detection, primary diagnosis, and staging of prostate cancer. Detection and primary diagnosis are based on digital rectal examination, serum PSA levels, and prostate biopsy. Among the imaging modalities, MRI shows the highest test quality parameters. Although MRI cannot replace biopsy to prove prostate cancer, its high negative predictive value can help to reduce the number of subsequent biopsies after negative prostate biopsy. For T-staging, MRI also demonstrates the highest test quality parameters. Its clinical application is limited, since therapeutic consequences are restricted. Due to its high specificity, MRI can save unnecessary pelvic lymph node dissections in patients at high risk for lymph node metastasis (N-staging). Risk-adjusted bone scans, complemented by additional radiological examinations if necessary, remain the standard to assess hematogenous metastasis (M staging).

Catheter-based intraluminal optical coherence tomography versus endoluminal ultrasonography of porcine ureter ex vivo.

OBJECTIVES: To compare the distinction of tissue layers of porcine ureters ex vivo between optical coherence tomography (OCT) and endoluminal ultrasonography (ELUS). Catheter-guided OCT is a new method of intraluminal microstructural imaging, with a spatial resolution of 10-20 mum. METHODS: Porcine ureters and kidneys were obtained fresh from the municipal slaughtery, cannulated with a 7F catheter sheath, flushed with normal saline solution, and marked on the outside with surgical suture. Between the marked positions, images were obtained from within the ureter lumen using OCT (M1, Lightlab, Westport, MA) and ELUS at 40 MHz. The distinction of the urothelium, lamina propria, and inner and outer muscle layers was rated as possible (1) or impossible (0) by 2 independent observers (O1, O2). The rates of distinction were compared between OCT and ELUS image quadrants using the chi(2) test. RESULTS: Of the 224 OCT image quadrants and 144 ELUS image quadrants, OCT was superior to ELUS in the distinction of any wall layers (O1, chi(2)P = 68.1051, P < .001; O2, chi(2)P = 66.1630, P < .001), urothelium and lamina propria (O1, chi(2)P = 200.0750, P < .001; O2, chi(2)P = 240.0024, P < .001), and lamina propria and muscle layer (O1, chi(2)P = 38.8411, P < .001; O2, chi(2)P = 24.7536, P < .001) but was inconclusive for the inner and outer muscle layer (O1, chi(2)P = 260.3004, P < .001; O2, chi(2)P = 0.4992, P > .25). CONCLUSIONS: OCT was able to distinguish significantly better than ELUS between different wall layers of porcine ureter ex vivo. The feasibility of OCT in vivo and in the presence of pathologic wall thickening of the ureter remains to be demonstrated.

Intracranial germinoma as a very rare cause of panhypopituitarism in a 23-year old man.

A 23 year-old patient was referred to the endocrine outpatient clinic with the suspicion of diabetes insipidus as he complained of nycturia and polydipsia since 2-3 months. Further he presented with nausea, vomiting, loss of appetite, rapid weight loss, diffuse body pain and fatigue. No headache, blurred vision, or fever were reported. The clinical examination showed sexual infantilism (poor beard, pubic and axillary hair growth, small testis). The patient's skin was strikingly pale as well as dry and scaly. Lymph node palpation was unremarkable. Endocrine evaluation revealed diabetes insipidus as well as complete anterior pituitary insufficiency. MR imaging demonstrated contrast-enhancing mass lesions at the pineal gland, hypothalamus, and anterior horn of lateral ventricles bilaterally. The localization pattern deemed to be highly suspicious for intracranial germinoma. As beta-HCG and AFP were negative in serum and cerebrospinal fluid the diagnosis of germinoma was confirmed histologically. After radiotherapy with cranio-spinal radiation therapy with 24 Gy followed by two weeks of local tumor boost with 16 Gy, the posttherapy MRI scan indicated complete tumor removal. This case demonstrates a very rare and potentially curable tumor as the cause of panhypopituitarism in adults.

Beam hardening artefacts occur in dental implant scans with the NewTom cone beam CT but not with the dental 4-row multidetector CT.

