G.M. Baxter

Tumour seeding following percutaneous needle biopsy: The real story!

The demand for percutaneous needle biopsy is greater than ever before and with the majority of procedures requiring imaging guidance, radiologists have an increasingly important role in the diagnostic work-up of patients with suspected malignancy. All invasive procedures incur potential risks; therefore, clinicians should be aware of the most frequently encountered complications and have a realistic idea of their likelihood. Tumour seeding, whereby malignant cells are deposited along the tract of a biopsy needle, can have disastrous consequences particularly in patients who are organ transplant candidates or in those who would otherwise expect good long-term survival. Fortunately, tumour seeding is a rare occurrence, yet the issue invariably receives a high profile and is often regarded as a major contraindication to certain biopsy procedures. Although its existence is in no doubt, realistic insight into its likelihood across the spectrum of biopsy procedures and multiple anatomical sites is required to permit accurate patient counselling and risk stratification. This review provides a comprehensive overview of tumour seeding and examines the likelihood of this much feared complication across the range of commonly performed diagnostic biopsy procedures. Conclusions have been derived from an extensive analysis of the published literature, and a number of key recommendations should assist practitioners in their everyday practice.

Colour flow imaging of calf vein thrombosis

Ultrasound and more recently colour Doppler ultrasound has been successfully used in the diagnosis of lower limb venous occlusive disease. Colour Doppler ultrasound has shown promise in the diagnosis of calf vein thrombosis but to date there has been no prospective trial to specifically evaluate its potential. In view of this, we carried out a prospective trial of 50 patients comparing the accuracy of colour Doppler ultrasound with venography in the diagnosis of deep venous thrombosis both above and below knee but in particular with respect to the detection of calf vein clot. Of the 50 patients studied, 10 had only one imaging modality performed as there were eight venographic failures and two ultrasonic failures. Comparison was only thus possible in 40 cases. As in previous studies, colour Doppler ultrasound was shown to be accurate in the diagnosis of thrombosis within the femoro-popliteal veins and had a sensitivity and specificity of 100% respectively. With respect to calf vein lesions, there was one false negative scan using the ultrasonic technique giving a sensitivity of 95%, specificity of 100% and accuracy of 97.5%. We feel colour Doppler ultrasound can and should be used as a first line alternative to venography and can be employed for the exclusion of both above and below knee deep venous thrombosis. Venography should now be reserved for those patients who are unsuitable for ultrasound examination or who have an equivocal ultrasound scan.

Early Measurement of Pulsatility and Resistive Indexes: Correlation with Long-term Renal Transplant Function

PURPOSE To correlate pulsatility index (PI) and resistive index (RI) measured at early specific intervals after transplantation with 1-year estimated glomerular filtration rate (eGFR) and death-censored transplant survival to assess the long-term prognostic value of these Doppler indexes. MATERIALS AND METHODS The local ethics committee was consulted, and no formal approval was required. This retrospective review included 178 consecutive patients (111 male, 67 female; mean age, 43.9 years ± 13.4 [standard deviation]; age range, 16-72 years) undergoing first deceased-donor renal transplantation between 1997 and 2000. All patients were identified from a prospectively maintained database. Spectral Doppler analysis was performed within 1 week after transplantation in all patients and between 1 week and 3 months after transplantation in 124 patients. Average PI and RI were determined from measurements obtained in the upper, lower, and interpolar regions. For statistical analysis, the χ(2) test, analysis of variance, the Student t test, Kaplan-Meier survival plots, and Cox proportional hazards models were used. RESULTS Within 1 week after transplantation, there was a significant association between PI and 1-year eGFR when analyzed as tertiles (P = .02). Between 1 week and 3 months after transplantation, there was a significant relationship between 1-year eGFR and both PI and RI when comparing the lowest and highest tertiles (47.5 mL/min/1.73 m(2) for PI <1.26 vs 32.7 mL/min/1.73 m(2) for PI >1.49 [P = .01], 42.8 mL/min/1.73 m(2) for RI <0.69 vs 32.3 mL/min/1.73 m(2) for RI >0.74 [P = .03]). Both PI and RI were independent predictors of death-censored transplant survival (hazard ratio, 1.68 per unit [P < .001] and 260.4 per unit, respectively [P = .02]). CONCLUSION PI and RI in the early posttransplantation period correlate with long-term transplant function and can potentially be used as prognostic markers to aid risk stratification for future transplant dysfunction.

Extra-renal pseudoaneurysm: An uncommon complication following renal transplantation

Vascular complications are reported in a significant proportion of patients following renal transplantation and are a contributory cause of graft dysfunction. Of these, pseudoaneurysm formation is one of the least common. We present three patients in whom extra-renal transplant artery pseduoaneurysms arising from the surgical anastomosis between the external iliac and renal transplant artery were initially diagnosed with colour Doppler ultrasound, and outline their subsequent management.

Color Doppler Velocunetry of the Optic Nerve Head in Arterial Occlusion

BACKGROUND Color Doppler velocimetry allows simultaneous imaging by B-scan and Doppler ultrasound. This facilitates estimation of blood velocity in the orbital vessels. A pulse arterial waveform providing blood velocity measurements can be obtained from the optic nerve head. The vascular pattern in this region consists of multiple peripapillary blood vessels and a central artery. The exact contribution of the arteries in this area to velocimetry readings was undetermined. METHODS In this study, the arterial pulses at the optic nerve head of seven patients with central retinal artery occlusion (CRAO) and seven with anterior ischemic optic neuropathy (AION) were examined by color Doppler velocimetry. RESULTS No velocimetric measurements were obtainable at the optic nerve head in three of four patients with acute CRAO (examined within 24 hours of onset) despite color recordings obtainable in the peripapillary region. In contrast, all patients with AION showed characteristic arterial pulse waveforms from the artery that was situated centrally in the optic nerve. No peripapillary color indices were detectable in three of the four patients with ischemic optic neuropathy who were examined within 24 hours of onset of their symptoms. Follow-up investigation showed that there was reperfusion of both arterial circulations within 1 week. CONCLUSION The results demonstrate that color Doppler ultrasound of the optic nerve head provides velocimetric measurements of blood flow in the central retinal artery. Although some investigators using different apparatuses have produced velocimetry measurements from the posterior ciliary arteries, in this study reliable measurements were not obtainable form color indices in the peripapillary area.

Colour Doppler velocimetry of the arterial vasculature of the optic nerve head and orbit

Blood flow in the orbital vasculature can be investigated by colour Doppler velocimetry which allows simultaneous imaging of B-scan and Doppler ultrasound. In this paper we review the results of our recent studies on the arterial vasculature of the orbit and optic nerve head. A control study is described in which reliable measurements were obtained from the ophthalmic artery at the orbital apex, the medial orbit, and the complex of the central retinal artery and posterior ciliary arteries. Patients with occlusion of the central retinal artery and posterior ciliary arteries were examined. The results indicate that readings at the optic nerve head primarily represent blood flow in the central retinal artery. A study of the effects of posture on velocimetry demonstrated no change in the measurements obtained. Finally, topical timolol 0.5% was found to reduce the resistive indices of flow in the central retinal artery.

Ultrasonic microbubble contrast agents and the transplant kidney

AIM To evaluate the potential application of microbubble agents in the immediate post-transplant period, by studying contrast uptake and washout, and to correlate these values with clinical indices, and thus, assess the potential prognostic value of this technique. MATERIALS AND METHODS The study group comprised 20 consecutive renal transplant patients within 7 days of transplantation. Sonovue was administered as an intravenous bolus with continuous imaging of the transplant kidney at low mechanical index (MI) for 1 min post-injection. These data were analysed off-line by two observers, and time intensity curves (TIC) for the upper, mid, and lower poles constructed. Within each pole, a region of interest (5 mm square) was placed over the cortex, medullary pyramid, and interlobar artery, resulting in a total of nine TIC for each patient. TIC parameters included the arrival time (AT), time to peak (TTP), peak intensity (Max), gradient of the slope (M), and the area under curve (AUC). RESULTS For both observers there was good agreement for all values measured from the cortex and medulla, but poor interobserver correlation for the vascular values. In addition, there was only agreement for these values in the upper and mid-pole of the transplant with poor agreement for the lower pole values. The mid-pole of the transplant kidney was chosen as the point of measurement for subsequent studies. Mid-pole values were correlated with clinical data and outcome over the 3-month post-transplant period. Renal microbubble perfusion correlated with the transplant estimated glomerular filtration rate (eGFR) at 3 months post-transplantation (p=0.016). DISCUSSION In conclusion, this is the first study to confirm reproducibility of the Sonovue TIC data in transplant patients and to quantify regional variation and perfusion. The statistically significant estimates of transplant perfusion may be of future benefit to transplant recipients and potentially utilized as a prognostic tool. However, a more in depth study will be required to support or refute these early study findings.