OBJECTIVES: The aim of this study was to examine beam hardening artefacts of the NewTom 9000 cone-beam computed tomography (CBCT) device compared with the Philips MX 8000 (4-row multidetector CT (MDCT)). METHODS: We modified a SawBone skull to become a standardized model for our study. The skull was used for scans with the NewTom 9000 CBCT device and a standard dental multi-detector CT (MDCT) at a comparable reconstruction resolution with a standard Straumann ITI 4.1 mm implant in four implant positions in the maxilla (first permanent premolar in the right maxilla region, second permanent molar in the right maxilla region, first permanent premolar in the left maxilla region and second permanent molar in the left maxilla region). Results were compared with construction data of the dental implant. An image quality assessment of the images from both devices was performed with four experienced physicians and statistically analysed with the two-tailed Wilcoxon test. RESULTS: Scans with the NewTom 9000 CBCT showed strong beam hardening artefacts in the form of a radiation beam shadow in all reconstructions compared with the MDCT. These imaging artefacts became stronger with greater distance from the centre of the scanned volume. These differences in the imaging quality were proved as significant in a quality evaluation by four experienced physicians (P<0.05). CONCLUSIONS: Visual spatial resolution of the NewTom 9000 CBCT was less accurate than the Philips MX 8000 MDCT in the imaging of metallic dental implants.

Perforation of the colon: a rare complication of hepatocellular carcinoma.

Direct infiltration of the colon by hepatocellular carcinoma (HCC) is a rare condition. Only a few reports can be found in the literature. Here we present a case of direct infiltration of the ascending colon by an exophytic growing HCC of the right posterior liver lobe, in which treatment with transarterial chemoembolization (TACE) had been performed. Tumor invasion became evident by abdominal pain and lower gastrointestinal bleeding. Diagnosis was established by contrast-enhanced multidetector computed tomography (CE-MDCT), demonstrating the direct tumor invasion with concomitant perforation of the infiltrated colon segment. Based on these findings, rapid and effective surgical treatment could be achieved.

[33 year old Libanese woman with recurrent haemoptysis and cystic lesion of the lung]. / 33-jährige Libanesin mit rezidivierenden Hämoptysen und zystischer Raumforderung in der Lunge.

A 33 year old woman from Lebanon presented with recurrent hemoptysis, subfebrile temperature, dyspnoe in stress, fatigue, weight loss, and pruritus. Serological tests and results from chest X-ray and computer tomography revealed cystic echinococcosis with pulmonary involvement. After refusal of surgical therapy a medical treatment with albendazole was implemented. Two months after the start of the therapy only a small fibrotic residuum in the lung was seen. A spontaneous healing success seems unlikely because of the duration of the pulmonary cyst and the progressive symptoms before treatment.

Multidetector CT of the kidney.

The technological development of multidetector CT offers new possibilities for better imaging of organic structures that can be used in diagnosis of the kidney. The thinner slices allow a better spatial resolution, and slice fusion allows improved contrast resolution. The isotropic voxel has been realized in the latest 64-channel scanners. The image quality of arbitrarily reconstructed planes has arrived at the image quality of the scan plane. Faster scanning allows studies in different contrast phases, which is helpful for better discrimination of benign or malignant lesions especially in the highly vascularized kidney. Different phases of contrast uptake can be differentiated (arterial, cortico-medullary, nephrographic, and excretory phase). Multidetector CT brings along the risk of increased dose due to thinner slice collimation and overranging phenomena. Indications for CT investigation of the kidney include urolithiasis, tumor diagnosis and staging, renal trauma, and vascular disease. Even in children, special indications for CT of the kidney remain in polytrauma and tumor staging. Multidetector CT of the kidney has become a very valuable tool in urology, but a careful protocol strategy is mandatory.

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model.

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm x 32 cm x 42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88-30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current-time product (15-100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875-1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.

[Intravascular optical coherence tomography: differentiation of atherosclerotic plaques and quantification of vessel dimensions in crural arterial specimens]. / Intravaskuläre optische Kohärenztomographie: Unterscheidung verschiedener Plaquetypen und Vermessung von Gefässdimensionen in atherosklerotischen Unterschenkelarterien.