Long-term outcome of transplant renal artery stenosis managed conservatively or by radiological intervention.

Abstract:  The natural history and optimal treatment of transplant renal artery stenosis (TRAS) is poorly defined. Few studies reported long‐term clinical outcomes. A single centre analysis of 43 patients diagnosed with TRAS 1990–2003 was performed. Twenty‐seven had percutaneous intervention (including 10 patients who had >1 intervention) and 16 were managed conservatively at the discretion of the attending clinicians. Transplant function was assessed by slope of estimated glomerular filtration rate (eGFR) over five yr of follow‐up. Patients in the intervention group had lower mean eGFR (36.3 mL/min/1.73 m2 vs. 46.3 mL/min/1.73 m2; p = 0.07) at baseline. Five transplants in the intervention group failed (including two as a direct result of intervention) and one in the conservative group failed. There was no significant difference in the rate of deterioration in renal function (mean slope of eGFR minus 0.8 mL/min/yr and minus 1.0 mL/min/yr in the intervention and conservative groups, respectively; p = 0.79). There was no significant difference in blood pressure or number of anti‐hypertensive agents between the groups at any time point. Baseline Doppler ultrasound indices showed no significant correlation with slope of eGFR in either group. Our data demonstrate that selected patients with TRAS can be managed without intervention and that this approach is associated with good long‐term outcome. Selection of appropriate patients for intervention remains difficult and larger randomized studies are required.

The Value of Serial Doppler Imaging in Central Retinal Vein Occlusion: Correlation With Visual Recovery

A prospective study of 80 patients with central retinal vein occlusion (CRVO) was performed to determine whether Doppler flow measurements can predict visual outcome. All patients at presentation, had full ophthalmological examination, fluorescein angiography, relative afferent pupillary defect test and electroretinography to distinguish between ischaemic and non-ischaemic occlusions. In addition, all patients were examined at presentation with colour Doppler ultrasound using a 7.5 MHz linear array probe. Both the clinical examinations and colour Doppler ultrasound were repeated at one year following initial presentation in a smaller group of 20 patients. A significant reduction in velocity within the central retinal vein was noted in the ischaemic compared with non-ischaemic CRVO affected eye at the time of the baseline scan. The minimum venous velocity within the central retinal vein was most severely affected. No velocity difference was present within the ophthalmic artery. Follow-up at one year with colour Doppler ultrasound showed an increase in blood velocity values within the central retinal vein in the CRVO affected eye but this was of no prognostic value and did not correlate with clinical outcome. Serial colour Doppler ultrasound examinations, therefore, have no clinical application in patients with CRVO and are of no prognostic value.

Renal transplant vein occlusion: An early diagnostic sign?

We report new Doppler ultrasound findings in two patients with renal vein thrombosis and obstruction following renal transplantation. In both cases there was a marked reduction in the systolic peak with relatively normal diastolic flow in the intrarenal arterial waveforms. Venous flow was still detectable at the renal hilum in both cases, and throughout the graft in one case. We suggest that, in the absence of signs of proximal renal artery stenosis, small amplitude arterial waveforms with a depressed systolic peak and maintained diastolic flow, despite intrarenal venous flow, represent renal vein thrombosis in evolution or renal vein obstruction. These findings merit early surgical exploration.