PURPOSE: Intravascular optical coherence tomography (OCT) is a new technique based on infrared light that visualizes the arteries with a resolution of 10-20 microm. Intravascular ultrasound (IVUS) is the current in vivo reference standard and provides a resolution of 100-150 microm. This study compared OCT to IVUS and histopathology with respect to the ability to differentiate atherosclerotic plaques and quantify vascular dimensions in peripheral crural arteries ex vivo. MATERIALS AND METHODS: 50 segments of atherosclerotic arteries derived from five amputated human lower extremities were examined. The different plaque types (fibrous, high-lipid content, calcified) were assigned by two independent examiners, and the sensitivity and specificity of OCT in comparison with histopathology as well as intra- and interobserver consensus were calculated. A comparison of OCT with IVUS addressed the parameters: luminal area (LA), vascular wall area (VA) and plaque area (PA). RESULTS: When comparing OCT and histopathology with respect to the differentiation of various plaque types, sensitivities of 81 % and specificities of 89 % for fibrous plaques, of 100 % and 93 % for lipid-rich plaques and of 80 % and 89 % for calcified plaques were achieved (overall correlation 83 %). Intra- and interobserver consensus was very high (kappa = 0.86 and kappa = 0.89, p < 0.001, respectively). There was also a high correlation between quantitative measurements (Bland-Altman plot [LA]: mean bias, 0.1 mm(2) accuracy +/- 1.8 mm(2), r = 0.95 [p < 0.001] Bland-Altman plot [VA]: mean bias, 0.3 mm(2) accuracy +/- 2.3 mm(2), r = 0.94 [p < 0.001] Bland-Altman plot [PA]: mean bias, 0.4 mm(2) accuracy +/- 2.3 mm(2), r = 0.80 [p < 0.01]. CONCLUSION: OCT allows the differentiation of atherosclerotic plaque types in crural arteries with high accuracy compared to histopathology. Quantitative measurements show a high correlation with IVUS, the current reference standard.

[Low-dose spiral CT of the lung in the follow-up of non-malignant lung disease]. / Niedrigdosis-Spiral-CT des Thorax in der Verlaufskontrolle nichtmaligner Lungenerkrankungen.

PURPOSE: To assess image quality of chest CT with an 80 to 90 percent dose reduction in follow-up studies of patients with lung disease, dose and image quality of a low-dose protocol was investigated. MATERIALS AND METHODS: A follow-up low-dose CT (ND-CT, 120 kV, 10 mAs/slice, 3 mm slice thickness) was performed on 35 patients with non-malignant lung disease and compared with the initial standard dose CT (= SD-CT, 100 mAs/slice, 3 or 5 mm slice thickness). The dose was measured by thermo-luminescence in an Alderson phantom. Image quality was assessed by four independent radiologists in six perihilar, central and peripheral lung regions using a 4-point-scale ("very good", "good", "moderate", and "poor"). RESULTS: Effective dose was 0.5 mSv for ND-CT and 4.0 - 5.0 mSv for SD-CT. The ratings "very good"/"good" were given in the perihilar regions in ND-CT 97.5 % versus SD-CT 99.3 % (n. s.), in the central regions in ND-CT 96.4 % versus SD-CT 94.6 % (n. s.), and in the peripheral regions in ND-CT 70.0 % versus SD-CT 88.2 % (p < 0.01). CONCLUSION: Follow-up CT of pulmonary structures in patients with chronic lung disease can be performed with substantial dose reduction. A decrease of image quality may result in peripheral lung regions.

[1H magnetic resonance spectroscopy of the prostate]. / 1H-MR-Spektroskopie der Prostata: Ein Uberblick.

PURPOSE: To provide a brief summary of important technical and biochemical aspects and current clinical applications of magnetic resonance spectroscopy (MRS) of the prostate. MATERIAL AND METHODS: Pertinent radiological and biochemical literature was searched and retrieved via electronic media (Medline, PubMed). Basic concepts of MRS of the prostate and its clinical applications were extracted to provide an overview. RESULTS: The prostate lends itself to MRS due to its unique production, storage, and secretion of citrate. While healthy prostate tissue demonstrates high levels of citrate and low levels of choline that marks cell wall turnover, prostate cancer (PCA) utilizes citrate for energy metabolism and shows high levels of choline. The ratio of (choline + creatine)/citrate differentiates healthy prostate tissue and PCA. The combination of magnetic resonance imaging (MRI) and 3-dimensional MRS (3D-MRSI or 3D-CSI) of the prostate localizes PCA to a sextant of the peripheral zone of the prostate with sensitivity/specificity of up to 80/80%. Combined MRI and 3D-MRSI exceed the sensitivity and specificity of sextant biopsy of the prostate. When MRS and MRI agree on PCA presence, the positive predictive value is about 90%. In principle, combined MRI and 3D-MRSI recognize and localize remnant or recurrent cancer after hormone therapy, radiation therapy and cryo-surgery. CONCLUSIONS: Since it is non-invasive and radiation-free, combined MRI and 3D-MRSI lends itself to the planning of prostate biopsy and therapy as well as to post-therapeutic follow-up. For broad clinical application, it will be necessary to facilitate MRS examinations and their evaluation and make MRS available to a wider range of institutions.

[Cost effectiveness of screening procedures for early detection of prostatic carcinoma: an overview]. / Untersuchungen zur Kosteneffizienz von Screeningmassnahmen zur Früherkennung des Prostatakarzinoms: Ein Uberblick.

PURPOSE: The authors attempted to provide an overview of current concepts and the status of research in the field of cost effectiveness analysis (CEA) of screening for prostate cancer (PCA). MATERIAL AND METHODS: Basic concepts and methods of CEA were reviewed. Examples of CEA-related studies of PCA were obtained from pertinent literature through medical databases. RESULTS: Screening for PCA has so far been restricted to limited groups of health care recipients, usually within the framework of clinical trials. In those trials, screening for PCA usually results in higher numbers of PCAs being detected at lower average stages in a given population. As a consequence of screening, the rate of potentially curable PCAs increases. However, it has not yet been demonstrated that screening for PCA decreases PCA-related mortality or morbidity from metastatic PCA. On the other hand, additional costs are associated with the screening measure and with increased use of resources for diagnosis and treatment of the additional PCAs detected through screening. CONCLUSIONS: Throughout the European Union and North America, mass screening for PCA has not been implemented. This may chiefly be due to the current lack of information on long term benefits of PCA screening, particularly disease-specific survival. Currently, major studies are underway to assess the effects of PCA screening and its cost effectiveness. These studies include the US-American prostate, lung, colon and ovary trials (PLCO) and the European randomised study of Screening for Prostate Cancer (ERSPC).

Localized prostate cancer: effect of hormone deprivation therapy measured by using combined three-dimensional 1H MR spectroscopy and MR imaging: clinicopathologic case-controlled study.

PURPOSE: To determine the accuracy of combined magnetic resonance (MR) imaging and three-dimensional (3D) proton MR spectroscopic imaging in localizing prostate cancer to a sextant of the gland in patients receiving hormone deprivation therapy. MATERIALS AND METHODS: Combined MR imaging/3D MR spectroscopic imaging examinations were performed in 16 hormone-treated patients and 48 nontreated matched control patients before radical prostatectomy and step-section histopathologic analysis. At MR imaging, cancer presence within the peripheral zone was assessed on a per sextant basis by two readers. At 3D MR spectroscopic imaging, cancer was identified by using (choline plus creatine)-to-citrate ratios at cutoff values of 2 and 3 SDs above mean normal peripheral zone values. Data were compared by using receiver operating characteristic analysis. RESULTS: There was no significant difference in the ability of combined MR imaging/3D MR spectroscopic imaging to localize prostate cancer in treated versus control patients. For MR imaging alone, the sensitivity and specificity were 91% and 48% (reader 1) and 75% and 60% (reader 2) in treated patients versus 79% and 60% (reader 1) and 84% and 43% (reader 2) in control patients. For 3D MR spectroscopic imaging alone (>3 SDs cutoff), higher specificity (treated, 80%; controls, 73%) but lower sensitivity (treated, 56%; controls, 53%) was attained. In treated patients, high sensitivity or specificity (up to 92%) was achieved when either or both modalities indicated cancer. CONCLUSION: When performed within 4 months after initiating hormone deprivation therapy, combined MR imaging/3D MR spectroscopic imaging had the same accuracy in localizing prostate cancer as in nontreated patients.

Time-dependent effects of hormone-deprivation therapy on prostate metabolism as detected by combined magnetic resonance imaging and 3D magnetic resonance spectroscopic imaging.

Combined MRI and 3D spectroscopic imaging (MRI/3D-MRSI) was used to study the metabolic effects of hormone-deprivation therapy in 65 prostate cancer patients, who underwent either short, intermediate, or long-term therapy, compared to 30 untreated control patients. There was a significant time-dependent loss of the prostatic metabolites choline, creatine, citrate, and polyamines during hormone-deprivation therapy, resulting in the complete loss of all observable metabolites (total metabolic atrophy) in 25% of patients on long-term therapy. The amount and time-course of metabolite loss during therapy significantly differed for healthy and malignant tissues. Citrate levels decreased faster than choline and creatine levels during therapy, resulting in an increase in the mean (choline + creatine)/citrate ratio with duration of therapy. Due to a loss of all MRSI detectable citrate, this ratio could not be used to identify cancer in 69% of patients on long-term therapy. In the absence of citrate, however, residual prostate cancer could still be detected by elevated choline levels (choline/creatine ratio > or =1.5), or the presence of only choline in the proton spectrum. The loss of citrate and the presence of total metabolic atrophy correlated roughly with decreasing serum prostatic specific antigen levels with increasing therapy. In summary, MRI/3D-MRSI provided both a measure of residual cancer and a time-course of metabolic response following hormone-deprivation therapy. Magn Reson Med 46:49-57, 2001.